"""This test checks for correct fork() behavior. | |
""" | |
import imp | |
import os | |
import signal | |
import sys | |
import time | |
from test.fork_wait import ForkWait | |
from test.test_support import run_unittest, reap_children, get_attribute, import_module | |
threading = import_module('threading') | |
#Skip test if fork does not exist. | |
get_attribute(os, 'fork') | |
class ForkTest(ForkWait): | |
def wait_impl(self, cpid): | |
for i in range(10): | |
# waitpid() shouldn't hang, but some of the buildbots seem to hang | |
# in the forking tests. This is an attempt to fix the problem. | |
spid, status = os.waitpid(cpid, os.WNOHANG) | |
if spid == cpid: | |
break | |
time.sleep(1.0) | |
self.assertEqual(spid, cpid) | |
self.assertEqual(status, 0, "cause = %d, exit = %d" % (status&0xff, status>>8)) | |
def test_import_lock_fork(self): | |
import_started = threading.Event() | |
fake_module_name = "fake test module" | |
partial_module = "partial" | |
complete_module = "complete" | |
def importer(): | |
imp.acquire_lock() | |
sys.modules[fake_module_name] = partial_module | |
import_started.set() | |
time.sleep(0.01) # Give the other thread time to try and acquire. | |
sys.modules[fake_module_name] = complete_module | |
imp.release_lock() | |
t = threading.Thread(target=importer) | |
t.start() | |
import_started.wait() | |
pid = os.fork() | |
try: | |
if not pid: | |
m = __import__(fake_module_name) | |
if m == complete_module: | |
os._exit(0) | |
else: | |
os._exit(1) | |
else: | |
t.join() | |
# Exitcode 1 means the child got a partial module (bad.) No | |
# exitcode (but a hang, which manifests as 'got pid 0') | |
# means the child deadlocked (also bad.) | |
self.wait_impl(pid) | |
finally: | |
try: | |
os.kill(pid, signal.SIGKILL) | |
except OSError: | |
pass | |
def test_main(): | |
run_unittest(ForkTest) | |
reap_children() | |
if __name__ == "__main__": | |
test_main() |