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7129164: JNI Get/ReleasePrimitiveArrayCritical doesn't scale

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Reviewed-by: kvn, iveresov, dholmes
This commit is contained in:
Tom Rodriguez 2012-01-29 16:46:04 -08:00
parent e27deedf24
commit 5721fa222a
6 changed files with 182 additions and 81 deletions
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89
hotspot/src/share/vm/memory/gcLocker.cpp
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@ -1,5 +1,5 @@
/*
* Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1997, 2012, 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
@ -31,38 +31,93 @@ volatile jint GC_locker::_jni_lock_count = 0;
volatile jint GC_locker::_lock_count = 0;
volatile bool GC_locker::_needs_gc = false;
volatile bool GC_locker::_doing_gc = false;
jlong GC_locker::_wait_begin = 0;
#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", 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
_wait_begin = tty->time_stamp().milliseconds();
gclog_or_tty->print_cr(INT64_FORMAT ": Setting _needs_gc. Thread \"%s\" %d locked.",
_wait_begin, Thread::current()->name(), _jni_lock_count);
}
}
return is_active();
}
void GC_locker::stall_until_clear() {
assert(!JavaThread::current()->in_critical(), "Would deadlock");
if (PrintJNIGCStalls && PrintGCDetails) {
ResourceMark rm; // JavaThread::name() allocates to convert to UTF8
gclog_or_tty->print_cr(
"Allocation failed. Thread \"%s\" is stalled by JNI critical section.",
JavaThread::current()->name());
}
MutexLocker ml(JNICritical_lock);
if (needs_gc()) {
if (PrintJNIGCStalls && PrintGCDetails) {
ResourceMark rm; // JavaThread::name() allocates to convert to UTF8
gclog_or_tty->print_cr(INT64_FORMAT ": Allocation failed. Thread \"%s\" is stalled by JNI critical section, %d locked.",
tty->time_stamp().milliseconds() - _wait_begin, Thread::current()->name(), _jni_lock_count);
}
}
// Wait for _needs_gc to be cleared
while (GC_locker::needs_gc()) {
while (needs_gc()) {
JNICritical_lock->wait();
}
}
void GC_locker::jni_lock_slow() {
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_jni_active() && needs_gc()) || _doing_gc) {
while ((needs_gc() && is_jni_active()) || _doing_gc) {
JNICritical_lock->wait();
}
jni_lock();
thread->enter_critical();
_jni_lock_count++;
increment_debug_jni_lock_count();
}
void GC_locker::jni_unlock_slow() {
void GC_locker::jni_unlock(JavaThread* thread) {
assert(thread->in_last_critical(), "should be exiting critical region");
MutexLocker mu(JNICritical_lock);
jni_unlock();
_jni_lock_count--;
decrement_debug_jni_lock_count();
thread->exit_critical();
if (needs_gc() && !is_jni_active()) {
// We're the last thread out. Cause a GC to occur.
// GC will also check is_active, so this check is not
@ -74,11 +129,17 @@ void GC_locker::jni_unlock_slow() {
{
// 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(INT64_FORMAT ": Thread \"%s\" is performing GC after exiting critical section, %d locked",
tty->time_stamp().milliseconds() - _wait_begin, Thread::current()->name(), _jni_lock_count);
}
Universe::heap()->collect(GCCause::_gc_locker);
}
_doing_gc = false;
}
clear_needs_gc();
_needs_gc = false;
JNICritical_lock->notify_all();
}
}