diff --git a/Android.bp b/Android.bp
new file mode 100644
index 0000000..16adbfb
--- /dev/null
+++ b/Android.bp
@@ -0,0 +1,22 @@
+// Copyright 2017 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+python_library {
+  name: "py2-futures",
+  srcs: [
+    "concurrent/**/*.py",
+  ],
+  defaults: ["py2_only"],
+}
+
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..a8d65b1
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,48 @@
+PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2
+--------------------------------------------
+
+1. This LICENSE AGREEMENT is between the Python Software Foundation
+("PSF"), and the Individual or Organization ("Licensee") accessing and
+otherwise using this software ("Python") in source or binary form and
+its associated documentation.
+
+2. Subject to the terms and conditions of this License Agreement, PSF
+hereby grants Licensee a nonexclusive, royalty-free, world-wide
+license to reproduce, analyze, test, perform and/or display publicly,
+prepare derivative works, distribute, and otherwise use Python
+alone or in any derivative version, provided, however, that PSF's
+License Agreement and PSF's notice of copyright, i.e., "Copyright (c)
+2001, 2002, 2003, 2004, 2005, 2006 Python Software Foundation; All Rights
+Reserved" are retained in Python alone or in any derivative version 
+prepared by Licensee.
+
+3. In the event Licensee prepares a derivative work that is based on
+or incorporates Python or any part thereof, and wants to make
+the derivative work available to others as provided herein, then
+Licensee hereby agrees to include in any such work a brief summary of
+the changes made to Python.
+
+4. PSF is making Python available to Licensee on an "AS IS"
+basis.  PSF MAKES NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR
+IMPLIED.  BY WAY OF EXAMPLE, BUT NOT LIMITATION, PSF MAKES NO AND
+DISCLAIMS ANY REPRESENTATION OR WARRANTY OF MERCHANTABILITY OR FITNESS
+FOR ANY PARTICULAR PURPOSE OR THAT THE USE OF PYTHON WILL NOT
+INFRINGE ANY THIRD PARTY RIGHTS.
+
+5. PSF SHALL NOT BE LIABLE TO LICENSEE OR ANY OTHER USERS OF PYTHON
+FOR ANY INCIDENTAL, SPECIAL, OR CONSEQUENTIAL DAMAGES OR LOSS AS
+A RESULT OF MODIFYING, DISTRIBUTING, OR OTHERWISE USING PYTHON,
+OR ANY DERIVATIVE THEREOF, EVEN IF ADVISED OF THE POSSIBILITY THEREOF.
+
+6. This License Agreement will automatically terminate upon a material
+breach of its terms and conditions.
+
+7. Nothing in this License Agreement shall be deemed to create any
+relationship of agency, partnership, or joint venture between PSF and
+Licensee.  This License Agreement does not grant permission to use PSF
+trademarks or trade name in a trademark sense to endorse or promote
+products or services of Licensee, or any third party.
+
+8. By copying, installing or otherwise using Python, Licensee
+agrees to be bound by the terms and conditions of this License
+Agreement.
diff --git a/MANIFEST.in b/MANIFEST.in
new file mode 100644
index 0000000..52860d0
--- /dev/null
+++ b/MANIFEST.in
@@ -0,0 +1,5 @@
+recursive-include docs *
+include *.py
+include tox.ini
+include CHANGES
+include LICENSE
diff --git a/METADATA b/METADATA
new file mode 100644
index 0000000..2ed3777
--- /dev/null
+++ b/METADATA
@@ -0,0 +1,16 @@
+name: "futures"
+description:
+    "Python PyPI futures package"
+
+third_party {
+  url {
+    type: HOMEPAGE
+    value: "https://pypi.python.org/pypi/futures/3.2.0"
+  }
+  url {
+    type: GIT
+    value: "https://github.com/agronholm/pythonfutures"
+  }
+  version: "3.2.0"
+  last_upgrade_date { year: 2018 month: 1 day: 4 }
+}
diff --git a/MODULE_LICENSE_APACHE2 b/MODULE_LICENSE_APACHE2
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/MODULE_LICENSE_APACHE2
diff --git a/NOTICE b/NOTICE
new file mode 100644
index 0000000..a8d65b1
--- /dev/null
+++ b/NOTICE
@@ -0,0 +1,48 @@
+PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2
+--------------------------------------------
+
+1. This LICENSE AGREEMENT is between the Python Software Foundation
+("PSF"), and the Individual or Organization ("Licensee") accessing and
+otherwise using this software ("Python") in source or binary form and
+its associated documentation.
+
+2. Subject to the terms and conditions of this License Agreement, PSF
+hereby grants Licensee a nonexclusive, royalty-free, world-wide
+license to reproduce, analyze, test, perform and/or display publicly,
+prepare derivative works, distribute, and otherwise use Python
+alone or in any derivative version, provided, however, that PSF's
+License Agreement and PSF's notice of copyright, i.e., "Copyright (c)
+2001, 2002, 2003, 2004, 2005, 2006 Python Software Foundation; All Rights
+Reserved" are retained in Python alone or in any derivative version 
+prepared by Licensee.
+
+3. In the event Licensee prepares a derivative work that is based on
+or incorporates Python or any part thereof, and wants to make
+the derivative work available to others as provided herein, then
+Licensee hereby agrees to include in any such work a brief summary of
+the changes made to Python.
+
+4. PSF is making Python available to Licensee on an "AS IS"
+basis.  PSF MAKES NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR
+IMPLIED.  BY WAY OF EXAMPLE, BUT NOT LIMITATION, PSF MAKES NO AND
+DISCLAIMS ANY REPRESENTATION OR WARRANTY OF MERCHANTABILITY OR FITNESS
+FOR ANY PARTICULAR PURPOSE OR THAT THE USE OF PYTHON WILL NOT
+INFRINGE ANY THIRD PARTY RIGHTS.
+
+5. PSF SHALL NOT BE LIABLE TO LICENSEE OR ANY OTHER USERS OF PYTHON
+FOR ANY INCIDENTAL, SPECIAL, OR CONSEQUENTIAL DAMAGES OR LOSS AS
+A RESULT OF MODIFYING, DISTRIBUTING, OR OTHERWISE USING PYTHON,
+OR ANY DERIVATIVE THEREOF, EVEN IF ADVISED OF THE POSSIBILITY THEREOF.
+
+6. This License Agreement will automatically terminate upon a material
+breach of its terms and conditions.
+
+7. Nothing in this License Agreement shall be deemed to create any
+relationship of agency, partnership, or joint venture between PSF and
+Licensee.  This License Agreement does not grant permission to use PSF
+trademarks or trade name in a trademark sense to endorse or promote
+products or services of Licensee, or any third party.
+
+8. By copying, installing or otherwise using Python, Licensee
+agrees to be bound by the terms and conditions of this License
+Agreement.
diff --git a/PKG-INFO b/PKG-INFO
new file mode 100644
index 0000000..e03caec
--- /dev/null
+++ b/PKG-INFO
@@ -0,0 +1,52 @@
+Metadata-Version: 1.2
+Name: futures
+Version: 3.2.0
+Summary: Backport of the concurrent.futures package from Python 3
+Home-page: https://github.com/agronholm/pythonfutures
+Author: Alex Grönholm
+Author-email: alex.gronholm@nextday.fi
+License: PSF
+Description: .. image:: https://travis-ci.org/agronholm/pythonfutures.svg?branch=master
+          :target: https://travis-ci.org/agronholm/pythonfutures
+          :alt: Build Status
+        
+        This is a backport of the `concurrent.futures`_ standard library module to Python 2.
+        
+        It should not be installed on Python 3, although there should be no harm in doing so, as the
+        standard library takes precedence over third party libraries.
+        
+        To conditionally require this library only on Python 2, you can do this in your ``setup.py``:
+        
+        .. code-block:: python
+        
+            setup(
+                ...
+                extras_require={
+                    ':python_version == "2.7"': ['futures']
+                }
+            )
+        
+        Or, using the newer syntax:
+        
+        .. code-block:: python
+        
+            setup(
+                ...
+                install_requires={
+                    'futures; python_version == "2.7"'
+                }
+            )
+        
+        .. warning:: The ``ProcessPoolExecutor`` class has known (unfixable) problems on Python 2 and
+          should not be relied on for mission critical work.
+        
+        .. _concurrent.futures: https://docs.python.org/library/concurrent.futures.html
+        
+Platform: UNKNOWN
+Classifier: License :: OSI Approved :: Python Software Foundation License
+Classifier: Development Status :: 5 - Production/Stable
+Classifier: Intended Audience :: Developers
+Classifier: Programming Language :: Python :: 2.6
+Classifier: Programming Language :: Python :: 2.7
+Classifier: Programming Language :: Python :: 2 :: Only
+Requires-Python: >=2.6, <3
diff --git a/README.rst b/README.rst
new file mode 100644
index 0000000..1f072e4
--- /dev/null
+++ b/README.rst
@@ -0,0 +1,35 @@
+.. image:: https://travis-ci.org/agronholm/pythonfutures.svg?branch=master
+  :target: https://travis-ci.org/agronholm/pythonfutures
+  :alt: Build Status
+
+This is a backport of the `concurrent.futures`_ standard library module to Python 2.
+
+It should not be installed on Python 3, although there should be no harm in doing so, as the
+standard library takes precedence over third party libraries.
+
+To conditionally require this library only on Python 2, you can do this in your ``setup.py``:
+
+.. code-block:: python
+
+    setup(
+        ...
+        extras_require={
+            ':python_version == "2.7"': ['futures']
+        }
+    )
+
+Or, using the newer syntax:
+
+.. code-block:: python
+
+    setup(
+        ...
+        install_requires={
+            'futures; python_version == "2.7"'
+        }
+    )
+
+.. warning:: The ``ProcessPoolExecutor`` class has known (unfixable) problems on Python 2 and
+  should not be relied on for mission critical work.
+
+.. _concurrent.futures: https://docs.python.org/library/concurrent.futures.html
diff --git a/concurrent/__init__.py b/concurrent/__init__.py
new file mode 100644
index 0000000..b36383a
--- /dev/null
+++ b/concurrent/__init__.py
@@ -0,0 +1,3 @@
+from pkgutil import extend_path
+
+__path__ = extend_path(__path__, __name__)
diff --git a/concurrent/futures/__init__.py b/concurrent/futures/__init__.py
new file mode 100644
index 0000000..428b14b
--- /dev/null
+++ b/concurrent/futures/__init__.py
@@ -0,0 +1,23 @@
+# Copyright 2009 Brian Quinlan. All Rights Reserved.
+# Licensed to PSF under a Contributor Agreement.
+
+"""Execute computations asynchronously using threads or processes."""
+
+__author__ = 'Brian Quinlan (brian@sweetapp.com)'
+
+from concurrent.futures._base import (FIRST_COMPLETED,
+                                      FIRST_EXCEPTION,
+                                      ALL_COMPLETED,
+                                      CancelledError,
+                                      TimeoutError,
+                                      Future,
+                                      Executor,
+                                      wait,
+                                      as_completed)
+from concurrent.futures.thread import ThreadPoolExecutor
+
+try:
+    from concurrent.futures.process import ProcessPoolExecutor
+except ImportError:
+    # some platforms don't have multiprocessing
+    pass
diff --git a/concurrent/futures/_base.py b/concurrent/futures/_base.py
new file mode 100644
index 0000000..510ffa5
--- /dev/null
+++ b/concurrent/futures/_base.py
@@ -0,0 +1,667 @@
+# Copyright 2009 Brian Quinlan. All Rights Reserved.
+# Licensed to PSF under a Contributor Agreement.
+
+import collections
+import logging
+import threading
+import itertools
+import time
+import types
+
+__author__ = 'Brian Quinlan (brian@sweetapp.com)'
+
+FIRST_COMPLETED = 'FIRST_COMPLETED'
+FIRST_EXCEPTION = 'FIRST_EXCEPTION'
+ALL_COMPLETED = 'ALL_COMPLETED'
+_AS_COMPLETED = '_AS_COMPLETED'
+
+# Possible future states (for internal use by the futures package).
+PENDING = 'PENDING'
+RUNNING = 'RUNNING'
+# The future was cancelled by the user...
+CANCELLED = 'CANCELLED'
+# ...and _Waiter.add_cancelled() was called by a worker.
+CANCELLED_AND_NOTIFIED = 'CANCELLED_AND_NOTIFIED'
+FINISHED = 'FINISHED'
+
+_FUTURE_STATES = [
+    PENDING,
+    RUNNING,
+    CANCELLED,
+    CANCELLED_AND_NOTIFIED,
+    FINISHED
+]
+
+_STATE_TO_DESCRIPTION_MAP = {
+    PENDING: "pending",
+    RUNNING: "running",
+    CANCELLED: "cancelled",
+    CANCELLED_AND_NOTIFIED: "cancelled",
+    FINISHED: "finished"
+}
+
+# Logger for internal use by the futures package.
+LOGGER = logging.getLogger("concurrent.futures")
+
+class Error(Exception):
+    """Base class for all future-related exceptions."""
+    pass
+
+class CancelledError(Error):
+    """The Future was cancelled."""
+    pass
+
+class TimeoutError(Error):
+    """The operation exceeded the given deadline."""
+    pass
+
+class _Waiter(object):
+    """Provides the event that wait() and as_completed() block on."""
+    def __init__(self):
+        self.event = threading.Event()
+        self.finished_futures = []
+
+    def add_result(self, future):
+        self.finished_futures.append(future)
+
+    def add_exception(self, future):
+        self.finished_futures.append(future)
+
+    def add_cancelled(self, future):
+        self.finished_futures.append(future)
+
+class _AsCompletedWaiter(_Waiter):
+    """Used by as_completed()."""
+
+    def __init__(self):
+        super(_AsCompletedWaiter, self).__init__()
+        self.lock = threading.Lock()
+
+    def add_result(self, future):
+        with self.lock:
+            super(_AsCompletedWaiter, self).add_result(future)
+            self.event.set()
+
+    def add_exception(self, future):
+        with self.lock:
+            super(_AsCompletedWaiter, self).add_exception(future)
+            self.event.set()
+
+    def add_cancelled(self, future):
+        with self.lock:
+            super(_AsCompletedWaiter, self).add_cancelled(future)
+            self.event.set()
+
+class _FirstCompletedWaiter(_Waiter):
+    """Used by wait(return_when=FIRST_COMPLETED)."""
+
+    def add_result(self, future):
+        super(_FirstCompletedWaiter, self).add_result(future)
+        self.event.set()
+
+    def add_exception(self, future):
+        super(_FirstCompletedWaiter, self).add_exception(future)
+        self.event.set()
+
+    def add_cancelled(self, future):
+        super(_FirstCompletedWaiter, self).add_cancelled(future)
+        self.event.set()
+
+class _AllCompletedWaiter(_Waiter):
+    """Used by wait(return_when=FIRST_EXCEPTION and ALL_COMPLETED)."""
+
+    def __init__(self, num_pending_calls, stop_on_exception):
+        self.num_pending_calls = num_pending_calls
+        self.stop_on_exception = stop_on_exception
+        self.lock = threading.Lock()
+        super(_AllCompletedWaiter, self).__init__()
+
+    def _decrement_pending_calls(self):
+        with self.lock:
+            self.num_pending_calls -= 1
+            if not self.num_pending_calls:
+                self.event.set()
+
+    def add_result(self, future):
+        super(_AllCompletedWaiter, self).add_result(future)
+        self._decrement_pending_calls()
+
+    def add_exception(self, future):
+        super(_AllCompletedWaiter, self).add_exception(future)
+        if self.stop_on_exception:
+            self.event.set()
+        else:
+            self._decrement_pending_calls()
+
+    def add_cancelled(self, future):
+        super(_AllCompletedWaiter, self).add_cancelled(future)
+        self._decrement_pending_calls()
+
+class _AcquireFutures(object):
+    """A context manager that does an ordered acquire of Future conditions."""
+
+    def __init__(self, futures):
+        self.futures = sorted(futures, key=id)
+
+    def __enter__(self):
+        for future in self.futures:
+            future._condition.acquire()
+
+    def __exit__(self, *args):
+        for future in self.futures:
+            future._condition.release()
+
+def _create_and_install_waiters(fs, return_when):
+    if return_when == _AS_COMPLETED:
+        waiter = _AsCompletedWaiter()
+    elif return_when == FIRST_COMPLETED:
+        waiter = _FirstCompletedWaiter()
+    else:
+        pending_count = sum(
+                f._state not in [CANCELLED_AND_NOTIFIED, FINISHED] for f in fs)
+
+        if return_when == FIRST_EXCEPTION:
+            waiter = _AllCompletedWaiter(pending_count, stop_on_exception=True)
+        elif return_when == ALL_COMPLETED:
+            waiter = _AllCompletedWaiter(pending_count, stop_on_exception=False)
+        else:
+            raise ValueError("Invalid return condition: %r" % return_when)
+
+    for f in fs:
+        f._waiters.append(waiter)
+
+    return waiter
+
+
+def _yield_finished_futures(fs, waiter, ref_collect):
+    """
+    Iterate on the list *fs*, yielding finished futures one by one in
+    reverse order.
+    Before yielding a future, *waiter* is removed from its waiters
+    and the future is removed from each set in the collection of sets
+    *ref_collect*.
+
+    The aim of this function is to avoid keeping stale references after
+    the future is yielded and before the iterator resumes.
+    """
+    while fs:
+        f = fs[-1]
+        for futures_set in ref_collect:
+            futures_set.remove(f)
+        with f._condition:
+            f._waiters.remove(waiter)
+        del f
+        # Careful not to keep a reference to the popped value
+        yield fs.pop()
+
+
+def as_completed(fs, timeout=None):
+    """An iterator over the given futures that yields each as it completes.
+
+    Args:
+        fs: The sequence of Futures (possibly created by different Executors) to
+            iterate over.
+        timeout: The maximum number of seconds to wait. If None, then there
+            is no limit on the wait time.
+
+    Returns:
+        An iterator that yields the given Futures as they complete (finished or
+        cancelled). If any given Futures are duplicated, they will be returned
+        once.
+
+    Raises:
+        TimeoutError: If the entire result iterator could not be generated
+            before the given timeout.
+    """
+    if timeout is not None:
+        end_time = timeout + time.time()
+
+    fs = set(fs)
+    total_futures = len(fs)
+    with _AcquireFutures(fs):
+        finished = set(
+                f for f in fs
+                if f._state in [CANCELLED_AND_NOTIFIED, FINISHED])
+        pending = fs - finished
+        waiter = _create_and_install_waiters(fs, _AS_COMPLETED)
+    finished = list(finished)
+    try:
+        for f in _yield_finished_futures(finished, waiter,
+                                         ref_collect=(fs,)):
+            f = [f]
+            yield f.pop()
+
+        while pending:
+            if timeout is None:
+                wait_timeout = None
+            else:
+                wait_timeout = end_time - time.time()
+                if wait_timeout < 0:
+                    raise TimeoutError(
+                            '%d (of %d) futures unfinished' % (
+                            len(pending), total_futures))
+
+            waiter.event.wait(wait_timeout)
+
+            with waiter.lock:
+                finished = waiter.finished_futures
+                waiter.finished_futures = []
+                waiter.event.clear()
+
+            # reverse to keep finishing order
+            finished.reverse()
+            for f in _yield_finished_futures(finished, waiter,
+                                             ref_collect=(fs, pending)):
+                f = [f]
+                yield f.pop()
+
+    finally:
+        # Remove waiter from unfinished futures
+        for f in fs:
+            with f._condition:
+                f._waiters.remove(waiter)
+
+DoneAndNotDoneFutures = collections.namedtuple(
+        'DoneAndNotDoneFutures', 'done not_done')
+def wait(fs, timeout=None, return_when=ALL_COMPLETED):
+    """Wait for the futures in the given sequence to complete.
+
+    Args:
+        fs: The sequence of Futures (possibly created by different Executors) to
+            wait upon.
+        timeout: The maximum number of seconds to wait. If None, then there
+            is no limit on the wait time.
+        return_when: Indicates when this function should return. The options
+            are:
+
+            FIRST_COMPLETED - Return when any future finishes or is
+                              cancelled.
+            FIRST_EXCEPTION - Return when any future finishes by raising an
+                              exception. If no future raises an exception
+                              then it is equivalent to ALL_COMPLETED.
+            ALL_COMPLETED -   Return when all futures finish or are cancelled.
+
+    Returns:
+        A named 2-tuple of sets. The first set, named 'done', contains the
+        futures that completed (is finished or cancelled) before the wait
+        completed. The second set, named 'not_done', contains uncompleted
+        futures.
+    """
+    with _AcquireFutures(fs):
+        done = set(f for f in fs
+                   if f._state in [CANCELLED_AND_NOTIFIED, FINISHED])
+        not_done = set(fs) - done
+
+        if (return_when == FIRST_COMPLETED) and done:
+            return DoneAndNotDoneFutures(done, not_done)
+        elif (return_when == FIRST_EXCEPTION) and done:
+            if any(f for f in done
+                   if not f.cancelled() and f.exception() is not None):
+                return DoneAndNotDoneFutures(done, not_done)
+
+        if len(done) == len(fs):
+            return DoneAndNotDoneFutures(done, not_done)
+
+        waiter = _create_and_install_waiters(fs, return_when)
+
+    waiter.event.wait(timeout)
+    for f in fs:
+        with f._condition:
+            f._waiters.remove(waiter)
+
+    done.update(waiter.finished_futures)
+    return DoneAndNotDoneFutures(done, set(fs) - done)
+
+class Future(object):
+    """Represents the result of an asynchronous computation."""
+
+    def __init__(self):
+        """Initializes the future. Should not be called by clients."""
+        self._condition = threading.Condition()
+        self._state = PENDING
+        self._result = None
+        self._exception = None
+        self._traceback = None
+        self._waiters = []
+        self._done_callbacks = []
+
+    def _invoke_callbacks(self):
+        for callback in self._done_callbacks:
+            try:
+                callback(self)
+            except Exception:
+                LOGGER.exception('exception calling callback for %r', self)
+            except BaseException:
+                # Explicitly let all other new-style exceptions through so
+                # that we can catch all old-style exceptions with a simple
+                # "except:" clause below.
+                #
+                # All old-style exception objects are instances of
+                # types.InstanceType, but "except types.InstanceType:" does
+                # not catch old-style exceptions for some reason.  Thus, the
+                # only way to catch all old-style exceptions without catching
+                # any new-style exceptions is to filter out the new-style
+                # exceptions, which all derive from BaseException.
+                raise
+            except:
+                # Because of the BaseException clause above, this handler only
+                # executes for old-style exception objects.
+                LOGGER.exception('exception calling callback for %r', self)
+
+    def __repr__(self):
+        with self._condition:
+            if self._state == FINISHED:
+                if self._exception:
+                    return '<%s at %#x state=%s raised %s>' % (
+                        self.__class__.__name__,
+                        id(self),
+                        _STATE_TO_DESCRIPTION_MAP[self._state],
+                        self._exception.__class__.__name__)
+                else:
+                    return '<%s at %#x state=%s returned %s>' % (
+                        self.__class__.__name__,
+                        id(self),
+                        _STATE_TO_DESCRIPTION_MAP[self._state],
+                        self._result.__class__.__name__)
+            return '<%s at %#x state=%s>' % (
+                    self.__class__.__name__,
+                    id(self),
+                   _STATE_TO_DESCRIPTION_MAP[self._state])
+
+    def cancel(self):
+        """Cancel the future if possible.
+
+        Returns True if the future was cancelled, False otherwise. A future
+        cannot be cancelled if it is running or has already completed.
+        """
+        with self._condition:
+            if self._state in [RUNNING, FINISHED]:
+                return False
+
+            if self._state in [CANCELLED, CANCELLED_AND_NOTIFIED]:
+                return True
+
+            self._state = CANCELLED
+            self._condition.notify_all()
+
+        self._invoke_callbacks()
+        return True
+
+    def cancelled(self):
+        """Return True if the future was cancelled."""
+        with self._condition:
+            return self._state in [CANCELLED, CANCELLED_AND_NOTIFIED]
+
+    def running(self):
+        """Return True if the future is currently executing."""
+        with self._condition:
+            return self._state == RUNNING
+
+    def done(self):
+        """Return True of the future was cancelled or finished executing."""
+        with self._condition:
+            return self._state in [CANCELLED, CANCELLED_AND_NOTIFIED, FINISHED]
+
+    def __get_result(self):
+        if self._exception:
+            if isinstance(self._exception, types.InstanceType):
+                # The exception is an instance of an old-style class, which
+                # means type(self._exception) returns types.ClassType instead
+                # of the exception's actual class type.
+                exception_type = self._exception.__class__
+            else:
+                exception_type = type(self._exception)
+            raise exception_type, self._exception, self._traceback
+        else:
+            return self._result
+
+    def add_done_callback(self, fn):
+        """Attaches a callable that will be called when the future finishes.
+
+        Args:
+            fn: A callable that will be called with this future as its only
+                argument when the future completes or is cancelled. The callable
+                will always be called by a thread in the same process in which
+                it was added. If the future has already completed or been
+                cancelled then the callable will be called immediately. These
+                callables are called in the order that they were added.
+        """
+        with self._condition:
+            if self._state not in [CANCELLED, CANCELLED_AND_NOTIFIED, FINISHED]:
+                self._done_callbacks.append(fn)
+                return
+        fn(self)
+
+    def result(self, timeout=None):
+        """Return the result of the call that the future represents.
+
+        Args:
+            timeout: The number of seconds to wait for the result if the future
+                isn't done. If None, then there is no limit on the wait time.
+
+        Returns:
+            The result of the call that the future represents.
+
+        Raises:
+            CancelledError: If the future was cancelled.
+            TimeoutError: If the future didn't finish executing before the given
+                timeout.
+            Exception: If the call raised then that exception will be raised.
+        """
+        with self._condition:
+            if self._state in [CANCELLED, CANCELLED_AND_NOTIFIED]:
+                raise CancelledError()
+            elif self._state == FINISHED:
+                return self.__get_result()
+
+            self._condition.wait(timeout)
+
+            if self._state in [CANCELLED, CANCELLED_AND_NOTIFIED]:
+                raise CancelledError()
+            elif self._state == FINISHED:
+                return self.__get_result()
+            else:
+                raise TimeoutError()
+
+    def exception_info(self, timeout=None):
+        """Return a tuple of (exception, traceback) raised by the call that the
+        future represents.
+
+        Args:
+            timeout: The number of seconds to wait for the exception if the
+                future isn't done. If None, then there is no limit on the wait
+                time.
+
+        Returns:
+            The exception raised by the call that the future represents or None
+            if the call completed without raising.
+
+        Raises:
+            CancelledError: If the future was cancelled.
+            TimeoutError: If the future didn't finish executing before the given
+                timeout.
+        """
+        with self._condition:
+            if self._state in [CANCELLED, CANCELLED_AND_NOTIFIED]:
+                raise CancelledError()
+            elif self._state == FINISHED:
+                return self._exception, self._traceback
+
+            self._condition.wait(timeout)
+
+            if self._state in [CANCELLED, CANCELLED_AND_NOTIFIED]:
+                raise CancelledError()
+            elif self._state == FINISHED:
+                return self._exception, self._traceback
+            else:
+                raise TimeoutError()
+
+    def exception(self, timeout=None):
+        """Return the exception raised by the call that the future represents.
+
+        Args:
+            timeout: The number of seconds to wait for the exception if the
+                future isn't done. If None, then there is no limit on the wait
+                time.
+
+        Returns:
+            The exception raised by the call that the future represents or None
+            if the call completed without raising.
+
+        Raises:
+            CancelledError: If the future was cancelled.
+            TimeoutError: If the future didn't finish executing before the given
+                timeout.
+        """
+        return self.exception_info(timeout)[0]
+
+    # The following methods should only be used by Executors and in tests.
+    def set_running_or_notify_cancel(self):
+        """Mark the future as running or process any cancel notifications.
+
+        Should only be used by Executor implementations and unit tests.
+
+        If the future has been cancelled (cancel() was called and returned
+        True) then any threads waiting on the future completing (though calls
+        to as_completed() or wait()) are notified and False is returned.
+
+        If the future was not cancelled then it is put in the running state
+        (future calls to running() will return True) and True is returned.
+
+        This method should be called by Executor implementations before
+        executing the work associated with this future. If this method returns
+        False then the work should not be executed.
+
+        Returns:
+            False if the Future was cancelled, True otherwise.
+
+        Raises:
+            RuntimeError: if this method was already called or if set_result()
+                or set_exception() was called.
+        """
+        with self._condition:
+            if self._state == CANCELLED:
+                self._state = CANCELLED_AND_NOTIFIED
+                for waiter in self._waiters:
+                    waiter.add_cancelled(self)
+                # self._condition.notify_all() is not necessary because
+                # self.cancel() triggers a notification.
+                return False
+            elif self._state == PENDING:
+                self._state = RUNNING
+                return True
+            else:
+                LOGGER.critical('Future %s in unexpected state: %s',
+                                id(self),
+                                self._state)
+                raise RuntimeError('Future in unexpected state')
+
+    def set_result(self, result):
+        """Sets the return value of work associated with the future.
+
+        Should only be used by Executor implementations and unit tests.
+        """
+        with self._condition:
+            self._result = result
+            self._state = FINISHED
+            for waiter in self._waiters:
+                waiter.add_result(self)
+            self._condition.notify_all()
+        self._invoke_callbacks()
+
+    def set_exception_info(self, exception, traceback):
+        """Sets the result of the future as being the given exception
+        and traceback.
+
+        Should only be used by Executor implementations and unit tests.
+        """
+        with self._condition:
+            self._exception = exception
+            self._traceback = traceback
+            self._state = FINISHED
+            for waiter in self._waiters:
+                waiter.add_exception(self)
+            self._condition.notify_all()
+        self._invoke_callbacks()
+
+    def set_exception(self, exception):
+        """Sets the result of the future as being the given exception.
+
+        Should only be used by Executor implementations and unit tests.
+        """
+        self.set_exception_info(exception, None)
+
+class Executor(object):
+    """This is an abstract base class for concrete asynchronous executors."""
+
+    def submit(self, fn, *args, **kwargs):
+        """Submits a callable to be executed with the given arguments.
+
+        Schedules the callable to be executed as fn(*args, **kwargs) and returns
+        a Future instance representing the execution of the callable.
+
+        Returns:
+            A Future representing the given call.
+        """
+        raise NotImplementedError()
+
+    def map(self, fn, *iterables, **kwargs):
+        """Returns an iterator equivalent to map(fn, iter).
+
+        Args:
+            fn: A callable that will take as many arguments as there are
+                passed iterables.
+            timeout: The maximum number of seconds to wait. If None, then there
+                is no limit on the wait time.
+
+        Returns:
+            An iterator equivalent to: map(func, *iterables) but the calls may
+            be evaluated out-of-order.
+
+        Raises:
+            TimeoutError: If the entire result iterator could not be generated
+                before the given timeout.
+            Exception: If fn(*args) raises for any values.
+        """
+        timeout = kwargs.get('timeout')
+        if timeout is not None:
+            end_time = timeout + time.time()
+
+        fs = [self.submit(fn, *args) for args in itertools.izip(*iterables)]
+
+        # Yield must be hidden in closure so that the futures are submitted
+        # before the first iterator value is required.
+        def result_iterator():
+            try:
+                # reverse to keep finishing order
+                fs.reverse()
+                while fs:
+                    # Careful not to keep a reference to the popped future
+                    if timeout is None:
+                        yield fs.pop().result()
+                    else:
+                        yield fs.pop().result(end_time - time.time())
+            finally:
+                for future in fs:
+                    future.cancel()
+        return result_iterator()
+
+    def shutdown(self, wait=True):
+        """Clean-up the resources associated with the Executor.
+
+        It is safe to call this method several times. Otherwise, no other
+        methods can be called after this one.
+
+        Args:
+            wait: If True then shutdown will not return until all running
+                futures have finished executing and the resources used by the
+                executor have been reclaimed.
+        """
+        pass
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.shutdown(wait=True)
+        return False
diff --git a/concurrent/futures/process.py b/concurrent/futures/process.py
new file mode 100644
index 0000000..fa5b96f
--- /dev/null
+++ b/concurrent/futures/process.py
@@ -0,0 +1,363 @@
+# Copyright 2009 Brian Quinlan. All Rights Reserved.
+# Licensed to PSF under a Contributor Agreement.
+
+"""Implements ProcessPoolExecutor.
+
+The follow diagram and text describe the data-flow through the system:
+
+|======================= In-process =====================|== Out-of-process ==|
+
++----------+     +----------+       +--------+     +-----------+    +---------+
+|          |  => | Work Ids |    => |        |  => | Call Q    | => |         |
+|          |     +----------+       |        |     +-----------+    |         |
+|          |     | ...      |       |        |     | ...       |    |         |
+|          |     | 6        |       |        |     | 5, call() |    |         |
+|          |     | 7        |       |        |     | ...       |    |         |
+| Process  |     | ...      |       | Local  |     +-----------+    | Process |
+|  Pool    |     +----------+       | Worker |                      |  #1..n  |
+| Executor |                        | Thread |                      |         |
+|          |     +----------- +     |        |     +-----------+    |         |
+|          | <=> | Work Items | <=> |        | <=  | Result Q  | <= |         |
+|          |     +------------+     |        |     +-----------+    |         |
+|          |     | 6: call()  |     |        |     | ...       |    |         |
+|          |     |    future  |     |        |     | 4, result |    |         |
+|          |     | ...        |     |        |     | 3, except |    |         |
++----------+     +------------+     +--------+     +-----------+    +---------+
+
+Executor.submit() called:
+- creates a uniquely numbered _WorkItem and adds it to the "Work Items" dict
+- adds the id of the _WorkItem to the "Work Ids" queue
+
+Local worker thread:
+- reads work ids from the "Work Ids" queue and looks up the corresponding
+  WorkItem from the "Work Items" dict: if the work item has been cancelled then
+  it is simply removed from the dict, otherwise it is repackaged as a
+  _CallItem and put in the "Call Q". New _CallItems are put in the "Call Q"
+  until "Call Q" is full. NOTE: the size of the "Call Q" is kept small because
+  calls placed in the "Call Q" can no longer be cancelled with Future.cancel().
+- reads _ResultItems from "Result Q", updates the future stored in the
+  "Work Items" dict and deletes the dict entry
+
+Process #1..n:
+- reads _CallItems from "Call Q", executes the calls, and puts the resulting
+  _ResultItems in "Request Q"
+"""
+
+import atexit
+from concurrent.futures import _base
+import Queue as queue
+import multiprocessing
+import threading
+import weakref
+import sys
+
+__author__ = 'Brian Quinlan (brian@sweetapp.com)'
+
+# Workers are created as daemon threads and processes. This is done to allow the
+# interpreter to exit when there are still idle processes in a
+# ProcessPoolExecutor's process pool (i.e. shutdown() was not called). However,
+# allowing workers to die with the interpreter has two undesirable properties:
+#   - The workers would still be running during interpretor shutdown,
+#     meaning that they would fail in unpredictable ways.
+#   - The workers could be killed while evaluating a work item, which could
+#     be bad if the callable being evaluated has external side-effects e.g.
+#     writing to a file.
+#
+# To work around this problem, an exit handler is installed which tells the
+# workers to exit when their work queues are empty and then waits until the
+# threads/processes finish.
+
+_threads_queues = weakref.WeakKeyDictionary()
+_shutdown = False
+
+def _python_exit():
+    global _shutdown
+    _shutdown = True
+    items = list(_threads_queues.items()) if _threads_queues else ()
+    for t, q in items:
+        q.put(None)
+    for t, q in items:
+        t.join(sys.maxint)
+
+# Controls how many more calls than processes will be queued in the call queue.
+# A smaller number will mean that processes spend more time idle waiting for
+# work while a larger number will make Future.cancel() succeed less frequently
+# (Futures in the call queue cannot be cancelled).
+EXTRA_QUEUED_CALLS = 1
+
+class _WorkItem(object):
+    def __init__(self, future, fn, args, kwargs):
+        self.future = future
+        self.fn = fn
+        self.args = args
+        self.kwargs = kwargs
+
+class _ResultItem(object):
+    def __init__(self, work_id, exception=None, result=None):
+        self.work_id = work_id
+        self.exception = exception
+        self.result = result
+
+class _CallItem(object):
+    def __init__(self, work_id, fn, args, kwargs):
+        self.work_id = work_id
+        self.fn = fn
+        self.args = args
+        self.kwargs = kwargs
+
+def _process_worker(call_queue, result_queue):
+    """Evaluates calls from call_queue and places the results in result_queue.
+
+    This worker is run in a separate process.
+
+    Args:
+        call_queue: A multiprocessing.Queue of _CallItems that will be read and
+            evaluated by the worker.
+        result_queue: A multiprocessing.Queue of _ResultItems that will written
+            to by the worker.
+        shutdown: A multiprocessing.Event that will be set as a signal to the
+            worker that it should exit when call_queue is empty.
+    """
+    while True:
+        call_item = call_queue.get(block=True)
+        if call_item is None:
+            # Wake up queue management thread
+            result_queue.put(None)
+            return
+        try:
+            r = call_item.fn(*call_item.args, **call_item.kwargs)
+        except:
+            e = sys.exc_info()[1]
+            result_queue.put(_ResultItem(call_item.work_id,
+                                         exception=e))
+        else:
+            result_queue.put(_ResultItem(call_item.work_id,
+                                         result=r))
+
+def _add_call_item_to_queue(pending_work_items,
+                            work_ids,
+                            call_queue):
+    """Fills call_queue with _WorkItems from pending_work_items.
+
+    This function never blocks.
+
+    Args:
+        pending_work_items: A dict mapping work ids to _WorkItems e.g.
+            {5: <_WorkItem...>, 6: <_WorkItem...>, ...}
+        work_ids: A queue.Queue of work ids e.g. Queue([5, 6, ...]). Work ids
+            are consumed and the corresponding _WorkItems from
+            pending_work_items are transformed into _CallItems and put in
+            call_queue.
+        call_queue: A multiprocessing.Queue that will be filled with _CallItems
+            derived from _WorkItems.
+    """
+    while True:
+        if call_queue.full():
+            return
+        try:
+            work_id = work_ids.get(block=False)
+        except queue.Empty:
+            return
+        else:
+            work_item = pending_work_items[work_id]
+
+            if work_item.future.set_running_or_notify_cancel():
+                call_queue.put(_CallItem(work_id,
+                                         work_item.fn,
+                                         work_item.args,
+                                         work_item.kwargs),
+                               block=True)
+            else:
+                del pending_work_items[work_id]
+                continue
+
+def _queue_management_worker(executor_reference,
+                             processes,
+                             pending_work_items,
+                             work_ids_queue,
+                             call_queue,
+                             result_queue):
+    """Manages the communication between this process and the worker processes.
+
+    This function is run in a local thread.
+
+    Args:
+        executor_reference: A weakref.ref to the ProcessPoolExecutor that owns
+            this thread. Used to determine if the ProcessPoolExecutor has been
+            garbage collected and that this function can exit.
+        process: A list of the multiprocessing.Process instances used as
+            workers.
+        pending_work_items: A dict mapping work ids to _WorkItems e.g.
+            {5: <_WorkItem...>, 6: <_WorkItem...>, ...}
+        work_ids_queue: A queue.Queue of work ids e.g. Queue([5, 6, ...]).
+        call_queue: A multiprocessing.Queue that will be filled with _CallItems
+            derived from _WorkItems for processing by the process workers.
+        result_queue: A multiprocessing.Queue of _ResultItems generated by the
+            process workers.
+    """
+    nb_shutdown_processes = [0]
+    def shutdown_one_process():
+        """Tell a worker to terminate, which will in turn wake us again"""
+        call_queue.put(None)
+        nb_shutdown_processes[0] += 1
+    while True:
+        _add_call_item_to_queue(pending_work_items,
+                                work_ids_queue,
+                                call_queue)
+
+        result_item = result_queue.get(block=True)
+        if result_item is not None:
+            work_item = pending_work_items[result_item.work_id]
+            del pending_work_items[result_item.work_id]
+
+            if result_item.exception:
+                work_item.future.set_exception(result_item.exception)
+            else:
+                work_item.future.set_result(result_item.result)
+            # Delete references to object. See issue16284
+            del work_item
+        # Check whether we should start shutting down.
+        executor = executor_reference()
+        # No more work items can be added if:
+        #   - The interpreter is shutting down OR
+        #   - The executor that owns this worker has been collected OR
+        #   - The executor that owns this worker has been shutdown.
+        if _shutdown or executor is None or executor._shutdown_thread:
+            # Since no new work items can be added, it is safe to shutdown
+            # this thread if there are no pending work items.
+            if not pending_work_items:
+                while nb_shutdown_processes[0] < len(processes):
+                    shutdown_one_process()
+                # If .join() is not called on the created processes then
+                # some multiprocessing.Queue methods may deadlock on Mac OS
+                # X.
+                for p in processes:
+                    p.join()
+                call_queue.close()
+                return
+        del executor
+
+_system_limits_checked = False
+_system_limited = None
+def _check_system_limits():
+    global _system_limits_checked, _system_limited
+    if _system_limits_checked:
+        if _system_limited:
+            raise NotImplementedError(_system_limited)
+    _system_limits_checked = True
+    try:
+        import os
+        nsems_max = os.sysconf("SC_SEM_NSEMS_MAX")
+    except (AttributeError, ValueError):
+        # sysconf not available or setting not available
+        return
+    if nsems_max == -1:
+        # indetermine limit, assume that limit is determined
+        # by available memory only
+        return
+    if nsems_max >= 256:
+        # minimum number of semaphores available
+        # according to POSIX
+        return
+    _system_limited = "system provides too few semaphores (%d available, 256 necessary)" % nsems_max
+    raise NotImplementedError(_system_limited)
+
+
+class ProcessPoolExecutor(_base.Executor):
+    def __init__(self, max_workers=None):
+        """Initializes a new ProcessPoolExecutor instance.
+
+        Args:
+            max_workers: The maximum number of processes that can be used to
+                execute the given calls. If None or not given then as many
+                worker processes will be created as the machine has processors.
+        """
+        _check_system_limits()
+
+        if max_workers is None:
+            self._max_workers = multiprocessing.cpu_count()
+        else:
+            if max_workers <= 0:
+                raise ValueError("max_workers must be greater than 0")
+
+            self._max_workers = max_workers
+
+        # Make the call queue slightly larger than the number of processes to
+        # prevent the worker processes from idling. But don't make it too big
+        # because futures in the call queue cannot be cancelled.
+        self._call_queue = multiprocessing.Queue(self._max_workers +
+                                                 EXTRA_QUEUED_CALLS)
+        self._result_queue = multiprocessing.Queue()
+        self._work_ids = queue.Queue()
+        self._queue_management_thread = None
+        self._processes = set()
+
+        # Shutdown is a two-step process.
+        self._shutdown_thread = False
+        self._shutdown_lock = threading.Lock()
+        self._queue_count = 0
+        self._pending_work_items = {}
+
+    def _start_queue_management_thread(self):
+        # When the executor gets lost, the weakref callback will wake up
+        # the queue management thread.
+        def weakref_cb(_, q=self._result_queue):
+            q.put(None)
+        if self._queue_management_thread is None:
+            self._queue_management_thread = threading.Thread(
+                    target=_queue_management_worker,
+                    args=(weakref.ref(self, weakref_cb),
+                          self._processes,
+                          self._pending_work_items,
+                          self._work_ids,
+                          self._call_queue,
+                          self._result_queue))
+            self._queue_management_thread.daemon = True
+            self._queue_management_thread.start()
+            _threads_queues[self._queue_management_thread] = self._result_queue
+
+    def _adjust_process_count(self):
+        for _ in range(len(self._processes), self._max_workers):
+            p = multiprocessing.Process(
+                    target=_process_worker,
+                    args=(self._call_queue,
+                          self._result_queue))
+            p.start()
+            self._processes.add(p)
+
+    def submit(self, fn, *args, **kwargs):
+        with self._shutdown_lock:
+            if self._shutdown_thread:
+                raise RuntimeError('cannot schedule new futures after shutdown')
+
+            f = _base.Future()
+            w = _WorkItem(f, fn, args, kwargs)
+
+            self._pending_work_items[self._queue_count] = w
+            self._work_ids.put(self._queue_count)
+            self._queue_count += 1
+            # Wake up queue management thread
+            self._result_queue.put(None)
+
+            self._start_queue_management_thread()
+            self._adjust_process_count()
+            return f
+    submit.__doc__ = _base.Executor.submit.__doc__
+
+    def shutdown(self, wait=True):
+        with self._shutdown_lock:
+            self._shutdown_thread = True
+        if self._queue_management_thread:
+            # Wake up queue management thread
+            self._result_queue.put(None)
+            if wait:
+                self._queue_management_thread.join(sys.maxint)
+        # To reduce the risk of openning too many files, remove references to
+        # objects that use file descriptors.
+        self._queue_management_thread = None
+        self._call_queue = None
+        self._result_queue = None
+        self._processes = None
+    shutdown.__doc__ = _base.Executor.shutdown.__doc__
+
+atexit.register(_python_exit)
diff --git a/concurrent/futures/thread.py b/concurrent/futures/thread.py
new file mode 100644
index 0000000..bb0ce9d
--- /dev/null
+++ b/concurrent/futures/thread.py
@@ -0,0 +1,160 @@
+# Copyright 2009 Brian Quinlan. All Rights Reserved.
+# Licensed to PSF under a Contributor Agreement.
+
+"""Implements ThreadPoolExecutor."""
+
+import atexit
+from concurrent.futures import _base
+import itertools
+import Queue as queue
+import threading
+import weakref
+import sys
+
+try:
+    from multiprocessing import cpu_count
+except ImportError:
+    # some platforms don't have multiprocessing
+    def cpu_count():
+        return None
+
+__author__ = 'Brian Quinlan (brian@sweetapp.com)'
+
+# Workers are created as daemon threads. This is done to allow the interpreter
+# to exit when there are still idle threads in a ThreadPoolExecutor's thread
+# pool (i.e. shutdown() was not called). However, allowing workers to die with
+# the interpreter has two undesirable properties:
+#   - The workers would still be running during interpretor shutdown,
+#     meaning that they would fail in unpredictable ways.
+#   - The workers could be killed while evaluating a work item, which could
+#     be bad if the callable being evaluated has external side-effects e.g.
+#     writing to a file.
+#
+# To work around this problem, an exit handler is installed which tells the
+# workers to exit when their work queues are empty and then waits until the
+# threads finish.
+
+_threads_queues = weakref.WeakKeyDictionary()
+_shutdown = False
+
+def _python_exit():
+    global _shutdown
+    _shutdown = True
+    items = list(_threads_queues.items()) if _threads_queues else ()
+    for t, q in items:
+        q.put(None)
+    for t, q in items:
+        t.join(sys.maxint)
+
+atexit.register(_python_exit)
+
+class _WorkItem(object):
+    def __init__(self, future, fn, args, kwargs):
+        self.future = future
+        self.fn = fn
+        self.args = args
+        self.kwargs = kwargs
+
+    def run(self):
+        if not self.future.set_running_or_notify_cancel():
+            return
+
+        try:
+            result = self.fn(*self.args, **self.kwargs)
+        except:
+            e, tb = sys.exc_info()[1:]
+            self.future.set_exception_info(e, tb)
+        else:
+            self.future.set_result(result)
+
+def _worker(executor_reference, work_queue):
+    try:
+        while True:
+            work_item = work_queue.get(block=True)
+            if work_item is not None:
+                work_item.run()
+                # Delete references to object. See issue16284
+                del work_item
+                continue
+            executor = executor_reference()
+            # Exit if:
+            #   - The interpreter is shutting down OR
+            #   - The executor that owns the worker has been collected OR
+            #   - The executor that owns the worker has been shutdown.
+            if _shutdown or executor is None or executor._shutdown:
+                # Notice other workers
+                work_queue.put(None)
+                return
+            del executor
+    except:
+        _base.LOGGER.critical('Exception in worker', exc_info=True)
+
+
+class ThreadPoolExecutor(_base.Executor):
+
+    # Used to assign unique thread names when thread_name_prefix is not supplied.
+    _counter = itertools.count().next
+
+    def __init__(self, max_workers=None, thread_name_prefix=''):
+        """Initializes a new ThreadPoolExecutor instance.
+
+        Args:
+            max_workers: The maximum number of threads that can be used to
+                execute the given calls.
+            thread_name_prefix: An optional name prefix to give our threads.
+        """
+        if max_workers is None:
+            # Use this number because ThreadPoolExecutor is often
+            # used to overlap I/O instead of CPU work.
+            max_workers = (cpu_count() or 1) * 5
+        if max_workers <= 0:
+            raise ValueError("max_workers must be greater than 0")
+
+        self._max_workers = max_workers
+        self._work_queue = queue.Queue()
+        self._threads = set()
+        self._shutdown = False
+        self._shutdown_lock = threading.Lock()
+        self._thread_name_prefix = (thread_name_prefix or
+                                    ("ThreadPoolExecutor-%d" % self._counter()))
+
+    def submit(self, fn, *args, **kwargs):
+        with self._shutdown_lock:
+            if self._shutdown:
+                raise RuntimeError('cannot schedule new futures after shutdown')
+
+            f = _base.Future()
+            w = _WorkItem(f, fn, args, kwargs)
+
+            self._work_queue.put(w)
+            self._adjust_thread_count()
+            return f
+    submit.__doc__ = _base.Executor.submit.__doc__
+
+    def _adjust_thread_count(self):
+        # When the executor gets lost, the weakref callback will wake up
+        # the worker threads.
+        def weakref_cb(_, q=self._work_queue):
+            q.put(None)
+        # TODO(bquinlan): Should avoid creating new threads if there are more
+        # idle threads than items in the work queue.
+        num_threads = len(self._threads)
+        if num_threads < self._max_workers:
+            thread_name = '%s_%d' % (self._thread_name_prefix or self,
+                                     num_threads)
+            t = threading.Thread(name=thread_name, target=_worker,
+                                 args=(weakref.ref(self, weakref_cb),
+                                       self._work_queue))
+            t.daemon = True
+            t.start()
+            self._threads.add(t)
+            _threads_queues[t] = self._work_queue
+
+    def shutdown(self, wait=True):
+        with self._shutdown_lock:
+            self._shutdown = True
+            self._work_queue.put(None)
+        if wait:
+            for t in self._threads:
+                t.join(sys.maxint)
+    shutdown.__doc__ = _base.Executor.shutdown.__doc__
diff --git a/crawl.py b/crawl.py
new file mode 100644
index 0000000..86e0af7
--- /dev/null
+++ b/crawl.py
@@ -0,0 +1,74 @@
+"""Compare the speed of downloading URLs sequentially vs. using futures."""
+
+import functools
+import time
+import timeit
+import sys
+
+try:
+    from urllib2 import urlopen
+except ImportError:
+    from urllib.request import urlopen
+
+from concurrent.futures import (as_completed, ThreadPoolExecutor,
+                                ProcessPoolExecutor)
+
+URLS = ['http://www.google.com/',
+        'http://www.apple.com/',
+        'http://www.ibm.com',
+        'http://www.thisurlprobablydoesnotexist.com',
+        'http://www.slashdot.org/',
+        'http://www.python.org/',
+        'http://www.bing.com/',
+        'http://www.facebook.com/',
+        'http://www.yahoo.com/',
+        'http://www.youtube.com/',
+        'http://www.blogger.com/']
+
+def load_url(url, timeout):
+    kwargs = {'timeout': timeout} if sys.version_info >= (2, 6) else {}
+    return urlopen(url, **kwargs).read()
+
+def download_urls_sequential(urls, timeout=60):
+    url_to_content = {}
+    for url in urls:
+        try:
+            url_to_content[url] = load_url(url, timeout=timeout)
+        except:
+            pass
+    return url_to_content
+
+def download_urls_with_executor(urls, executor, timeout=60):
+    try:
+        url_to_content = {}
+        future_to_url = dict((executor.submit(load_url, url, timeout), url)
+                             for url in urls)
+
+        for future in as_completed(future_to_url):
+            try:
+                url_to_content[future_to_url[future]] = future.result()
+            except:
+                pass
+        return url_to_content
+    finally:
+        executor.shutdown()
+
+def main():
+    for name, fn in [('sequential',
+                      functools.partial(download_urls_sequential, URLS)),
+                     ('processes',
+                      functools.partial(download_urls_with_executor,
+                                        URLS,
+                                        ProcessPoolExecutor(10))),
+                     ('threads',
+                      functools.partial(download_urls_with_executor,
+                                        URLS,
+                                        ThreadPoolExecutor(10)))]:
+        sys.stdout.write('%s: ' % name.ljust(12))
+        start = time.time()
+        url_map = fn()
+        sys.stdout.write('%.2f seconds (%d of %d downloaded)\n' %
+                         (time.time() - start, len(url_map), len(URLS)))
+
+if __name__ == '__main__':
+    main()
diff --git a/docs/Makefile b/docs/Makefile
new file mode 100644
index 0000000..f69d840
--- /dev/null
+++ b/docs/Makefile
@@ -0,0 +1,88 @@
+# Makefile for Sphinx documentation
+#
+
+# You can set these variables from the command line.
+SPHINXOPTS    =
+SPHINXBUILD   = sphinx-build
+PAPER         =
+
+# Internal variables.
+PAPEROPT_a4     = -D latex_paper_size=a4
+PAPEROPT_letter = -D latex_paper_size=letter
+ALLSPHINXOPTS   = -d _build/doctrees $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .
+
+.PHONY: help clean html dirhtml pickle json htmlhelp qthelp latex changes linkcheck doctest
+
+help:
+	@echo "Please use \`make <target>' where <target> is one of"
+	@echo "  html      to make standalone HTML files"
+	@echo "  dirhtml   to make HTML files named index.html in directories"
+	@echo "  pickle    to make pickle files"
+	@echo "  json      to make JSON files"
+	@echo "  htmlhelp  to make HTML files and a HTML help project"
+	@echo "  qthelp    to make HTML files and a qthelp project"
+	@echo "  latex     to make LaTeX files, you can set PAPER=a4 or PAPER=letter"
+	@echo "  changes   to make an overview of all changed/added/deprecated items"
+	@echo "  linkcheck to check all external links for integrity"
+	@echo "  doctest   to run all doctests embedded in the documentation (if enabled)"
+
+clean:
+	-rm -rf _build/*
+
+html:
+	$(SPHINXBUILD) -b html $(ALLSPHINXOPTS) _build/html
+	@echo
+	@echo "Build finished. The HTML pages are in _build/html."
+
+dirhtml:
+	$(SPHINXBUILD) -b dirhtml $(ALLSPHINXOPTS) _build/dirhtml
+	@echo
+	@echo "Build finished. The HTML pages are in _build/dirhtml."
+
+pickle:
+	$(SPHINXBUILD) -b pickle $(ALLSPHINXOPTS) _build/pickle
+	@echo
+	@echo "Build finished; now you can process the pickle files."
+
+json:
+	$(SPHINXBUILD) -b json $(ALLSPHINXOPTS) _build/json
+	@echo
+	@echo "Build finished; now you can process the JSON files."
+
+htmlhelp:
+	$(SPHINXBUILD) -b htmlhelp $(ALLSPHINXOPTS) _build/htmlhelp
+	@echo
+	@echo "Build finished; now you can run HTML Help Workshop with the" \
+	      ".hhp project file in _build/htmlhelp."
+
+qthelp:
+	$(SPHINXBUILD) -b qthelp $(ALLSPHINXOPTS) _build/qthelp
+	@echo
+	@echo "Build finished; now you can run "qcollectiongenerator" with the" \
+	      ".qhcp project file in _build/qthelp, like this:"
+	@echo "# qcollectiongenerator _build/qthelp/futures.qhcp"
+	@echo "To view the help file:"
+	@echo "# assistant -collectionFile _build/qthelp/futures.qhc"
+
+latex:
+	$(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) _build/latex
+	@echo
+	@echo "Build finished; the LaTeX files are in _build/latex."
+	@echo "Run \`make all-pdf' or \`make all-ps' in that directory to" \
+	      "run these through (pdf)latex."
+
+changes:
+	$(SPHINXBUILD) -b changes $(ALLSPHINXOPTS) _build/changes
+	@echo
+	@echo "The overview file is in _build/changes."
+
+linkcheck:
+	$(SPHINXBUILD) -b linkcheck $(ALLSPHINXOPTS) _build/linkcheck
+	@echo
+	@echo "Link check complete; look for any errors in the above output " \
+	      "or in _build/linkcheck/output.txt."
+
+doctest:
+	$(SPHINXBUILD) -b doctest $(ALLSPHINXOPTS) _build/doctest
+	@echo "Testing of doctests in the sources finished, look at the " \
+	      "results in _build/doctest/output.txt."
diff --git a/docs/conf.py b/docs/conf.py
new file mode 100644
index 0000000..5cea44c
--- /dev/null
+++ b/docs/conf.py
@@ -0,0 +1,194 @@
+# -*- coding: utf-8 -*-
+#
+# futures documentation build configuration file, created by
+# sphinx-quickstart on Wed Jun  3 19:35:34 2009.
+#
+# This file is execfile()d with the current directory set to its containing dir.
+#
+# Note that not all possible configuration values are present in this
+# autogenerated file.
+#
+# All configuration values have a default; values that are commented out
+# serve to show the default.
+
+import sys, os
+
+# If extensions (or modules to document with autodoc) are in another directory,
+# add these directories to sys.path here. If the directory is relative to the
+# documentation root, use os.path.abspath to make it absolute, like shown here.
+#sys.path.append(os.path.abspath('.'))
+
+# -- General configuration -----------------------------------------------------
+
+# Add any Sphinx extension module names here, as strings. They can be extensions
+# coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
+extensions = []
+
+# Add any paths that contain templates here, relative to this directory.
+templates_path = ['_templates']
+
+# The suffix of source filenames.
+source_suffix = '.rst'
+
+# The encoding of source files.
+#source_encoding = 'utf-8'
+
+# The master toctree document.
+master_doc = 'index'
+
+# General information about the project.
+project = u'futures'
+copyright = u'2009-2011, Brian Quinlan'
+
+# The version info for the project you're documenting, acts as replacement for
+# |version| and |release|, also used in various other places throughout the
+# built documents.
+#
+# The short X.Y version.
+version = '2.1.6'
+# The full version, including alpha/beta/rc tags.
+release = '2.1.6'
+
+# The language for content autogenerated by Sphinx. Refer to documentation
+# for a list of supported languages.
+#language = None
+
+# There are two options for replacing |today|: either, you set today to some
+# non-false value, then it is used:
+#today = ''
+# Else, today_fmt is used as the format for a strftime call.
+#today_fmt = '%B %d, %Y'
+
+# List of documents that shouldn't be included in the build.
+#unused_docs = []
+
+# List of directories, relative to source directory, that shouldn't be searched
+# for source files.
+exclude_trees = ['_build']
+
+# The reST default role (used for this markup: `text`) to use for all documents.
+#default_role = None
+
+# If true, '()' will be appended to :func: etc. cross-reference text.
+#add_function_parentheses = True
+
+# If true, the current module name will be prepended to all description
+# unit titles (such as .. function::).
+#add_module_names = True
+
+# If true, sectionauthor and moduleauthor directives will be shown in the
+# output. They are ignored by default.
+#show_authors = False
+
+# The name of the Pygments (syntax highlighting) style to use.
+pygments_style = 'sphinx'
+
+# A list of ignored prefixes for module index sorting.
+#modindex_common_prefix = []
+
+
+# -- Options for HTML output ---------------------------------------------------
+
+# The theme to use for HTML and HTML Help pages.  Major themes that come with
+# Sphinx are currently 'default' and 'sphinxdoc'.
+html_theme = 'default'
+
+# Theme options are theme-specific and customize the look and feel of a theme
+# further.  For a list of options available for each theme, see the
+# documentation.
+#html_theme_options = {}
+
+# Add any paths that contain custom themes here, relative to this directory.
+#html_theme_path = []
+
+# The name for this set of Sphinx documents.  If None, it defaults to
+# "<project> v<release> documentation".
+#html_title = None
+
+# A shorter title for the navigation bar.  Default is the same as html_title.
+#html_short_title = None
+
+# The name of an image file (relative to this directory) to place at the top
+# of the sidebar.
+#html_logo = None
+
+# The name of an image file (within the static path) to use as favicon of the
+# docs.  This file should be a Windows icon file (.ico) being 16x16 or 32x32
+# pixels large.
+#html_favicon = None
+
+# Add any paths that contain custom static files (such as style sheets) here,
+# relative to this directory. They are copied after the builtin static files,
+# so a file named "default.css" will overwrite the builtin "default.css".
+html_static_path = ['_static']
+
+# If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
+# using the given strftime format.
+#html_last_updated_fmt = '%b %d, %Y'
+
+# If true, SmartyPants will be used to convert quotes and dashes to
+# typographically correct entities.
+#html_use_smartypants = True
+
+# Custom sidebar templates, maps document names to template names.
+#html_sidebars = {}
+
+# Additional templates that should be rendered to pages, maps page names to
+# template names.
+#html_additional_pages = {}
+
+# If false, no module index is generated.
+#html_use_modindex = True
+
+# If false, no index is generated.
+#html_use_index = True
+
+# If true, the index is split into individual pages for each letter.
+#html_split_index = False
+
+# If true, links to the reST sources are added to the pages.
+#html_show_sourcelink = True
+
+# If true, an OpenSearch description file will be output, and all pages will
+# contain a <link> tag referring to it.  The value of this option must be the
+# base URL from which the finished HTML is served.
+#html_use_opensearch = ''
+
+# If nonempty, this is the file name suffix for HTML files (e.g. ".xhtml").
+#html_file_suffix = ''
+
+# Output file base name for HTML help builder.
+htmlhelp_basename = 'futuresdoc'
+
+
+# -- Options for LaTeX output --------------------------------------------------
+
+# The paper size ('letter' or 'a4').
+#latex_paper_size = 'letter'
+
+# The font size ('10pt', '11pt' or '12pt').
+#latex_font_size = '10pt'
+
+# Grouping the document tree into LaTeX files. List of tuples
+# (source start file, target name, title, author, documentclass [howto/manual]).
+latex_documents = [
+  ('index', 'futures.tex', u'futures Documentation',
+   u'Brian Quinlan', 'manual'),
+]
+
+# The name of an image file (relative to this directory) to place at the top of
+# the title page.
+#latex_logo = None
+
+# For "manual" documents, if this is true, then toplevel headings are parts,
+# not chapters.
+#latex_use_parts = False
+
+# Additional stuff for the LaTeX preamble.
+#latex_preamble = ''
+
+# Documents to append as an appendix to all manuals.
+#latex_appendices = []
+
+# If false, no module index is generated.
+#latex_use_modindex = True
diff --git a/docs/index.rst b/docs/index.rst
new file mode 100644
index 0000000..d74cade
--- /dev/null
+++ b/docs/index.rst
@@ -0,0 +1,347 @@
+:mod:`concurrent.futures` --- Asynchronous computation
+======================================================
+
+.. module:: concurrent.futures
+   :synopsis: Execute computations asynchronously using threads or processes. 
+
+The :mod:`concurrent.futures` module provides a high-level interface for
+asynchronously executing callables.
+
+The asynchronous execution can be be performed by threads using
+:class:`ThreadPoolExecutor` or separate processes using
+:class:`ProcessPoolExecutor`. Both implement the same interface, which is
+defined by the abstract :class:`Executor` class.
+
+Executor Objects
+----------------
+
+:class:`Executor` is an abstract class that provides methods to execute calls
+asynchronously. It should not be used directly, but through its two
+subclasses: :class:`ThreadPoolExecutor` and :class:`ProcessPoolExecutor`.
+
+.. method:: Executor.submit(fn, *args, **kwargs)
+
+   Schedules the callable to be executed as *fn*(*\*args*, *\*\*kwargs*) and
+   returns a :class:`Future` representing the execution of the callable.
+
+::
+
+    with ThreadPoolExecutor(max_workers=1) as executor:
+        future = executor.submit(pow, 323, 1235)
+        print(future.result())
+
+.. method:: Executor.map(func, *iterables, timeout=None)
+
+   Equivalent to map(*func*, *\*iterables*) but func is executed asynchronously
+   and several calls to *func* may be made concurrently. The returned iterator
+   raises a :exc:`TimeoutError` if :meth:`__next__()` is called and the result
+   isn't available after *timeout* seconds from the original call to
+   :meth:`map()`. *timeout* can be an int or float. If *timeout* is not
+   specified or ``None`` then there is no limit to the wait time. If a call
+   raises an exception then that exception will be raised when its value is
+   retrieved from the iterator.
+
+.. method:: Executor.shutdown(wait=True)
+
+   Signal the executor that it should free any resources that it is using when
+   the currently pending futures are done executing. Calls to
+   :meth:`Executor.submit` and :meth:`Executor.map` made after shutdown will
+   raise :exc:`RuntimeError`.
+
+   If *wait* is `True` then this method will not return until all the pending
+   futures are done executing and the resources associated with the executor
+   have been freed. If *wait* is `False` then this method will return
+   immediately and the resources associated with the executor will be freed
+   when all pending futures are done executing. Regardless of the value of
+   *wait*, the entire Python program will not exit until all pending futures
+   are done executing.
+
+   You can avoid having to call this method explicitly if you use the `with`
+   statement, which will shutdown the `Executor` (waiting as if
+   `Executor.shutdown` were called with *wait* set to `True`):
+
+::
+
+    import shutil
+    with ThreadPoolExecutor(max_workers=4) as e:
+        e.submit(shutil.copy, 'src1.txt', 'dest1.txt')
+        e.submit(shutil.copy, 'src2.txt', 'dest2.txt')
+        e.submit(shutil.copy, 'src3.txt', 'dest3.txt')
+        e.submit(shutil.copy, 'src3.txt', 'dest4.txt')
+
+
+ThreadPoolExecutor Objects
+--------------------------
+
+The :class:`ThreadPoolExecutor` class is an :class:`Executor` subclass that uses
+a pool of threads to execute calls asynchronously.
+
+Deadlock can occur when the callable associated with a :class:`Future` waits on
+the results of another :class:`Future`. For example:
+
+::
+
+    import time
+    def wait_on_b():
+        time.sleep(5)
+        print(b.result())  # b will never complete because it is waiting on a.
+        return 5
+
+    def wait_on_a():
+        time.sleep(5)
+        print(a.result())  # a will never complete because it is waiting on b.
+        return 6
+
+
+    executor = ThreadPoolExecutor(max_workers=2)
+    a = executor.submit(wait_on_b)
+    b = executor.submit(wait_on_a)
+
+And:
+
+::
+
+    def wait_on_future():
+        f = executor.submit(pow, 5, 2)
+        # This will never complete because there is only one worker thread and
+        # it is executing this function.
+        print(f.result())
+    
+    executor = ThreadPoolExecutor(max_workers=1)
+    executor.submit(wait_on_future)
+
+.. class:: ThreadPoolExecutor(max_workers)
+
+   Executes calls asynchronously using a pool of at most *max_workers* threads.
+
+.. _threadpoolexecutor-example:
+
+ThreadPoolExecutor Example
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+::
+
+    from concurrent import futures
+    import urllib.request
+    
+    URLS = ['http://www.foxnews.com/',
+            'http://www.cnn.com/',
+            'http://europe.wsj.com/',
+            'http://www.bbc.co.uk/',
+            'http://some-made-up-domain.com/']
+    
+    def load_url(url, timeout):
+        return urllib.request.urlopen(url, timeout=timeout).read()
+    
+    with futures.ThreadPoolExecutor(max_workers=5) as executor:
+        future_to_url = dict((executor.submit(load_url, url, 60), url)
+                             for url in URLS)
+    
+        for future in futures.as_completed(future_to_url):
+            url = future_to_url[future]
+            if future.exception() is not None:
+                print('%r generated an exception: %s' % (url,
+                                                         future.exception()))
+            else:
+                print('%r page is %d bytes' % (url, len(future.result())))
+
+ProcessPoolExecutor Objects
+---------------------------
+
+The :class:`ProcessPoolExecutor` class is an :class:`Executor` subclass that
+uses a pool of processes to execute calls asynchronously.
+:class:`ProcessPoolExecutor` uses the :mod:`multiprocessing` module, which
+allows it to side-step the :term:`Global Interpreter Lock` but also means that
+only picklable objects can be executed and returned.
+
+Calling :class:`Executor` or :class:`Future` methods from a callable submitted
+to a :class:`ProcessPoolExecutor` will result in deadlock.
+
+.. class:: ProcessPoolExecutor(max_workers=None)
+
+   Executes calls asynchronously using a pool of at most *max_workers*
+   processes. If *max_workers* is ``None`` or not given then as many worker
+   processes will be created as the machine has processors.
+
+.. _processpoolexecutor-example:
+
+ProcessPoolExecutor Example
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+::
+
+   import math
+
+   PRIMES = [
+       112272535095293,
+       112582705942171,
+       112272535095293,
+       115280095190773,
+       115797848077099,
+       1099726899285419]
+
+   def is_prime(n):
+       if n % 2 == 0:
+           return False
+
+       sqrt_n = int(math.floor(math.sqrt(n)))
+       for i in range(3, sqrt_n + 1, 2):
+           if n % i == 0:
+               return False
+       return True
+
+   def main():
+       with futures.ProcessPoolExecutor() as executor:
+           for number, prime in zip(PRIMES, executor.map(is_prime, PRIMES)):
+               print('%d is prime: %s' % (number, prime))
+
+   if __name__ == '__main__':
+       main()
+
+Future Objects
+--------------
+
+The :class:`Future` class encapulates the asynchronous execution of a callable.
+:class:`Future` instances are created by :meth:`Executor.submit`.
+
+.. method:: Future.cancel()
+
+   Attempt to cancel the call. If the call is currently being executed then
+   it cannot be cancelled and the method will return `False`, otherwise the call
+   will be cancelled and the method will return `True`.
+
+.. method:: Future.cancelled()
+
+   Return `True` if the call was successfully cancelled.
+
+.. method:: Future.running()
+
+   Return `True` if the call is currently being executed and cannot be
+   cancelled.
+
+.. method:: Future.done()
+
+   Return `True` if the call was successfully cancelled or finished running.
+
+.. method:: Future.result(timeout=None)
+
+   Return the value returned by the call. If the call hasn't yet completed then
+   this method will wait up to *timeout* seconds. If the call hasn't completed
+   in *timeout* seconds then a :exc:`TimeoutError` will be raised. *timeout* can
+   be an int or float.If *timeout* is not specified or ``None`` then there is no
+   limit to the wait time.
+
+   If the future is cancelled before completing then :exc:`CancelledError` will
+   be raised.
+
+   If the call raised then this method will raise the same exception.
+
+.. method:: Future.exception(timeout=None)
+
+   Return the exception raised by the call. If the call hasn't yet completed
+   then this method will wait up to *timeout* seconds. If the call hasn't
+   completed in *timeout* seconds then a :exc:`TimeoutError` will be raised.
+   *timeout* can be an int or float. If *timeout* is not specified or ``None``
+   then there is no limit to the wait time.
+
+   If the future is cancelled before completing then :exc:`CancelledError` will
+   be raised.
+
+   If the call completed without raising then ``None`` is returned.   
+
+.. method:: Future.add_done_callback(fn)
+
+   Attaches the callable *fn* to the future. *fn* will be called, with the
+   future as its only argument, when the future is cancelled or finishes
+   running.
+
+   Added callables are called in the order that they were added and are always
+   called in a thread belonging to the process that added them. If the callable
+   raises an :exc:`Exception` then it will be logged and ignored. If the
+   callable raises another :exc:`BaseException` then the behavior is not
+   defined.
+
+   If the future has already completed or been cancelled then *fn* will be
+   called immediately.
+
+Internal Future Methods
+^^^^^^^^^^^^^^^^^^^^^^^
+
+The following :class:`Future` methods are meant for use in unit tests and
+:class:`Executor` implementations.
+
+.. method:: Future.set_running_or_notify_cancel()
+
+   This method should only be called by :class:`Executor` implementations before
+   executing the work associated with the :class:`Future` and by unit tests.
+
+   If the method returns `False` then the :class:`Future` was cancelled i.e.
+   :meth:`Future.cancel` was called and returned `True`. Any threads waiting
+   on the :class:`Future` completing (i.e. through :func:`as_completed` or
+   :func:`wait`) will be woken up.
+
+   If the method returns `True` then the :class:`Future` was not cancelled
+   and has been put in the running state i.e. calls to
+   :meth:`Future.running` will return `True`.
+
+   This method can only be called once and cannot be called after
+   :meth:`Future.set_result` or :meth:`Future.set_exception` have been
+   called.
+
+.. method:: Future.set_result(result)
+
+   Sets the result of the work associated with the :class:`Future` to *result*.
+
+   This method should only be used by Executor implementations and unit tests.
+
+.. method:: Future.set_exception(exception)
+
+   Sets the result of the work associated with the :class:`Future` to the
+   :class:`Exception` *exception*.
+
+   This method should only be used by Executor implementations and unit tests.
+
+Module Functions
+----------------
+
+.. function:: wait(fs, timeout=None, return_when=ALL_COMPLETED)
+
+   Wait for the :class:`Future` instances (possibly created by different
+   :class:`Executor` instances) given by *fs*  to complete. Returns a named
+   2-tuple of sets. The first set, named "done", contains the futures that
+   completed (finished or were cancelled) before the wait completed. The second
+   set, named "not_done", contains uncompleted futures.
+
+   *timeout* can be used to control the maximum number of seconds to wait before
+   returning. *timeout* can be an int or float. If *timeout* is not specified or
+   ``None`` then there is no limit to the wait time.
+
+   *return_when* indicates when this function should return. It must be one of
+   the following constants:
+
+      +-----------------------------+----------------------------------------+
+      | Constant                    | Description                            |
+      +=============================+========================================+
+      | :const:`FIRST_COMPLETED`    | The function will return when any      |
+      |                             | future finishes or is cancelled.       |
+      +-----------------------------+----------------------------------------+
+      | :const:`FIRST_EXCEPTION`    | The function will return when any      |
+      |                             | future finishes by raising an          |
+      |                             | exception. If no future raises an      |
+      |                             | exception then it is equivalent to     |
+      |                             | `ALL_COMPLETED`.                       |
+      +-----------------------------+----------------------------------------+
+      | :const:`ALL_COMPLETED`      | The function will return when all      |
+      |                             | futures finish or are cancelled.       |
+      +-----------------------------+----------------------------------------+
+
+.. function:: as_completed(fs, timeout=None)
+
+   Returns an iterator over the :class:`Future` instances (possibly created by
+   different :class:`Executor` instances) given by *fs* that yields futures as
+   they complete (finished or were cancelled). Any futures given by *fs* that
+   are duplicated will be returned once. Any futures that completed
+   before :func:`as_completed` is called will be yielded first.  The returned
+   iterator raises a :exc:`TimeoutError` if :meth:`~iterator.__next__` is
+   called and the result isn't available after *timeout* seconds from the
+   original call to :func:`as_completed`.  *timeout* can be an int or float.
+   If *timeout* is not specified or ``None``, there is no limit to the wait
+   time.
diff --git a/docs/make.bat b/docs/make.bat
new file mode 100644
index 0000000..3e8021b
--- /dev/null
+++ b/docs/make.bat
@@ -0,0 +1,112 @@
+@ECHO OFF
+
+REM Command file for Sphinx documentation
+
+set SPHINXBUILD=sphinx-build
+set ALLSPHINXOPTS=-d _build/doctrees %SPHINXOPTS% .
+if NOT "%PAPER%" == "" (
+	set ALLSPHINXOPTS=-D latex_paper_size=%PAPER% %ALLSPHINXOPTS%
+)
+
+if "%1" == "" goto help
+
+if "%1" == "help" (
+	:help
+	echo.Please use `make ^<target^>` where ^<target^> is one of
+	echo.  html      to make standalone HTML files
+	echo.  dirhtml   to make HTML files named index.html in directories
+	echo.  pickle    to make pickle files
+	echo.  json      to make JSON files
+	echo.  htmlhelp  to make HTML files and a HTML help project
+	echo.  qthelp    to make HTML files and a qthelp project
+	echo.  latex     to make LaTeX files, you can set PAPER=a4 or PAPER=letter
+	echo.  changes   to make an overview over all changed/added/deprecated items
+	echo.  linkcheck to check all external links for integrity
+	echo.  doctest   to run all doctests embedded in the documentation if enabled
+	goto end
+)
+
+if "%1" == "clean" (
+	for /d %%i in (_build\*) do rmdir /q /s %%i
+	del /q /s _build\*
+	goto end
+)
+
+if "%1" == "html" (
+	%SPHINXBUILD% -b html %ALLSPHINXOPTS% _build/html
+	echo.
+	echo.Build finished. The HTML pages are in _build/html.
+	goto end
+)
+
+if "%1" == "dirhtml" (
+	%SPHINXBUILD% -b dirhtml %ALLSPHINXOPTS% _build/dirhtml
+	echo.
+	echo.Build finished. The HTML pages are in _build/dirhtml.
+	goto end
+)
+
+if "%1" == "pickle" (
+	%SPHINXBUILD% -b pickle %ALLSPHINXOPTS% _build/pickle
+	echo.
+	echo.Build finished; now you can process the pickle files.
+	goto end
+)
+
+if "%1" == "json" (
+	%SPHINXBUILD% -b json %ALLSPHINXOPTS% _build/json
+	echo.
+	echo.Build finished; now you can process the JSON files.
+	goto end
+)
+
+if "%1" == "htmlhelp" (
+	%SPHINXBUILD% -b htmlhelp %ALLSPHINXOPTS% _build/htmlhelp
+	echo.
+	echo.Build finished; now you can run HTML Help Workshop with the ^
+.hhp project file in _build/htmlhelp.
+	goto end
+)
+
+if "%1" == "qthelp" (
+	%SPHINXBUILD% -b qthelp %ALLSPHINXOPTS% _build/qthelp
+	echo.
+	echo.Build finished; now you can run "qcollectiongenerator" with the ^
+.qhcp project file in _build/qthelp, like this:
+	echo.^> qcollectiongenerator _build\qthelp\futures.qhcp
+	echo.To view the help file:
+	echo.^> assistant -collectionFile _build\qthelp\futures.ghc
+	goto end
+)
+
+if "%1" == "latex" (
+	%SPHINXBUILD% -b latex %ALLSPHINXOPTS% _build/latex
+	echo.
+	echo.Build finished; the LaTeX files are in _build/latex.
+	goto end
+)
+
+if "%1" == "changes" (
+	%SPHINXBUILD% -b changes %ALLSPHINXOPTS% _build/changes
+	echo.
+	echo.The overview file is in _build/changes.
+	goto end
+)
+
+if "%1" == "linkcheck" (
+	%SPHINXBUILD% -b linkcheck %ALLSPHINXOPTS% _build/linkcheck
+	echo.
+	echo.Link check complete; look for any errors in the above output ^
+or in _build/linkcheck/output.txt.
+	goto end
+)
+
+if "%1" == "doctest" (
+	%SPHINXBUILD% -b doctest %ALLSPHINXOPTS% _build/doctest
+	echo.
+	echo.Testing of doctests in the sources finished, look at the ^
+results in _build/doctest/output.txt.
+	goto end
+)
+
+:end
diff --git a/futures.egg-info/PKG-INFO b/futures.egg-info/PKG-INFO
new file mode 100644
index 0000000..e03caec
--- /dev/null
+++ b/futures.egg-info/PKG-INFO
@@ -0,0 +1,52 @@
+Metadata-Version: 1.2
+Name: futures
+Version: 3.2.0
+Summary: Backport of the concurrent.futures package from Python 3
+Home-page: https://github.com/agronholm/pythonfutures
+Author: Alex Grönholm
+Author-email: alex.gronholm@nextday.fi
+License: PSF
+Description: .. image:: https://travis-ci.org/agronholm/pythonfutures.svg?branch=master
+          :target: https://travis-ci.org/agronholm/pythonfutures
+          :alt: Build Status
+        
+        This is a backport of the `concurrent.futures`_ standard library module to Python 2.
+        
+        It should not be installed on Python 3, although there should be no harm in doing so, as the
+        standard library takes precedence over third party libraries.
+        
+        To conditionally require this library only on Python 2, you can do this in your ``setup.py``:
+        
+        .. code-block:: python
+        
+            setup(
+                ...
+                extras_require={
+                    ':python_version == "2.7"': ['futures']
+                }
+            )
+        
+        Or, using the newer syntax:
+        
+        .. code-block:: python
+        
+            setup(
+                ...
+                install_requires={
+                    'futures; python_version == "2.7"'
+                }
+            )
+        
+        .. warning:: The ``ProcessPoolExecutor`` class has known (unfixable) problems on Python 2 and
+          should not be relied on for mission critical work.
+        
+        .. _concurrent.futures: https://docs.python.org/library/concurrent.futures.html
+        
+Platform: UNKNOWN
+Classifier: License :: OSI Approved :: Python Software Foundation License
+Classifier: Development Status :: 5 - Production/Stable
+Classifier: Intended Audience :: Developers
+Classifier: Programming Language :: Python :: 2.6
+Classifier: Programming Language :: Python :: 2.7
+Classifier: Programming Language :: Python :: 2 :: Only
+Requires-Python: >=2.6, <3
diff --git a/futures.egg-info/SOURCES.txt b/futures.egg-info/SOURCES.txt
new file mode 100644
index 0000000..74f5f72
--- /dev/null
+++ b/futures.egg-info/SOURCES.txt
@@ -0,0 +1,23 @@
+LICENSE
+MANIFEST.in
+README.rst
+crawl.py
+primes.py
+setup.cfg
+setup.py
+test_futures.py
+tox.ini
+concurrent/__init__.py
+concurrent/futures/__init__.py
+concurrent/futures/_base.py
+concurrent/futures/process.py
+concurrent/futures/thread.py
+docs/Makefile
+docs/conf.py
+docs/index.rst
+docs/make.bat
+futures.egg-info/PKG-INFO
+futures.egg-info/SOURCES.txt
+futures.egg-info/dependency_links.txt
+futures.egg-info/not-zip-safe
+futures.egg-info/top_level.txt
\ No newline at end of file
diff --git a/futures.egg-info/dependency_links.txt b/futures.egg-info/dependency_links.txt
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/futures.egg-info/dependency_links.txt
@@ -0,0 +1 @@
+
diff --git a/futures.egg-info/not-zip-safe b/futures.egg-info/not-zip-safe
new file mode 100644
index 0000000..8b13789
--- /dev/null
+++ b/futures.egg-info/not-zip-safe
@@ -0,0 +1 @@
+
diff --git a/futures.egg-info/top_level.txt b/futures.egg-info/top_level.txt
new file mode 100644
index 0000000..e4d7bdc
--- /dev/null
+++ b/futures.egg-info/top_level.txt
@@ -0,0 +1 @@
+concurrent
diff --git a/primes.py b/primes.py
new file mode 100644
index 0000000..0da2b3e
--- /dev/null
+++ b/primes.py
@@ -0,0 +1,50 @@
+from __future__ import with_statement
+import math
+import time
+import sys
+
+from concurrent.futures import ThreadPoolExecutor, ProcessPoolExecutor
+
+PRIMES = [
+    112272535095293,
+    112582705942171,
+    112272535095293,
+    115280095190773,
+    115797848077099,
+    117450548693743,
+    993960000099397]
+
+def is_prime(n):
+    if n % 2 == 0:
+        return False
+
+    sqrt_n = int(math.floor(math.sqrt(n)))
+    for i in range(3, sqrt_n + 1, 2):
+        if n % i == 0:
+            return False
+    return True
+
+def sequential():
+    return list(map(is_prime, PRIMES))
+
+def with_process_pool_executor():
+    with ProcessPoolExecutor(10) as executor:
+        return list(executor.map(is_prime, PRIMES))
+
+def with_thread_pool_executor():
+    with ThreadPoolExecutor(10) as executor:
+        return list(executor.map(is_prime, PRIMES))
+
+def main():
+    for name, fn in [('sequential', sequential),
+                     ('processes', with_process_pool_executor),
+                     ('threads', with_thread_pool_executor)]:
+        sys.stdout.write('%s: ' % name.ljust(12))
+        start = time.time()
+        if fn() != [True] * len(PRIMES):
+            sys.stdout.write('failed\n')
+        else:
+            sys.stdout.write('%.2f seconds\n' % (time.time() - start))
+
+if __name__ == '__main__':
+    main()
diff --git a/setup.cfg b/setup.cfg
new file mode 100644
index 0000000..50bb6ac
--- /dev/null
+++ b/setup.cfg
@@ -0,0 +1,11 @@
+[build_sphinx]
+source-dir = docs
+build-dir = build/sphinx
+
+[upload_docs]
+upload-dir = build/sphinx/html
+
+[egg_info]
+tag_build = 
+tag_date = 0
+
diff --git a/setup.py b/setup.py
new file mode 100755
index 0000000..d45e66d
--- /dev/null
+++ b/setup.py
@@ -0,0 +1,42 @@
+#!/usr/bin/env python
+# coding: utf-8
+from warnings import warn
+import os.path
+import sys
+
+if sys.version_info[0] > 2:
+    warn('This backport is meant only for Python 2.\n'
+         'Python 3 users do not need it, as the concurrent.futures '
+         'package is available in the standard library.')
+
+extras = {}
+try:
+    from setuptools import setup
+    extras['zip_safe'] = False
+except ImportError:
+    from distutils.core import setup
+
+here = os.path.dirname(__file__)
+with open(os.path.join(here, 'README.rst')) as f:
+    readme = f.read()
+
+setup(name='futures',
+      version='3.2.0',
+      description='Backport of the concurrent.futures package from Python 3',
+      long_description=readme,
+      author='Brian Quinlan',
+      author_email='brian@sweetapp.com',
+      maintainer=u'Alex Grönholm',
+      maintainer_email='alex.gronholm@nextday.fi',
+      url='https://github.com/agronholm/pythonfutures',
+      packages=['concurrent', 'concurrent.futures'],
+      python_requires='>=2.6, <3',
+      license='PSF',
+      classifiers=['License :: OSI Approved :: Python Software Foundation License',
+                   'Development Status :: 5 - Production/Stable',
+                   'Intended Audience :: Developers',
+                   'Programming Language :: Python :: 2.6',
+                   'Programming Language :: Python :: 2.7',
+                   'Programming Language :: Python :: 2 :: Only'],
+      **extras
+      )
diff --git a/test_futures.py b/test_futures.py
new file mode 100644
index 0000000..d5b3499
--- /dev/null
+++ b/test_futures.py
@@ -0,0 +1,804 @@
+import os
+import subprocess
+import sys
+import threading
+import functools
+import contextlib
+import logging
+import re
+import time
+import gc
+import traceback
+from StringIO import StringIO
+from test import test_support
+
+from concurrent import futures
+from concurrent.futures._base import (
+    PENDING, RUNNING, CANCELLED, CANCELLED_AND_NOTIFIED, FINISHED, Future)
+from concurrent.futures.thread import cpu_count
+
+try:
+    import unittest2 as unittest
+except ImportError:
+    import unittest
+
+
+def reap_threads(func):
+    """Use this function when threads are being used.  This will
+    ensure that the threads are cleaned up even when the test fails.
+    If threading is unavailable this function does nothing.
+    """
+    @functools.wraps(func)
+    def decorator(*args):
+        key = test_support.threading_setup()
+        try:
+            return func(*args)
+        finally:
+            test_support.threading_cleanup(*key)
+    return decorator
+
+
+# Executing the interpreter in a subprocess
+def _assert_python(expected_success, *args, **env_vars):
+    cmd_line = [sys.executable]
+    if not env_vars:
+        cmd_line.append('-E')
+    # Need to preserve the original environment, for in-place testing of
+    # shared library builds.
+    env = os.environ.copy()
+    # But a special flag that can be set to override -- in this case, the
+    # caller is responsible to pass the full environment.
+    if env_vars.pop('__cleanenv', None):
+        env = {}
+    env.update(env_vars)
+    cmd_line.extend(args)
+    p = subprocess.Popen(cmd_line, stdin=subprocess.PIPE,
+                         stdout=subprocess.PIPE, stderr=subprocess.PIPE,
+                         env=env)
+    try:
+        out, err = p.communicate()
+    finally:
+        subprocess._cleanup()
+        p.stdout.close()
+        p.stderr.close()
+    rc = p.returncode
+    err = strip_python_stderr(err)
+    if (rc and expected_success) or (not rc and not expected_success):
+        raise AssertionError(
+            "Process return code is %d, "
+            "stderr follows:\n%s" % (rc, err.decode('ascii', 'ignore')))
+    return rc, out, err
+
+
+def assert_python_ok(*args, **env_vars):
+    """
+    Assert that running the interpreter with `args` and optional environment
+    variables `env_vars` is ok and return a (return code, stdout, stderr) tuple.
+    """
+    return _assert_python(True, *args, **env_vars)
+
+
+def strip_python_stderr(stderr):
+    """Strip the stderr of a Python process from potential debug output
+    emitted by the interpreter.
+
+    This will typically be run on the result of the communicate() method
+    of a subprocess.Popen object.
+    """
+    stderr = re.sub(r"\[\d+ refs\]\r?\n?$".encode(), "".encode(), stderr).strip()
+    return stderr
+
+
+@contextlib.contextmanager
+def captured_stderr():
+    """Return a context manager used by captured_stdout/stdin/stderr
+    that temporarily replaces the sys stream *stream_name* with a StringIO."""
+    logging_stream = StringIO()
+    handler = logging.StreamHandler(logging_stream)
+    logging.root.addHandler(handler)
+
+    try:
+        yield logging_stream
+    finally:
+        logging.root.removeHandler(handler)
+
+
+def create_future(state=PENDING, exception=None, result=None):
+    f = Future()
+    f._state = state
+    f._exception = exception
+    f._result = result
+    return f
+
+
+PENDING_FUTURE = create_future(state=PENDING)
+RUNNING_FUTURE = create_future(state=RUNNING)
+CANCELLED_FUTURE = create_future(state=CANCELLED)
+CANCELLED_AND_NOTIFIED_FUTURE = create_future(state=CANCELLED_AND_NOTIFIED)
+EXCEPTION_FUTURE = create_future(state=FINISHED, exception=IOError())
+SUCCESSFUL_FUTURE = create_future(state=FINISHED, result=42)
+
+
+def mul(x, y):
+    return x * y
+
+
+def sleep_and_raise(t):
+    time.sleep(t)
+    raise Exception('this is an exception')
+
+def sleep_and_print(t, msg):
+    time.sleep(t)
+    print(msg)
+    sys.stdout.flush()
+
+
+class ExecutorMixin:
+    worker_count = 5
+
+    def setUp(self):
+        self.t1 = time.time()
+        try:
+            self.executor = self.executor_type(max_workers=self.worker_count)
+        except NotImplementedError:
+            e = sys.exc_info()[1]
+            self.skipTest(str(e))
+        self._prime_executor()
+
+    def tearDown(self):
+        self.executor.shutdown(wait=True)
+        dt = time.time() - self.t1
+        if test_support.verbose:
+            print("%.2fs" % dt)
+        self.assertLess(dt, 60, "synchronization issue: test lasted too long")
+
+    def _prime_executor(self):
+        # Make sure that the executor is ready to do work before running the
+        # tests. This should reduce the probability of timeouts in the tests.
+        futures = [self.executor.submit(time.sleep, 0.1)
+                   for _ in range(self.worker_count)]
+
+        for f in futures:
+            f.result()
+
+
+class ThreadPoolMixin(ExecutorMixin):
+    executor_type = futures.ThreadPoolExecutor
+
+
+class ProcessPoolMixin(ExecutorMixin):
+    executor_type = futures.ProcessPoolExecutor
+
+
+class ExecutorShutdownTest(unittest.TestCase):
+    def test_run_after_shutdown(self):
+        self.executor.shutdown()
+        self.assertRaises(RuntimeError,
+                          self.executor.submit,
+                          pow, 2, 5)
+
+    def test_interpreter_shutdown(self):
+        # Test the atexit hook for shutdown of worker threads and processes
+        rc, out, err = assert_python_ok('-c', """if 1:
+            from concurrent.futures import %s
+            from time import sleep
+            from test_futures import sleep_and_print
+            t = %s(5)
+            t.submit(sleep_and_print, 1.0, "apple")
+            """ % (self.executor_type.__name__, self.executor_type.__name__))
+        # Errors in atexit hooks don't change the process exit code, check
+        # stderr manually.
+        self.assertFalse(err)
+        self.assertEqual(out.strip(), "apple".encode())
+
+    def test_hang_issue12364(self):
+        fs = [self.executor.submit(time.sleep, 0.1) for _ in range(50)]
+        self.executor.shutdown()
+        for f in fs:
+            f.result()
+
+
+class ThreadPoolShutdownTest(ThreadPoolMixin, ExecutorShutdownTest):
+    def _prime_executor(self):
+        pass
+
+    def test_threads_terminate(self):
+        self.executor.submit(mul, 21, 2)
+        self.executor.submit(mul, 6, 7)
+        self.executor.submit(mul, 3, 14)
+        self.assertEqual(len(self.executor._threads), 3)
+        self.executor.shutdown()
+        for t in self.executor._threads:
+            t.join()
+
+    def test_context_manager_shutdown(self):
+        with futures.ThreadPoolExecutor(max_workers=5) as e:
+            executor = e
+            self.assertEqual(list(e.map(abs, range(-5, 5))),
+                             [5, 4, 3, 2, 1, 0, 1, 2, 3, 4])
+
+        for t in executor._threads:
+            t.join()
+
+    def test_del_shutdown(self):
+        executor = futures.ThreadPoolExecutor(max_workers=5)
+        executor.map(abs, range(-5, 5))
+        threads = executor._threads
+        del executor
+        gc.collect()
+
+        for t in threads:
+            t.join()
+
+    def test_thread_names_assigned(self):
+        executor = futures.ThreadPoolExecutor(
+            max_workers=5, thread_name_prefix='SpecialPool')
+        executor.map(abs, range(-5, 5))
+        threads = executor._threads
+        del executor
+        gc.collect()
+
+        for t in threads:
+            self.assertRegexpMatches(t.name, r'^SpecialPool_[0-4]$')
+            t.join()
+
+    def test_thread_names_default(self):
+        executor = futures.ThreadPoolExecutor(max_workers=5)
+        executor.map(abs, range(-5, 5))
+        threads = executor._threads
+        del executor
+        gc.collect()
+
+        for t in threads:
+            # Ensure that our default name is reasonably sane and unique when
+            # no thread_name_prefix was supplied.
+            self.assertRegexpMatches(t.name, r'ThreadPoolExecutor-\d+_[0-4]$')
+            t.join()
+
+
+class ProcessPoolShutdownTest(ProcessPoolMixin, ExecutorShutdownTest):
+    def _prime_executor(self):
+        pass
+
+    def test_processes_terminate(self):
+        self.executor.submit(mul, 21, 2)
+        self.executor.submit(mul, 6, 7)
+        self.executor.submit(mul, 3, 14)
+        self.assertEqual(len(self.executor._processes), 5)
+        processes = self.executor._processes
+        self.executor.shutdown()
+
+        for p in processes:
+            p.join()
+
+    def test_context_manager_shutdown(self):
+        with futures.ProcessPoolExecutor(max_workers=5) as e:
+            processes = e._processes
+            self.assertEqual(list(e.map(abs, range(-5, 5))),
+                             [5, 4, 3, 2, 1, 0, 1, 2, 3, 4])
+
+        for p in processes:
+            p.join()
+
+    def test_del_shutdown(self):
+        executor = futures.ProcessPoolExecutor(max_workers=5)
+        list(executor.map(abs, range(-5, 5)))
+        queue_management_thread = executor._queue_management_thread
+        processes = executor._processes
+        del executor
+        gc.collect()
+
+        queue_management_thread.join()
+        for p in processes:
+            p.join()
+
+
+class WaitTests(unittest.TestCase):
+
+    def test_first_completed(self):
+        future1 = self.executor.submit(mul, 21, 2)
+        future2 = self.executor.submit(time.sleep, 1.5)
+
+        done, not_done = futures.wait(
+                [CANCELLED_FUTURE, future1, future2],
+                 return_when=futures.FIRST_COMPLETED)
+
+        self.assertEqual(set([future1]), done)
+        self.assertEqual(set([CANCELLED_FUTURE, future2]), not_done)
+
+    def test_first_completed_some_already_completed(self):
+        future1 = self.executor.submit(time.sleep, 1.5)
+
+        finished, pending = futures.wait(
+                 [CANCELLED_AND_NOTIFIED_FUTURE, SUCCESSFUL_FUTURE, future1],
+                 return_when=futures.FIRST_COMPLETED)
+
+        self.assertEqual(
+                set([CANCELLED_AND_NOTIFIED_FUTURE, SUCCESSFUL_FUTURE]),
+                finished)
+        self.assertEqual(set([future1]), pending)
+
+    def test_first_exception(self):
+        future1 = self.executor.submit(mul, 2, 21)
+        future2 = self.executor.submit(sleep_and_raise, 1.5)
+        future3 = self.executor.submit(time.sleep, 3)
+
+        finished, pending = futures.wait(
+                [future1, future2, future3],
+                return_when=futures.FIRST_EXCEPTION)
+
+        self.assertEqual(set([future1, future2]), finished)
+        self.assertEqual(set([future3]), pending)
+
+    def test_first_exception_some_already_complete(self):
+        future1 = self.executor.submit(divmod, 21, 0)
+        future2 = self.executor.submit(time.sleep, 1.5)
+
+        finished, pending = futures.wait(
+                [SUCCESSFUL_FUTURE,
+                 CANCELLED_FUTURE,
+                 CANCELLED_AND_NOTIFIED_FUTURE,
+                 future1, future2],
+                return_when=futures.FIRST_EXCEPTION)
+
+        self.assertEqual(set([SUCCESSFUL_FUTURE,
+                              CANCELLED_AND_NOTIFIED_FUTURE,
+                              future1]), finished)
+        self.assertEqual(set([CANCELLED_FUTURE, future2]), pending)
+
+    def test_first_exception_one_already_failed(self):
+        future1 = self.executor.submit(time.sleep, 2)
+
+        finished, pending = futures.wait(
+                 [EXCEPTION_FUTURE, future1],
+                 return_when=futures.FIRST_EXCEPTION)
+
+        self.assertEqual(set([EXCEPTION_FUTURE]), finished)
+        self.assertEqual(set([future1]), pending)
+
+    def test_all_completed(self):
+        future1 = self.executor.submit(divmod, 2, 0)
+        future2 = self.executor.submit(mul, 2, 21)
+
+        finished, pending = futures.wait(
+                [SUCCESSFUL_FUTURE,
+                 CANCELLED_AND_NOTIFIED_FUTURE,
+                 EXCEPTION_FUTURE,
+                 future1,
+                 future2],
+                return_when=futures.ALL_COMPLETED)
+
+        self.assertEqual(set([SUCCESSFUL_FUTURE,
+                              CANCELLED_AND_NOTIFIED_FUTURE,
+                              EXCEPTION_FUTURE,
+                              future1,
+                              future2]), finished)
+        self.assertEqual(set(), pending)
+
+    def test_timeout(self):
+        future1 = self.executor.submit(mul, 6, 7)
+        future2 = self.executor.submit(time.sleep, 3)
+
+        finished, pending = futures.wait(
+                [CANCELLED_AND_NOTIFIED_FUTURE,
+                 EXCEPTION_FUTURE,
+                 SUCCESSFUL_FUTURE,
+                 future1, future2],
+                timeout=1.5,
+                return_when=futures.ALL_COMPLETED)
+
+        self.assertEqual(set([CANCELLED_AND_NOTIFIED_FUTURE,
+                              EXCEPTION_FUTURE,
+                              SUCCESSFUL_FUTURE,
+                              future1]), finished)
+        self.assertEqual(set([future2]), pending)
+
+
+class ThreadPoolWaitTests(ThreadPoolMixin, WaitTests):
+
+    def test_pending_calls_race(self):
+        # Issue #14406: multi-threaded race condition when waiting on all
+        # futures.
+        event = threading.Event()
+        def future_func():
+            event.wait()
+        oldswitchinterval = sys.getcheckinterval()
+        sys.setcheckinterval(1)
+        try:
+            fs = set(self.executor.submit(future_func) for i in range(100))
+            event.set()
+            futures.wait(fs, return_when=futures.ALL_COMPLETED)
+        finally:
+            sys.setcheckinterval(oldswitchinterval)
+
+
+class ProcessPoolWaitTests(ProcessPoolMixin, WaitTests):
+    pass
+
+
+class AsCompletedTests(unittest.TestCase):
+    # TODO(brian@sweetapp.com): Should have a test with a non-zero timeout.
+    def test_no_timeout(self):
+        future1 = self.executor.submit(mul, 2, 21)
+        future2 = self.executor.submit(mul, 7, 6)
+
+        completed = set(futures.as_completed(
+                [CANCELLED_AND_NOTIFIED_FUTURE,
+                 EXCEPTION_FUTURE,
+                 SUCCESSFUL_FUTURE,
+                 future1, future2]))
+        self.assertEqual(set(
+                [CANCELLED_AND_NOTIFIED_FUTURE,
+                 EXCEPTION_FUTURE,
+                 SUCCESSFUL_FUTURE,
+                 future1, future2]),
+                completed)
+
+    def test_zero_timeout(self):
+        future1 = self.executor.submit(time.sleep, 2)
+        completed_futures = set()
+        try:
+            for future in futures.as_completed(
+                    [CANCELLED_AND_NOTIFIED_FUTURE,
+                     EXCEPTION_FUTURE,
+                     SUCCESSFUL_FUTURE,
+                     future1],
+                    timeout=0):
+                completed_futures.add(future)
+        except futures.TimeoutError:
+            pass
+
+        self.assertEqual(set([CANCELLED_AND_NOTIFIED_FUTURE,
+                              EXCEPTION_FUTURE,
+                              SUCCESSFUL_FUTURE]),
+                         completed_futures)
+
+    def test_duplicate_futures(self):
+        # Issue 20367. Duplicate futures should not raise exceptions or give
+        # duplicate responses.
+        future1 = self.executor.submit(time.sleep, 2)
+        completed = [f for f in futures.as_completed([future1,future1])]
+        self.assertEqual(len(completed), 1)
+
+
+class ThreadPoolAsCompletedTests(ThreadPoolMixin, AsCompletedTests):
+    pass
+
+
+class ProcessPoolAsCompletedTests(ProcessPoolMixin, AsCompletedTests):
+    pass
+
+
+class ExecutorTest(unittest.TestCase):
+    # Executor.shutdown() and context manager usage is tested by
+    # ExecutorShutdownTest.
+    def test_submit(self):
+        future = self.executor.submit(pow, 2, 8)
+        self.assertEqual(256, future.result())
+
+    def test_submit_keyword(self):
+        future = self.executor.submit(mul, 2, y=8)
+        self.assertEqual(16, future.result())
+
+    def test_map(self):
+        self.assertEqual(
+                list(self.executor.map(pow, range(10), range(10))),
+                list(map(pow, range(10), range(10))))
+
+    def test_map_exception(self):
+        i = self.executor.map(divmod, [1, 1, 1, 1], [2, 3, 0, 5])
+        self.assertEqual(next(i), (0, 1))
+        self.assertEqual(next(i), (0, 1))
+        self.assertRaises(ZeroDivisionError, next, i)
+
+    def test_map_timeout(self):
+        results = []
+        try:
+            for i in self.executor.map(time.sleep,
+                                       [0, 0, 3],
+                                       timeout=1.5):
+                results.append(i)
+        except futures.TimeoutError:
+            pass
+        else:
+            self.fail('expected TimeoutError')
+
+        self.assertEqual([None, None], results)
+
+    def test_max_workers_negative(self):
+        for number in (0, -1):
+            with self.assertRaises(ValueError) as cm:
+                self.executor_type(max_workers=number)
+
+            assert str(cm.exception) == "max_workers must be greater than 0"
+
+
+class ThreadPoolExecutorTest(ThreadPoolMixin, ExecutorTest):
+    def test_map_submits_without_iteration(self):
+        """Tests verifying issue 11777."""
+        finished = []
+        def record_finished(n):
+            finished.append(n)
+
+        self.executor.map(record_finished, range(10))
+        self.executor.shutdown(wait=True)
+        self.assertEqual(len(finished), 10)
+
+    def test_default_workers(self):
+        executor = self.executor_type()
+        self.assertEqual(executor._max_workers,
+                         (cpu_count() or 1) * 5)
+
+
+class ProcessPoolExecutorTest(ProcessPoolMixin, ExecutorTest):
+    pass
+
+
+class FutureTests(unittest.TestCase):
+    def test_done_callback_with_result(self):
+        callback_result = [None]
+        def fn(callback_future):
+            callback_result[0] = callback_future.result()
+
+        f = Future()
+        f.add_done_callback(fn)
+        f.set_result(5)
+        self.assertEqual(5, callback_result[0])
+
+    def test_done_callback_with_exception(self):
+        callback_exception = [None]
+        def fn(callback_future):
+            callback_exception[0] = callback_future.exception()
+
+        f = Future()
+        f.add_done_callback(fn)
+        f.set_exception(Exception('test'))
+        self.assertEqual(('test',), callback_exception[0].args)
+
+    def test_done_callback_with_cancel(self):
+        was_cancelled = [None]
+        def fn(callback_future):
+            was_cancelled[0] = callback_future.cancelled()
+
+        f = Future()
+        f.add_done_callback(fn)
+        self.assertTrue(f.cancel())
+        self.assertTrue(was_cancelled[0])
+
+    def test_done_callback_raises(self):
+        with captured_stderr() as stderr:
+            raising_was_called = [False]
+            raising_old_style_was_called = [False]
+            fn_was_called = [False]
+
+            def raising_fn(callback_future):
+                raising_was_called[0] = True
+                raise Exception('doh!')
+
+            def raising_old_style_fn(callback_future):
+                raising_old_style_was_called[0] = True
+                class OldStyle:  # Does not inherit from object
+                   def __str__(self):
+                       return 'doh!'
+                raise OldStyle()
+
+            def fn(callback_future):
+                fn_was_called[0] = True
+
+            f = Future()
+            f.add_done_callback(raising_fn)
+            f.add_done_callback(raising_old_style_fn)
+            f.add_done_callback(fn)
+            f.set_result(5)
+            self.assertTrue(raising_was_called)
+            self.assertTrue(raising_old_style_was_called)
+            self.assertTrue(fn_was_called)
+            self.assertIn('Exception: doh!', stderr.getvalue())
+            self.assertIn('OldStyle: doh!', stderr.getvalue())
+
+    def test_done_callback_already_successful(self):
+        callback_result = [None]
+        def fn(callback_future):
+            callback_result[0] = callback_future.result()
+
+        f = Future()
+        f.set_result(5)
+        f.add_done_callback(fn)
+        self.assertEqual(5, callback_result[0])
+
+    def test_done_callback_already_failed(self):
+        callback_exception = [None]
+        def fn(callback_future):
+            callback_exception[0] = callback_future.exception()
+
+        f = Future()
+        f.set_exception(Exception('test'))
+        f.add_done_callback(fn)
+        self.assertEqual(('test',), callback_exception[0].args)
+
+    def test_done_callback_already_cancelled(self):
+        was_cancelled = [None]
+        def fn(callback_future):
+            was_cancelled[0] = callback_future.cancelled()
+
+        f = Future()
+        self.assertTrue(f.cancel())
+        f.add_done_callback(fn)
+        self.assertTrue(was_cancelled[0])
+
+    def test_repr(self):
+        self.assertRegexpMatches(repr(PENDING_FUTURE),
+                                 '<Future at 0x[0-9a-f]+L? state=pending>')
+        self.assertRegexpMatches(repr(RUNNING_FUTURE),
+                                 '<Future at 0x[0-9a-f]+L? state=running>')
+        self.assertRegexpMatches(repr(CANCELLED_FUTURE),
+                                 '<Future at 0x[0-9a-f]+L? state=cancelled>')
+        self.assertRegexpMatches(repr(CANCELLED_AND_NOTIFIED_FUTURE),
+                                 '<Future at 0x[0-9a-f]+L? state=cancelled>')
+        self.assertRegexpMatches(
+                repr(EXCEPTION_FUTURE),
+                '<Future at 0x[0-9a-f]+L? state=finished raised IOError>')
+        self.assertRegexpMatches(
+                repr(SUCCESSFUL_FUTURE),
+                '<Future at 0x[0-9a-f]+L? state=finished returned int>')
+
+    def test_cancel(self):
+        f1 = create_future(state=PENDING)
+        f2 = create_future(state=RUNNING)
+        f3 = create_future(state=CANCELLED)
+        f4 = create_future(state=CANCELLED_AND_NOTIFIED)
+        f5 = create_future(state=FINISHED, exception=IOError())
+        f6 = create_future(state=FINISHED, result=5)
+
+        self.assertTrue(f1.cancel())
+        self.assertEqual(f1._state, CANCELLED)
+
+        self.assertFalse(f2.cancel())
+        self.assertEqual(f2._state, RUNNING)
+
+        self.assertTrue(f3.cancel())
+        self.assertEqual(f3._state, CANCELLED)
+
+        self.assertTrue(f4.cancel())
+        self.assertEqual(f4._state, CANCELLED_AND_NOTIFIED)
+
+        self.assertFalse(f5.cancel())
+        self.assertEqual(f5._state, FINISHED)
+
+        self.assertFalse(f6.cancel())
+        self.assertEqual(f6._state, FINISHED)
+
+    def test_cancelled(self):
+        self.assertFalse(PENDING_FUTURE.cancelled())
+        self.assertFalse(RUNNING_FUTURE.cancelled())
+        self.assertTrue(CANCELLED_FUTURE.cancelled())
+        self.assertTrue(CANCELLED_AND_NOTIFIED_FUTURE.cancelled())
+        self.assertFalse(EXCEPTION_FUTURE.cancelled())
+        self.assertFalse(SUCCESSFUL_FUTURE.cancelled())
+
+    def test_done(self):
+        self.assertFalse(PENDING_FUTURE.done())
+        self.assertFalse(RUNNING_FUTURE.done())
+        self.assertTrue(CANCELLED_FUTURE.done())
+        self.assertTrue(CANCELLED_AND_NOTIFIED_FUTURE.done())
+        self.assertTrue(EXCEPTION_FUTURE.done())
+        self.assertTrue(SUCCESSFUL_FUTURE.done())
+
+    def test_running(self):
+        self.assertFalse(PENDING_FUTURE.running())
+        self.assertTrue(RUNNING_FUTURE.running())
+        self.assertFalse(CANCELLED_FUTURE.running())
+        self.assertFalse(CANCELLED_AND_NOTIFIED_FUTURE.running())
+        self.assertFalse(EXCEPTION_FUTURE.running())
+        self.assertFalse(SUCCESSFUL_FUTURE.running())
+
+    def test_result_with_timeout(self):
+        self.assertRaises(futures.TimeoutError,
+                          PENDING_FUTURE.result, timeout=0)
+        self.assertRaises(futures.TimeoutError,
+                          RUNNING_FUTURE.result, timeout=0)
+        self.assertRaises(futures.CancelledError,
+                          CANCELLED_FUTURE.result, timeout=0)
+        self.assertRaises(futures.CancelledError,
+                          CANCELLED_AND_NOTIFIED_FUTURE.result, timeout=0)
+        self.assertRaises(IOError, EXCEPTION_FUTURE.result, timeout=0)
+        self.assertEqual(SUCCESSFUL_FUTURE.result(timeout=0), 42)
+
+    def test_result_with_success(self):
+        # TODO(brian@sweetapp.com): This test is timing dependant.
+        def notification():
+            # Wait until the main thread is waiting for the result.
+            time.sleep(1)
+            f1.set_result(42)
+
+        f1 = create_future(state=PENDING)
+        t = threading.Thread(target=notification)
+        t.start()
+
+        self.assertEqual(f1.result(timeout=5), 42)
+
+    def test_result_with_cancel(self):
+        # TODO(brian@sweetapp.com): This test is timing dependant.
+        def notification():
+            # Wait until the main thread is waiting for the result.
+            time.sleep(1)
+            f1.cancel()
+
+        f1 = create_future(state=PENDING)
+        t = threading.Thread(target=notification)
+        t.start()
+
+        self.assertRaises(futures.CancelledError, f1.result, timeout=5)
+
+    def test_exception_with_timeout(self):
+        self.assertRaises(futures.TimeoutError,
+                          PENDING_FUTURE.exception, timeout=0)
+        self.assertRaises(futures.TimeoutError,
+                          RUNNING_FUTURE.exception, timeout=0)
+        self.assertRaises(futures.CancelledError,
+                          CANCELLED_FUTURE.exception, timeout=0)
+        self.assertRaises(futures.CancelledError,
+                          CANCELLED_AND_NOTIFIED_FUTURE.exception, timeout=0)
+        self.assertTrue(isinstance(EXCEPTION_FUTURE.exception(timeout=0),
+                                   IOError))
+        self.assertEqual(SUCCESSFUL_FUTURE.exception(timeout=0), None)
+
+    def test_exception_with_success(self):
+        def notification():
+            # Wait until the main thread is waiting for the exception.
+            time.sleep(1)
+            with f1._condition:
+                f1._state = FINISHED
+                f1._exception = IOError()
+                f1._condition.notify_all()
+
+        f1 = create_future(state=PENDING)
+        t = threading.Thread(target=notification)
+        t.start()
+
+        self.assertTrue(isinstance(f1.exception(timeout=5), IOError))
+
+    def test_old_style_exception(self):
+        class OldStyle:  # Does not inherit from object
+            def  __str__(self):
+                return 'doh!'
+        callback_exc_info = [None]
+        def fn(callback_future):
+            callback_exc_info[0] = callback_future.exception_info()
+        f = Future()
+        f.add_done_callback(fn)
+        try:
+            raise OldStyle()
+        except OldStyle:
+            want_exc_info = sys.exc_info()
+            f.set_exception_info(*want_exc_info[1:])
+        self.assertEqual(f.exception_info(), want_exc_info[1:])
+        self.assertEqual(callback_exc_info[0], want_exc_info[1:])
+        try:
+            f.result()
+        except OldStyle:
+            got_exc_info = sys.exc_info()
+        else:
+            self.fail('OldStyle exception not raised')
+        self.assertEqual(got_exc_info[:2], want_exc_info[:2])
+        got_tb = traceback.extract_tb(got_exc_info[2])
+        want_tb = traceback.extract_tb(want_exc_info[2])
+        self.assertEqual(got_tb[-len(want_tb):], want_tb)
+
+@reap_threads
+def test_main():
+    try:
+        test_support.run_unittest(ProcessPoolExecutorTest,
+                                  ThreadPoolExecutorTest,
+                                  ProcessPoolWaitTests,
+                                  ThreadPoolWaitTests,
+                                  ProcessPoolAsCompletedTests,
+                                  ThreadPoolAsCompletedTests,
+                                  FutureTests,
+                                  ProcessPoolShutdownTest,
+                                  ThreadPoolShutdownTest)
+    finally:
+        test_support.reap_children()
+
+if __name__ == "__main__":
+    test_main()
diff --git a/tox.ini b/tox.ini
new file mode 100644
index 0000000..fdff7cb
--- /dev/null
+++ b/tox.ini
@@ -0,0 +1,8 @@
+[tox]
+envlist = py26,py27,pypy,jython
+
+[testenv]
+commands = {envpython} test_futures.py {posargs}
+
+[testenv:py26]
+deps = unittest2