1.1 --- a/src/share/vm/memory/gcLocker.cpp Thu Jan 26 19:39:08 2012 -0800
1.2 +++ b/src/share/vm/memory/gcLocker.cpp Sun Jan 29 16:46:04 2012 -0800
1.3 @@ -1,5 +1,5 @@
1.4 /*
1.5 - * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
1.6 + * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
1.7 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.8 *
1.9 * This code is free software; you can redistribute it and/or modify it
1.10 @@ -31,38 +31,93 @@
1.11 volatile jint GC_locker::_lock_count = 0;
1.12 volatile bool GC_locker::_needs_gc = false;
1.13 volatile bool GC_locker::_doing_gc = false;
1.14 +jlong GC_locker::_wait_begin = 0;
1.15 +
1.16 +#ifdef ASSERT
1.17 +volatile jint GC_locker::_debug_jni_lock_count = 0;
1.18 +#endif
1.19 +
1.20 +
1.21 +#ifdef ASSERT
1.22 +void GC_locker::verify_critical_count() {
1.23 + if (SafepointSynchronize::is_at_safepoint()) {
1.24 + assert(!needs_gc() || _debug_jni_lock_count == _jni_lock_count, "must agree");
1.25 + int count = 0;
1.26 + // Count the number of threads with critical operations in progress
1.27 + for (JavaThread* thr = Threads::first(); thr; thr = thr->next()) {
1.28 + if (thr->in_critical()) {
1.29 + count++;
1.30 + }
1.31 + }
1.32 + if (_jni_lock_count != count) {
1.33 + tty->print_cr("critical counts don't match: %d != %d", _jni_lock_count, count);
1.34 + for (JavaThread* thr = Threads::first(); thr; thr = thr->next()) {
1.35 + if (thr->in_critical()) {
1.36 + tty->print_cr(INTPTR_FORMAT " in_critical %d", thr, thr->in_critical());
1.37 + }
1.38 + }
1.39 + }
1.40 + assert(_jni_lock_count == count, "must be equal");
1.41 + }
1.42 +}
1.43 +#endif
1.44 +
1.45 +bool GC_locker::check_active_before_gc() {
1.46 + assert(SafepointSynchronize::is_at_safepoint(), "only read at safepoint");
1.47 + if (is_active() && !_needs_gc) {
1.48 + verify_critical_count();
1.49 + _needs_gc = true;
1.50 + if (PrintJNIGCStalls && PrintGCDetails) {
1.51 + ResourceMark rm; // JavaThread::name() allocates to convert to UTF8
1.52 + _wait_begin = tty->time_stamp().milliseconds();
1.53 + gclog_or_tty->print_cr(INT64_FORMAT ": Setting _needs_gc. Thread \"%s\" %d locked.",
1.54 + _wait_begin, Thread::current()->name(), _jni_lock_count);
1.55 + }
1.56 +
1.57 + }
1.58 + return is_active();
1.59 +}
1.60
1.61 void GC_locker::stall_until_clear() {
1.62 assert(!JavaThread::current()->in_critical(), "Would deadlock");
1.63 - if (PrintJNIGCStalls && PrintGCDetails) {
1.64 - ResourceMark rm; // JavaThread::name() allocates to convert to UTF8
1.65 - gclog_or_tty->print_cr(
1.66 - "Allocation failed. Thread \"%s\" is stalled by JNI critical section.",
1.67 - JavaThread::current()->name());
1.68 + MutexLocker ml(JNICritical_lock);
1.69 +
1.70 + if (needs_gc()) {
1.71 + if (PrintJNIGCStalls && PrintGCDetails) {
1.72 + ResourceMark rm; // JavaThread::name() allocates to convert to UTF8
1.73 + gclog_or_tty->print_cr(INT64_FORMAT ": Allocation failed. Thread \"%s\" is stalled by JNI critical section, %d locked.",
1.74 + tty->time_stamp().milliseconds() - _wait_begin, Thread::current()->name(), _jni_lock_count);
1.75 + }
1.76 }
1.77 - MutexLocker ml(JNICritical_lock);
1.78 +
1.79 // Wait for _needs_gc to be cleared
1.80 - while (GC_locker::needs_gc()) {
1.81 + while (needs_gc()) {
1.82 JNICritical_lock->wait();
1.83 }
1.84 }
1.85
1.86 -void GC_locker::jni_lock_slow() {
1.87 +void GC_locker::jni_lock(JavaThread* thread) {
1.88 + assert(!thread->in_critical(), "shouldn't currently be in a critical region");
1.89 MutexLocker mu(JNICritical_lock);
1.90 // Block entering threads if we know at least one thread is in a
1.91 // JNI critical region and we need a GC.
1.92 // We check that at least one thread is in a critical region before
1.93 // blocking because blocked threads are woken up by a thread exiting
1.94 // a JNI critical region.
1.95 - while ((is_jni_active() && needs_gc()) || _doing_gc) {
1.96 + while ((needs_gc() && is_jni_active()) || _doing_gc) {
1.97 JNICritical_lock->wait();
1.98 }
1.99 - jni_lock();
1.100 + thread->enter_critical();
1.101 + _jni_lock_count++;
1.102 + increment_debug_jni_lock_count();
1.103 }
1.104
1.105 -void GC_locker::jni_unlock_slow() {
1.106 +void GC_locker::jni_unlock(JavaThread* thread) {
1.107 + assert(thread->in_last_critical(), "should be exiting critical region");
1.108 MutexLocker mu(JNICritical_lock);
1.109 - jni_unlock();
1.110 + _jni_lock_count--;
1.111 + decrement_debug_jni_lock_count();
1.112 + thread->exit_critical();
1.113 if (needs_gc() && !is_jni_active()) {
1.114 // We're the last thread out. Cause a GC to occur.
1.115 // GC will also check is_active, so this check is not
1.116 @@ -74,11 +129,17 @@
1.117 {
1.118 // Must give up the lock while at a safepoint
1.119 MutexUnlocker munlock(JNICritical_lock);
1.120 + if (PrintJNIGCStalls && PrintGCDetails) {
1.121 + ResourceMark rm; // JavaThread::name() allocates to convert to UTF8
1.122 + gclog_or_tty->print_cr(INT64_FORMAT ": Thread \"%s\" is performing GC after exiting critical section, %d locked",
1.123 + tty->time_stamp().milliseconds() - _wait_begin, Thread::current()->name(), _jni_lock_count);
1.124 + }
1.125 Universe::heap()->collect(GCCause::_gc_locker);
1.126 }
1.127 _doing_gc = false;
1.128 }
1.129 - clear_needs_gc();
1.130 +
1.131 + _needs_gc = false;
1.132 JNICritical_lock->notify_all();
1.133 }
1.134 }
