6711316: Open source the Garbage-First garbage collector

First mercurial integration of the code for the Garbage-First garbage collector.

Reviewed-by: apetrusenko, iveresov, jmasa, sgoldman, tonyp, ysr

hotspot/src/share/vm/gc_implementation/shared/concurrentGCThread.cpp

@@ -0,0 +1,314 @@
+/*
+ * Copyright 2001-2005 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+// CopyrightVersion 1.2
+
+# include "incls/_precompiled.incl"
+# include "incls/_concurrentGCThread.cpp.incl"
+
+bool ConcurrentGCThread::_should_terminate    = false;
+bool ConcurrentGCThread::_has_terminated      = false;
+int  ConcurrentGCThread::_CGC_flag            = CGC_nil;
+
+SuspendibleThreadSet ConcurrentGCThread::_sts;
+
+ConcurrentGCThread::ConcurrentGCThread() {
+  _sts.initialize();
+};
+
+void ConcurrentGCThread::stopWorldAndDo(VoidClosure* op) {
+  MutexLockerEx x(Heap_lock,
+                  Mutex::_no_safepoint_check_flag);
+  // warning("CGC: about to try stopping world");
+  SafepointSynchronize::begin();
+  // warning("CGC: successfully stopped world");
+  op->do_void();
+  SafepointSynchronize::end();
+  // warning("CGC: successfully restarted world");
+}
+
+void ConcurrentGCThread::safepoint_synchronize() {
+  _sts.suspend_all();
+}
+
+void ConcurrentGCThread::safepoint_desynchronize() {
+  _sts.resume_all();
+}
+
+void ConcurrentGCThread::create_and_start() {
+  if (os::create_thread(this, os::cgc_thread)) {
+    // XXX: need to set this to low priority
+    // unless "agressive mode" set; priority
+    // should be just less than that of VMThread.
+    os::set_priority(this, NearMaxPriority);
+    if (!_should_terminate && !DisableStartThread) {
+      os::start_thread(this);
+    }
+  }
+}
+
+void ConcurrentGCThread::initialize_in_thread() {
+  this->record_stack_base_and_size();
+  this->initialize_thread_local_storage();
+  this->set_active_handles(JNIHandleBlock::allocate_block());
+  // From this time Thread::current() should be working.
+  assert(this == Thread::current(), "just checking");
+}
+
+void ConcurrentGCThread::wait_for_universe_init() {
+  MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
+  while (!is_init_completed() && !_should_terminate) {
+    CGC_lock->wait(Mutex::_no_safepoint_check_flag, 200);
+  }
+}
+
+void ConcurrentGCThread::terminate() {
+  // Signal that it is terminated
+  {
+    MutexLockerEx mu(Terminator_lock,
+                     Mutex::_no_safepoint_check_flag);
+    _has_terminated = true;
+    Terminator_lock->notify();
+  }
+
+  // Thread destructor usually does this..
+  ThreadLocalStorage::set_thread(NULL);
+}
+
+
+void SuspendibleThreadSet::initialize_work() {
+  MutexLocker x(STS_init_lock);
+  if (!_initialized) {
+    _m             = new Monitor(Mutex::leaf,
+                                 "SuspendibleThreadSetLock", true);
+    _async         = 0;
+    _async_stop    = false;
+    _async_stopped = 0;
+    _initialized   = true;
+  }
+}
+
+void SuspendibleThreadSet::join() {
+  initialize();
+  MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
+  while (_async_stop) _m->wait(Mutex::_no_safepoint_check_flag);
+  _async++;
+  assert(_async > 0, "Huh.");
+}
+
+void SuspendibleThreadSet::leave() {
+  assert(_initialized, "Must be initialized.");
+  MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
+  _async--;
+  assert(_async >= 0, "Huh.");
+  if (_async_stop) _m->notify_all();
+}
+
+void SuspendibleThreadSet::yield(const char* id) {
+  assert(_initialized, "Must be initialized.");
+  if (_async_stop) {
+    MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
+    if (_async_stop) {
+      _async_stopped++;
+      assert(_async_stopped > 0, "Huh.");
+      if (_async_stopped == _async) {
+        if (ConcGCYieldTimeout > 0) {
+          double now = os::elapsedTime();
+          guarantee((now - _suspend_all_start) * 1000.0 <
+                    (double)ConcGCYieldTimeout,
+                    "Long delay; whodunit?");
+        }
+      }
+      _m->notify_all();
+      while (_async_stop) _m->wait(Mutex::_no_safepoint_check_flag);
+      _async_stopped--;
+      assert(_async >= 0, "Huh");
+      _m->notify_all();
+    }
+  }
+}
+
+void SuspendibleThreadSet::suspend_all() {
+  initialize();  // If necessary.
+  if (ConcGCYieldTimeout > 0) {
+    _suspend_all_start = os::elapsedTime();
+  }
+  MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
+  assert(!_async_stop, "Only one at a time.");
+  _async_stop = true;
+  while (_async_stopped < _async) _m->wait(Mutex::_no_safepoint_check_flag);
+}
+
+void SuspendibleThreadSet::resume_all() {
+  assert(_initialized, "Must be initialized.");
+  MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
+  assert(_async_stopped == _async, "Huh.");
+  _async_stop = false;
+  _m->notify_all();
+}
+
+static void _sltLoop(JavaThread* thread, TRAPS) {
+  SurrogateLockerThread* slt = (SurrogateLockerThread*)thread;
+  slt->loop();
+}
+
+SurrogateLockerThread::SurrogateLockerThread() :
+  JavaThread(&_sltLoop),
+  _monitor(Mutex::nonleaf, "SLTMonitor"),
+  _buffer(empty)
+{}
+
+SurrogateLockerThread* SurrogateLockerThread::make(TRAPS) {
+  klassOop k =
+    SystemDictionary::resolve_or_fail(vmSymbolHandles::java_lang_Thread(),
+                                      true, CHECK_NULL);
+  instanceKlassHandle klass (THREAD, k);
+  instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
+
+  const char thread_name[] = "Surrogate Locker Thread (CMS)";
+  Handle string = java_lang_String::create_from_str(thread_name, CHECK_NULL);
+
+  // Initialize thread_oop to put it into the system threadGroup
+  Handle thread_group (THREAD, Universe::system_thread_group());
+  JavaValue result(T_VOID);
+  JavaCalls::call_special(&result, thread_oop,
+                          klass,
+                          vmSymbolHandles::object_initializer_name(),
+                          vmSymbolHandles::threadgroup_string_void_signature(),
+                          thread_group,
+                          string,
+                          CHECK_NULL);
+
+  SurrogateLockerThread* res;
+  {
+    MutexLocker mu(Threads_lock);
+    res = new SurrogateLockerThread();
+
+    // 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 (res == NULL || res->osthread() == NULL) {
+      vm_exit_during_initialization("java.lang.OutOfMemoryError",
+                                    "unable to create new native thread");
+    }
+    java_lang_Thread::set_thread(thread_oop(), res);
+    java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
+    java_lang_Thread::set_daemon(thread_oop());
+
+    res->set_threadObj(thread_oop());
+    Threads::add(res);
+    Thread::start(res);
+  }
+  os::yield(); // This seems to help with initial start-up of SLT
+  return res;
+}
+
+void SurrogateLockerThread::manipulatePLL(SLT_msg_type msg) {
+  MutexLockerEx x(&_monitor, Mutex::_no_safepoint_check_flag);
+  assert(_buffer == empty, "Should be empty");
+  assert(msg != empty, "empty message");
+  _buffer = msg;
+  while (_buffer != empty) {
+    _monitor.notify();
+    _monitor.wait(Mutex::_no_safepoint_check_flag);
+  }
+}
+
+// ======= Surrogate Locker Thread =============
+
+void SurrogateLockerThread::loop() {
+  BasicLock pll_basic_lock;
+  SLT_msg_type msg;
+  debug_only(unsigned int owned = 0;)
+
+  while (/* !isTerminated() */ 1) {
+    {
+      MutexLocker x(&_monitor);
+      // Since we are a JavaThread, we can't be here at a safepoint.
+      assert(!SafepointSynchronize::is_at_safepoint(),
+             "SLT is a JavaThread");
+      // wait for msg buffer to become non-empty
+      while (_buffer == empty) {
+        _monitor.notify();
+        _monitor.wait();
+      }
+      msg = _buffer;
+    }
+    switch(msg) {
+      case acquirePLL: {
+        instanceRefKlass::acquire_pending_list_lock(&pll_basic_lock);
+        debug_only(owned++;)
+        break;
+      }
+      case releaseAndNotifyPLL: {
+        assert(owned > 0, "Don't have PLL");
+        instanceRefKlass::release_and_notify_pending_list_lock(&pll_basic_lock);
+        debug_only(owned--;)
+        break;
+      }
+      case empty:
+      default: {
+        guarantee(false,"Unexpected message in _buffer");
+        break;
+      }
+    }
+    {
+      MutexLocker x(&_monitor);
+      // Since we are a JavaThread, we can't be here at a safepoint.
+      assert(!SafepointSynchronize::is_at_safepoint(),
+             "SLT is a JavaThread");
+      _buffer = empty;
+      _monitor.notify();
+    }
+  }
+  assert(!_monitor.owned_by_self(), "Should unlock before exit.");
+}
+
+
+// ===== STS Access From Outside CGCT =====
+
+void ConcurrentGCThread::stsYield(const char* id) {
+  assert( Thread::current()->is_ConcurrentGC_thread(),
+          "only a conc GC thread can call this" );
+  _sts.yield(id);
+}
+
+bool ConcurrentGCThread::stsShouldYield() {
+  assert( Thread::current()->is_ConcurrentGC_thread(),
+          "only a conc GC thread can call this" );
+  return _sts.should_yield();
+}
+
+void ConcurrentGCThread::stsJoin() {
+  assert( Thread::current()->is_ConcurrentGC_thread(),
+          "only a conc GC thread can call this" );
+  _sts.join();
+}
+
+void ConcurrentGCThread::stsLeave() {
+  assert( Thread::current()->is_ConcurrentGC_thread(),
+          "only a conc GC thread can call this" );
+  _sts.leave();
+}