src/hotspot/share/runtime/serviceThread.cpp - platform/libcore - Git at Google

 /*
  * Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */

 #include "precompiled.hpp"
 #include "classfile/stringTable.hpp"
 #include "runtime/interfaceSupport.inline.hpp"
 #include "runtime/javaCalls.hpp"
 #include "runtime/serviceThread.hpp"
 #include "runtime/mutexLocker.hpp"
 #include "runtime/os.hpp"
 #include "prims/jvmtiImpl.hpp"
 #include "services/diagnosticArgument.hpp"
 #include "services/diagnosticFramework.hpp"
 #include "services/gcNotifier.hpp"
 #include "services/lowMemoryDetector.hpp"

 ServiceThread* ServiceThread::_instance = NULL;
 JvmtiDeferredEvent* ServiceThread::_jvmti_event = NULL;
 // The service thread has it's own static deferred event queue.
 // Events can be posted before JVMTI vm_start, so it's too early to call JvmtiThreadState::state_for
 // to add this field to the per-JavaThread event queue.  TODO: fix this sometime later
 JvmtiDeferredEventQueue ServiceThread::_jvmti_service_queue;

 void ServiceThread::initialize() {
   EXCEPTION_MARK;

   const char* name = "Service Thread";
   Handle string = java_lang_String::create_from_str(name, CHECK);

   // Initialize thread_oop to put it into the system threadGroup
   Handle thread_group (THREAD, Universe::system_thread_group());
   Handle thread_oop = JavaCalls::construct_new_instance(
                           SystemDictionary::Thread_klass(),
                           vmSymbols::threadgroup_string_void_signature(),
                           thread_group,
                           string,
                           CHECK);

   {
     MutexLocker mu(Threads_lock);
     ServiceThread* thread =  new ServiceThread(&service_thread_entry);

     // At this point it may be possible that no osthread was created for the
     // JavaThread due to lack of memory. We would have to throw an exception
     // in that case. However, since this must work and we do not allow
     // exceptions anyway, check and abort if this fails.
     if (thread == NULL || thread->osthread() == NULL) {
       vm_exit_during_initialization("java.lang.OutOfMemoryError",
                                     os::native_thread_creation_failed_msg());
     }

     java_lang_Thread::set_thread(thread_oop(), thread);
     java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
     java_lang_Thread::set_daemon(thread_oop());
     thread->set_threadObj(thread_oop());
     _instance = thread;

     Threads::add(thread);
     Thread::start(thread);
   }
 }

 void ServiceThread::service_thread_entry(JavaThread* jt, TRAPS) {
   while (true) {
     bool sensors_changed = false;
     bool has_jvmti_events = false;
     bool has_gc_notification_event = false;
     bool has_dcmd_notification_event = false;
     bool acs_notify = false;
     bool stringtable_work = false;
     JvmtiDeferredEvent jvmti_event;
     {
       // Need state transition ThreadBlockInVM so that this thread
       // will be handled by safepoint correctly when this thread is
       // notified at a safepoint.

       // This ThreadBlockInVM object is not also considered to be
       // suspend-equivalent because ServiceThread is not visible to
       // external suspension.

       ThreadBlockInVM tbivm(jt);

       MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
       while (!(sensors_changed = LowMemoryDetector::has_pending_requests()) &&
              !(has_jvmti_events = _jvmti_service_queue.has_events()) &&
               !(has_gc_notification_event = GCNotifier::has_event()) &&
               !(has_dcmd_notification_event = DCmdFactory::has_pending_jmx_notification()) &&
               !(stringtable_work = StringTable::has_work())) {
         // wait until one of the sensors has pending requests, or there is a
         // pending JVMTI event or JMX GC notification to post
         Service_lock->wait(Mutex::_no_safepoint_check_flag);
       }

       if (has_jvmti_events) {
         // Get the event under the Service_lock
         jvmti_event = _jvmti_service_queue.dequeue();
         _jvmti_event = &jvmti_event;
       }
     }

     if (stringtable_work) {
       StringTable::do_concurrent_work(jt);
     }

     if (has_jvmti_events) {
       _jvmti_event->post();
       _jvmti_event = NULL;  // reset
     }

     if (sensors_changed) {
       LowMemoryDetector::process_sensor_changes(jt);
     }

     if(has_gc_notification_event) {
         GCNotifier::sendNotification(CHECK);
     }

     if(has_dcmd_notification_event) {
       DCmdFactory::send_notification(CHECK);
     }
   }
 }

 void ServiceThread::enqueue_deferred_event(JvmtiDeferredEvent* event) {
   MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
   // If you enqueue events before the service thread runs, gc and the sweeper
   // cannot keep the nmethod alive.  This could be restricted to compiled method
   // load and unload events, if we wanted to be picky.
   assert(_instance != NULL, "cannot enqueue events before the service thread runs");
   _jvmti_service_queue.enqueue(*event);
   Service_lock->notify_all();
  }

 void ServiceThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
   JavaThread::oops_do(f, cf);
   // The ServiceThread "owns" the JVMTI Deferred events, scan them here
   // to keep them alive until they are processed.
   if (cf != NULL) {
     if (_jvmti_event != NULL) {
       _jvmti_event->oops_do(f, cf);
     }
     // Requires a lock, because threads can be adding to this queue.
     MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
     _jvmti_service_queue.oops_do(f, cf);
   }
 }

 void ServiceThread::nmethods_do(CodeBlobClosure* cf) {
   JavaThread::nmethods_do(cf);
   if (cf != NULL) {
     if (_jvmti_event != NULL) {
       _jvmti_event->nmethods_do(cf);
     }
     // Requires a lock, because threads can be adding to this queue.
     MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
     _jvmti_service_queue.nmethods_do(cf);
   }
 }
	/*
	* Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*
	*/

	#include "precompiled.hpp"
	#include "classfile/stringTable.hpp"
	#include "runtime/interfaceSupport.inline.hpp"
	#include "runtime/javaCalls.hpp"
	#include "runtime/serviceThread.hpp"
	#include "runtime/mutexLocker.hpp"
	#include "runtime/os.hpp"
	#include "prims/jvmtiImpl.hpp"
	#include "services/diagnosticArgument.hpp"
	#include "services/diagnosticFramework.hpp"
	#include "services/gcNotifier.hpp"
	#include "services/lowMemoryDetector.hpp"

	ServiceThread* ServiceThread::_instance = NULL;
	JvmtiDeferredEvent* ServiceThread::_jvmti_event = NULL;
	// The service thread has it's own static deferred event queue.
	// Events can be posted before JVMTI vm_start, so it's too early to call JvmtiThreadState::state_for
	// to add this field to the per-JavaThread event queue. TODO: fix this sometime later
	JvmtiDeferredEventQueue ServiceThread::_jvmti_service_queue;

	void ServiceThread::initialize() {
	EXCEPTION_MARK;

	const char* name = "Service Thread";
	Handle string = java_lang_String::create_from_str(name, CHECK);

	// Initialize thread_oop to put it into the system threadGroup
	Handle thread_group (THREAD, Universe::system_thread_group());
	Handle thread_oop = JavaCalls::construct_new_instance(
	SystemDictionary::Thread_klass(),
	vmSymbols::threadgroup_string_void_signature(),
	thread_group,
	string,
	CHECK);

	{
	MutexLocker mu(Threads_lock);
	ServiceThread* thread = new ServiceThread(&service_thread_entry);

	// At this point it may be possible that no osthread was created for the
	// JavaThread due to lack of memory. We would have to throw an exception
	// in that case. However, since this must work and we do not allow
	// exceptions anyway, check and abort if this fails.
	if (thread == NULL \|\| thread->osthread() == NULL) {
	vm_exit_during_initialization("java.lang.OutOfMemoryError",
	os::native_thread_creation_failed_msg());
	}

	java_lang_Thread::set_thread(thread_oop(), thread);
	java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
	java_lang_Thread::set_daemon(thread_oop());
	thread->set_threadObj(thread_oop());
	_instance = thread;

	Threads::add(thread);
	Thread::start(thread);
	}
	}

	void ServiceThread::service_thread_entry(JavaThread* jt, TRAPS) {
	while (true) {
	bool sensors_changed = false;
	bool has_jvmti_events = false;
	bool has_gc_notification_event = false;
	bool has_dcmd_notification_event = false;
	bool acs_notify = false;
	bool stringtable_work = false;
	JvmtiDeferredEvent jvmti_event;
	{
	// Need state transition ThreadBlockInVM so that this thread
	// will be handled by safepoint correctly when this thread is
	// notified at a safepoint.

	// This ThreadBlockInVM object is not also considered to be
	// suspend-equivalent because ServiceThread is not visible to
	// external suspension.

	ThreadBlockInVM tbivm(jt);

	MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
	while (!(sensors_changed = LowMemoryDetector::has_pending_requests()) &&
	!(has_jvmti_events = _jvmti_service_queue.has_events()) &&
	!(has_gc_notification_event = GCNotifier::has_event()) &&
	!(has_dcmd_notification_event = DCmdFactory::has_pending_jmx_notification()) &&
	!(stringtable_work = StringTable::has_work())) {
	// wait until one of the sensors has pending requests, or there is a
	// pending JVMTI event or JMX GC notification to post
	Service_lock->wait(Mutex::_no_safepoint_check_flag);
	}

	if (has_jvmti_events) {
	// Get the event under the Service_lock
	jvmti_event = _jvmti_service_queue.dequeue();
	_jvmti_event = &jvmti_event;
	}
	}

	if (stringtable_work) {
	StringTable::do_concurrent_work(jt);
	}

	if (has_jvmti_events) {
	_jvmti_event->post();
	_jvmti_event = NULL; // reset
	}

	if (sensors_changed) {
	LowMemoryDetector::process_sensor_changes(jt);
	}

	if(has_gc_notification_event) {
	GCNotifier::sendNotification(CHECK);
	}

	if(has_dcmd_notification_event) {
	DCmdFactory::send_notification(CHECK);
	}
	}
	}

	void ServiceThread::enqueue_deferred_event(JvmtiDeferredEvent* event) {
	MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
	// If you enqueue events before the service thread runs, gc and the sweeper
	// cannot keep the nmethod alive. This could be restricted to compiled method
	// load and unload events, if we wanted to be picky.
	assert(_instance != NULL, "cannot enqueue events before the service thread runs");
	_jvmti_service_queue.enqueue(*event);
	Service_lock->notify_all();
	}

	void ServiceThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
	JavaThread::oops_do(f, cf);
	// The ServiceThread "owns" the JVMTI Deferred events, scan them here
	// to keep them alive until they are processed.
	if (cf != NULL) {
	if (_jvmti_event != NULL) {
	_jvmti_event->oops_do(f, cf);
	}
	// Requires a lock, because threads can be adding to this queue.
	MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
	_jvmti_service_queue.oops_do(f, cf);
	}
	}

	void ServiceThread::nmethods_do(CodeBlobClosure* cf) {
	JavaThread::nmethods_do(cf);
	if (cf != NULL) {
	if (_jvmti_event != NULL) {
	_jvmti_event->nmethods_do(cf);
	}
	// Requires a lock, because threads can be adding to this queue.
	MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
	_jvmti_service_queue.nmethods_do(cf);
	}
	}