--- old/src/share/vm/memory/gcLocker.cpp 2015-05-13 13:58:16.579676261 +0200 +++ /dev/null 2015-03-18 17:10:38.111854831 +0100 @@ -1,232 +0,0 @@ -/* - * 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 "gc_interface/collectedHeap.hpp" -#include "memory/gcLocker.inline.hpp" -#include "memory/resourceArea.hpp" -#include "runtime/atomic.inline.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"); - } -} - -// In debug mode track the locking state at all times -void GC_locker::increment_debug_jni_lock_count() { - assert(_debug_jni_lock_count >= 0, "bad value"); - Atomic::inc(&_debug_jni_lock_count); -} - -void GC_locker::decrement_debug_jni_lock_count() { - assert(_debug_jni_lock_count > 0, "bad value"); - Atomic::dec(&_debug_jni_lock_count); -} -#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 --- /dev/null 2015-03-18 17:10:38.111854831 +0100 +++ new/src/share/vm/gc/shared/gcLocker.cpp 2015-05-13 13:58:16.389668367 +0200 @@ -0,0 +1,232 @@ +/* + * Copyright (c) 1997, 2015, 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 "gc/shared/collectedHeap.hpp" +#include "gc/shared/gcLocker.inline.hpp" +#include "memory/resourceArea.hpp" +#include "runtime/atomic.inline.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"); + } +} + +// In debug mode track the locking state at all times +void GC_locker::increment_debug_jni_lock_count() { + assert(_debug_jni_lock_count >= 0, "bad value"); + Atomic::inc(&_debug_jni_lock_count); +} + +void GC_locker::decrement_debug_jni_lock_count() { + assert(_debug_jni_lock_count > 0, "bad value"); + Atomic::dec(&_debug_jni_lock_count); +} +#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