1 /*

     2  * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 #include "precompiled.hpp"

    26 #include "classfile/systemDictionary.hpp"

    27 #include "gc/shared/concurrentGCThread.hpp"

    28 #include "oops/instanceRefKlass.hpp"

    29 #include "oops/oop.inline.hpp"

    30 #include "runtime/init.hpp"

    31 #include "runtime/interfaceSupport.hpp"

    32 #include "runtime/java.hpp"

    33 #include "runtime/javaCalls.hpp"

    34 #include "runtime/os.hpp"

    35 

    36 ConcurrentGCThread::ConcurrentGCThread() :

    37   _should_terminate(false), _has_terminated(false) {

    38 };

    39 

    40 void ConcurrentGCThread::create_and_start(ThreadPriority prio) {

    41   if (os::create_thread(this, os::cgc_thread)) {

    42     // XXX: need to set this to low priority

    43     // unless "aggressive mode" set; priority

    44     // should be just less than that of VMThread.

    45     os::set_priority(this, prio);

    46     if (!_should_terminate) {

    47       os::start_thread(this);

    48     }

    49   }

    50 }

    51 

    52 void ConcurrentGCThread::initialize_in_thread() {

    53   this->record_stack_base_and_size();

    54   this->initialize_named_thread();

    55   this->set_active_handles(JNIHandleBlock::allocate_block());

    56   // From this time Thread::current() should be working.

    57   assert(this == Thread::current(), "just checking");

    58 }

    59 

    60 void ConcurrentGCThread::wait_for_universe_init() {

    61   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);

    62   while (!is_init_completed() && !_should_terminate) {

    63     CGC_lock->wait(Mutex::_no_safepoint_check_flag, 1);

    64   }

    65 }

    66 

    67 void ConcurrentGCThread::terminate() {

    68   assert(_should_terminate, "Should only be called on terminate request.");

    69   // Signal that it is terminated

    70   {

    71     MutexLockerEx mu(Terminator_lock,

    72                      Mutex::_no_safepoint_check_flag);

    73     _has_terminated = true;

    74     Terminator_lock->notify();

    75   }

    76 }

    77 

    78 void ConcurrentGCThread::run() {

    79   initialize_in_thread();

    80   wait_for_universe_init();

    81 

    82   run_service();

    83 

    84   terminate();

    85 }

    86 

    87 void ConcurrentGCThread::stop() {

    88   // it is ok to take late safepoints here, if needed

    89   {

    90     MutexLockerEx mu(Terminator_lock);

    91     assert(!_has_terminated,   "stop should only be called once");

    92     assert(!_should_terminate, "stop should only be called once");

    93     _should_terminate = true;

    94   }

    95 

    96   stop_service();

    97 

    98   {

    99     MutexLockerEx mu(Terminator_lock);

   100     while (!_has_terminated) {

   101       Terminator_lock->wait();

   102     }

   103   }

   104 }