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/*
* Copyright (c) 2013, 2024, 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.
*/
import java.util.concurrent.TimeUnit;
import java.util.concurrent.Phaser;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;
import java.util.function.Consumer;
import java.util.stream.IntStream;
import java.util.stream.Stream;
/**
* @test
* @bug 8066859
* @summary Check that AQS-based locks, conditions, and CountDownLatches do not fail when encountering OOME
* @requires vm.gc.G1
* @run main/othervm -XX:+UseG1GC -XX:-UseGCOverheadLimit -Xmx48M -XX:-UseTLAB OOMEInAQS
*/
public class OOMEInAQS extends Thread {
static final int NTHREADS = 2; // intentionally not a scalable test; > 2 is very slow
static final int NREPS = 100;
// statically allocate
static final ReentrantLock mainLock = new ReentrantLock();
static final Condition condition = mainLock.newCondition();
static final CountDownLatch started = new CountDownLatch(1);
static final CountDownLatch filled = new CountDownLatch(1);
static final CountDownLatch canFill = new CountDownLatch(NTHREADS);
static volatile Object data;
static volatile Throwable exception;
static int turn;
/**
* For each of NTHREADS threads, REPS times: Take turns
* executing. Introduce OOM using fillHeap during runs. In
* addition to testing AQS, the CountDownLatches ensure that
* methods execute at least once before OutOfMemory occurs, to
* avoid uncontrollable impact of OOME during class-loading.
*/
public static void main(String[] args) throws Throwable {
OOMEInAQS[] threads = new OOMEInAQS[NTHREADS];
for (int i = 0; i < NTHREADS; ++i)
(threads[i] = new OOMEInAQS(i)).start();
started.countDown();
canFill.await();
long t0 = System.nanoTime();
data = fillHeap();
filled.countDown();
long t1 = System.nanoTime();
for (int i = 0; i < NTHREADS; ++i)
threads[i].join();
data = null; // free heap before reporting and terminating
System.gc();
Throwable ex = exception;
if (ex != null)
throw ex;
System.out.println(
"fillHeap time: " + (t1 - t0) / 1000_000 +
" millis, whole test time: " + (System.nanoTime() - t0) / 1000_000 +
" millis"
);
}
final int tid;
OOMEInAQS(int tid) {
this.tid = tid;
}
@Override
public void run() {
int id = tid, nextId = (id + 1) % NTHREADS;
final ReentrantLock lock = mainLock;
final Condition cond = condition;
try {
started.await();
for (int i = 0; i < NREPS; i++) {
lock.lock();
try {
while (turn != id)
cond.await();
turn = nextId;
cond.signalAll();
} finally {
lock.unlock();
}
if (i == 2) { // Subsequent AQS methods encounter OOME
canFill.countDown();
filled.await();
}
}
data = null;
System.gc(); // avoid getting stuck while exiting
} catch (Throwable ex) {
data = null;
System.gc(); // avoid nested OOME
exception = ex;
}
}
static Object[] fillHeap() {
Object[] first = null, last = null;
int size = 1 << 20;
while (size > 0) {
try {
Object[] array = new Object[size];
if (first == null) {
first = array;
} else {
last[0] = array;
}
last = array;
} catch (OutOfMemoryError oome) {
size = size >>> 1;
}
}
return first;
}
}
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