jdk8-mips64-public/hotspot: src/share/vm/memory/gcLocker.cpp@7ae4e26cb1e0 (annotated)

src/share/vm/memory/gcLocker.cpp@7ae4e26cb1e0 (annotated)

src/share/vm/memory/gcLocker.cpp

Thu, 12 Oct 2017 21:27:07 +0800

author: aoqi
date: Thu, 12 Oct 2017 21:27:07 +0800
changeset 7535: 7ae4e26cb1e0
parent 6911: ce8f6bb717c9
parent 6876: 710a3c8b516e
child 9806: 758c07667682
permissions: -rw-r--r--

merge

 /*
  * Copyright (c) 1997, 2014, 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 "memory/gcLocker.inline.hpp"
 #include "memory/resourceArea.hpp"
 #include "memory/sharedHeap.hpp"
 #include "runtime/thread.inline.hpp"
 volatile jint GC_locker::_jni_lock_count = 0;
 volatile bool GC_locker::_needs_gc       = false;
 volatile bool GC_locker::_doing_gc       = false;
 #ifdef ASSERT
 volatile jint GC_locker::_debug_jni_lock_count = 0;
 #endif
 #ifdef ASSERT
 void GC_locker::verify_critical_count() {
   if (SafepointSynchronize::is_at_safepoint()) {
     assert(!needs_gc() || _debug_jni_lock_count == _jni_lock_count, "must agree");
     int count = 0;
     // Count the number of threads with critical operations in progress
     for (JavaThread* thr = Threads::first(); thr; thr = thr->next()) {
       if (thr->in_critical()) {
         count++;
       }
     }
     if (_jni_lock_count != count) {
       tty->print_cr("critical counts don't match: %d != %d", _jni_lock_count, count);
       for (JavaThread* thr = Threads::first(); thr; thr = thr->next()) {
         if (thr->in_critical()) {
           tty->print_cr(INTPTR_FORMAT " in_critical %d", p2i(thr), thr->in_critical());
         }
       }
     }
     assert(_jni_lock_count == count, "must be equal");
   }
 }
 #endif
 bool GC_locker::check_active_before_gc() {
   assert(SafepointSynchronize::is_at_safepoint(), "only read at safepoint");
   if (is_active() && !_needs_gc) {
     verify_critical_count();
     _needs_gc = true;
     if (PrintJNIGCStalls && PrintGCDetails) {
       ResourceMark rm; // JavaThread::name() allocates to convert to UTF8
       gclog_or_tty->print_cr("%.3f: Setting _needs_gc. Thread \"%s\" %d locked.",
                              gclog_or_tty->time_stamp().seconds(), Thread::current()->name(), _jni_lock_count);
     }
   }
   return is_active();
 }
 void GC_locker::stall_until_clear() {
   assert(!JavaThread::current()->in_critical(), "Would deadlock");
   MutexLocker   ml(JNICritical_lock);
   if (needs_gc()) {
     if (PrintJNIGCStalls && PrintGCDetails) {
       ResourceMark rm; // JavaThread::name() allocates to convert to UTF8
       gclog_or_tty->print_cr("%.3f: Allocation failed. Thread \"%s\" is stalled by JNI critical section, %d locked.",
                              gclog_or_tty->time_stamp().seconds(), Thread::current()->name(), _jni_lock_count);
     }
   }
   // Wait for _needs_gc  to be cleared
   while (needs_gc()) {
     JNICritical_lock->wait();
   }
 }
 void GC_locker::jni_lock(JavaThread* thread) {
   assert(!thread->in_critical(), "shouldn't currently be in a critical region");
   MutexLocker mu(JNICritical_lock);
   // Block entering threads if we know at least one thread is in a
   // JNI critical region and we need a GC.
   // We check that at least one thread is in a critical region before
   // blocking because blocked threads are woken up by a thread exiting
   // a JNI critical region.
   while (is_active_and_needs_gc() || _doing_gc) {
     JNICritical_lock->wait();
   }
   thread->enter_critical();
   _jni_lock_count++;
   increment_debug_jni_lock_count();
 }
 void GC_locker::jni_unlock(JavaThread* thread) {
   assert(thread->in_last_critical(), "should be exiting critical region");
   MutexLocker mu(JNICritical_lock);
   _jni_lock_count--;
   decrement_debug_jni_lock_count();
   thread->exit_critical();
   if (needs_gc() && !is_active_internal()) {
     // We're the last thread out. Cause a GC to occur.
     _doing_gc = true;
     {
       // Must give up the lock while at a safepoint
       MutexUnlocker munlock(JNICritical_lock);
       if (PrintJNIGCStalls && PrintGCDetails) {
         ResourceMark rm; // JavaThread::name() allocates to convert to UTF8
         gclog_or_tty->print_cr("%.3f: Thread \"%s\" is performing GC after exiting critical section, %d locked",
             gclog_or_tty->time_stamp().seconds(), Thread::current()->name(), _jni_lock_count);
       }
       Universe::heap()->collect(GCCause::_gc_locker);
     }
     _doing_gc = false;
     _needs_gc = false;
     JNICritical_lock->notify_all();
   }
 }
 // Implementation of No_GC_Verifier
 #ifdef ASSERT
 No_GC_Verifier::No_GC_Verifier(bool verifygc) {
   _verifygc = verifygc;
   if (_verifygc) {
     CollectedHeap* h = Universe::heap();
     assert(!h->is_gc_active(), "GC active during No_GC_Verifier");
     _old_invocations = h->total_collections();
   }
 }
 No_GC_Verifier::~No_GC_Verifier() {
   if (_verifygc) {
     CollectedHeap* h = Universe::heap();
     assert(!h->is_gc_active(), "GC active during No_GC_Verifier");
     if (_old_invocations != h->total_collections()) {
       fatal("collection in a No_GC_Verifier secured function");
     }
   }
 }
 Pause_No_GC_Verifier::Pause_No_GC_Verifier(No_GC_Verifier * ngcv) {
   _ngcv = ngcv;
   if (_ngcv->_verifygc) {
     // if we were verifying, then make sure that nothing is
     // wrong before we "pause" verification
     CollectedHeap* h = Universe::heap();
     assert(!h->is_gc_active(), "GC active during No_GC_Verifier");
     if (_ngcv->_old_invocations != h->total_collections()) {
       fatal("collection in a No_GC_Verifier secured function");
     }
   }
 }
 Pause_No_GC_Verifier::~Pause_No_GC_Verifier() {
   if (_ngcv->_verifygc) {
     // if we were verifying before, then reenable verification
     CollectedHeap* h = Universe::heap();
     assert(!h->is_gc_active(), "GC active during No_GC_Verifier");
     _ngcv->_old_invocations = h->total_collections();
   }
 }
 // JRT_LEAF rules:
 // A JRT_LEAF method may not interfere with safepointing by
 //   1) acquiring or blocking on a Mutex or JavaLock - checked
 //   2) allocating heap memory - checked
 //   3) executing a VM operation - checked
 //   4) executing a system call (including malloc) that could block or grab a lock
 //   5) invoking GC
 //   6) reaching a safepoint
 //   7) running too long
 // Nor may any method it calls.
 JRT_Leaf_Verifier::JRT_Leaf_Verifier()
   : No_Safepoint_Verifier(true, JRT_Leaf_Verifier::should_verify_GC())
 {
 }
 JRT_Leaf_Verifier::~JRT_Leaf_Verifier()
 {
 }
 bool JRT_Leaf_Verifier::should_verify_GC() {
   switch (JavaThread::current()->thread_state()) {
   case _thread_in_Java:
     // is in a leaf routine, there must be no safepoint.
     return true;
   case _thread_in_native:
     // A native thread is not subject to safepoints.
     // Even while it is in a leaf routine, GC is ok
     return false;
   default:
     // Leaf routines cannot be called from other contexts.
     ShouldNotReachHere();
     return false;
   }
 }
 #endif

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/memory/gcLocker.cpp@7ae4e26cb1e0 (annotated)

src/share/vm/memory/gcLocker.cpp