| /* |
| * 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. |
| */ |
| |
| /* |
| * This file is available under and governed by the GNU General Public |
| * License version 2 only, as published by the Free Software Foundation. |
| * However, the following notice accompanied the original version of this |
| * file: |
| * |
| * Written by Doug Lea and Martin Buchholz with assistance from |
| * members of JCP JSR-166 Expert Group and released to the public |
| * domain, as explained at |
| * http://creativecommons.org/publicdomain/zero/1.0/ |
| */ |
| |
| /* |
| * @test |
| * @bug 8004138 |
| * @modules java.base/java.util.concurrent:open |
| * @summary Checks that ForkJoinTask thrown exceptions are not leaked. |
| * This whitebox test is sensitive to forkjoin implementation details. |
| */ |
| |
| import static java.util.concurrent.TimeUnit.SECONDS; |
| |
| import java.lang.ref.WeakReference; |
| import java.lang.reflect.Field; |
| import java.util.ArrayList; |
| import java.util.concurrent.CountDownLatch; |
| import java.util.concurrent.ForkJoinPool; |
| import java.util.concurrent.ForkJoinTask; |
| import java.util.concurrent.RecursiveAction; |
| import java.util.function.BooleanSupplier; |
| |
| public class FJExceptionTableLeak { |
| static class FailingTaskException extends RuntimeException {} |
| static class FailingTask extends RecursiveAction { |
| public void compute() { throw new FailingTaskException(); } |
| } |
| |
| static int bucketsInuse(Object[] exceptionTable) { |
| int count = 0; |
| for (Object x : exceptionTable) |
| if (x != null) count++; |
| return count; |
| } |
| |
| public static void main(String[] args) throws Exception { |
| final ForkJoinPool pool = new ForkJoinPool(4); |
| final Field exceptionTableField = |
| ForkJoinTask.class.getDeclaredField("exceptionTable"); |
| exceptionTableField.setAccessible(true); |
| final Object[] exceptionTable = (Object[]) exceptionTableField.get(null); |
| |
| if (bucketsInuse(exceptionTable) != 0) throw new AssertionError(); |
| |
| final ArrayList<FailingTask> tasks = new ArrayList<>(); |
| |
| // Keep submitting failing tasks until most of the exception |
| // table buckets are in use |
| do { |
| for (int i = 0; i < exceptionTable.length; i++) { |
| FailingTask task = new FailingTask(); |
| pool.execute(task); |
| tasks.add(task); // retain strong refs to all tasks, for now |
| } |
| for (FailingTask task : tasks) { |
| try { |
| task.join(); |
| throw new AssertionError("should throw"); |
| } catch (FailingTaskException success) {} |
| } |
| } while (bucketsInuse(exceptionTable) < exceptionTable.length * 3 / 4); |
| |
| // Retain a strong ref to one last failing task; |
| // task.join() will trigger exception table expunging. |
| FailingTask lastTask = tasks.get(0); |
| |
| // Clear all other strong refs, making exception table cleanable |
| tasks.clear(); |
| |
| BooleanSupplier exceptionTableIsClean = () -> { |
| try { |
| lastTask.join(); |
| throw new AssertionError("should throw"); |
| } catch (FailingTaskException expected) {} |
| int count = bucketsInuse(exceptionTable); |
| if (count == 0) |
| throw new AssertionError("expected to find last task"); |
| return count == 1; |
| }; |
| gcAwait(exceptionTableIsClean); |
| } |
| |
| // --------------- GC finalization infrastructure --------------- |
| |
| /** No guarantees, but effective in practice. */ |
| static void forceFullGc() { |
| CountDownLatch finalizeDone = new CountDownLatch(1); |
| WeakReference<?> ref = new WeakReference<Object>(new Object() { |
| protected void finalize() { finalizeDone.countDown(); }}); |
| try { |
| for (int i = 0; i < 10; i++) { |
| System.gc(); |
| if (finalizeDone.await(1L, SECONDS) && ref.get() == null) { |
| System.runFinalization(); // try to pick up stragglers |
| return; |
| } |
| } |
| } catch (InterruptedException unexpected) { |
| throw new AssertionError("unexpected InterruptedException"); |
| } |
| throw new AssertionError("failed to do a \"full\" gc"); |
| } |
| |
| static void gcAwait(BooleanSupplier s) { |
| for (int i = 0; i < 10; i++) { |
| if (s.getAsBoolean()) |
| return; |
| forceFullGc(); |
| } |
| throw new AssertionError("failed to satisfy condition"); |
| } |
| } |