Mercurial > hg > truffle
view src/share/vm/memory/gcLocker.cpp @ 20304:a22acf6d7598
8048112: G1 Full GC needs to support the case when the very first region is not available
Summary: Refactor preparation for compaction during Full GC so that it lazily initializes the first compaction point. This also avoids problems later when the first region may not be committed. Also reviewed by K. Barrett.
Reviewed-by: brutisso
author | tschatzl |
---|---|
date | Mon, 21 Jul 2014 10:00:31 +0200 |
parents | ce8f6bb717c9 |
children | 7848fc12602b |
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/* * 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