--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/test/hotspot/jtreg/gc/g1/TestGreyReclaimedHumongousObjects.java Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,176 @@
+/*
+ * Copyright (c) 2015, 2016, 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.
+ */
+
+/*
+ * @test TestGreyReclaimedHumongousObjects.java
+ * @bug 8069367
+ * @requires vm.gc.G1
+ * @summary Test handling of marked but unscanned reclaimed humongous objects.
+ * @key gc
+ * @modules jdk.management
+ * @run main/othervm -XX:+UseG1GC -Xss32m -Xmx128m -XX:G1HeapRegionSize=1m
+ * -XX:+UnlockExperimentalVMOptions
+ * -XX:+G1EagerReclaimHumongousObjects
+ * -XX:+G1EagerReclaimHumongousObjectsWithStaleRefs
+ * TestGreyReclaimedHumongousObjects 1048576 90
+ */
+
+// This test spawns a bunch of threads, each of them rapidly
+// allocating large objects and storing them into a circular buffer
+// associated with the thread. The circular buffer results in these
+// objects becoming dead in fairly short order.
+//
+// The situation we're trying to provoke is
+//
+// (1) A humongous object H is marked and added to the mark stack.
+//
+// (2) An evacuation pause determines H is no longer live, and
+// reclaims it. This occurs before concurrent marking has gotten
+// around to processing the mark stack entry for H.
+//
+// (3) Concurrent marking processes the mark stack entry for H. The
+// bug is that it would attempt to scan the now dead object.
+//
+// Unfortunately, this test is *very* sensitive to configuration.
+// Among the parameters that affect whether / how often we'll get into
+// the desired situation within a reasonable amount of time are:
+//
+// - THREAD_COUNT: The number of allocating threads.
+//
+// - OLD_COUNT: The number of objects each thread keeps.
+//
+// - MAX_MEMORY: The maximum heap size.
+//
+// - G1HeapRegionSize
+//
+// - The size of the objects being allocated.
+//
+// The parameter values specified here:
+//
+// - THREAD_COUNT = 12
+// - OLD_COUNT == 4
+// - MAX_MEMORY == 128m
+// - G1HeapRegionSize = 1m
+// - Object size = 1048576 (2 regions after header overhead and roundup)
+//
+// seems to work well at provoking the desired state fairly quickly.
+// Even relatively small perturbations may change that. The key
+// factors seem to be keeping the heap mostly full of live objects but
+// having them become dead fairly quickly.
+
+import java.util.Date;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.TimeUnit;
+import com.sun.management.HotSpotDiagnosticMXBean;
+import java.lang.management.ManagementFactory;
+
+public class TestGreyReclaimedHumongousObjects {
+
+ static class NamedThreadFactory implements ThreadFactory {
+ private int threadNum = 0;
+
+ @Override
+ public Thread newThread(Runnable r) {
+ return new Thread(r, THREAD_NAME + (threadNum++));
+ }
+ }
+
+ static class Runner extends Thread {
+ private final Date startDate = new Date();
+ private final int obj_size;
+ private final Object[] old_garbage;
+ private int old_index = 0;
+
+ public Runner(int obj_size) {
+ this.obj_size = obj_size;
+ old_garbage = new Object[OLD_COUNT];
+ }
+
+ private void allocate_garbage() {
+ byte[] garbage = new byte[obj_size];
+ old_garbage[Math.abs(++old_index % OLD_COUNT)] = garbage;
+ }
+
+ @Override
+ public void run() {
+ try {
+ while (!isInterrupted()) {
+ allocate_garbage();
+ Thread.sleep(0); // Yield, to ensure interruptable.
+ }
+ } catch (InterruptedException e) {
+ System.out.println("Aborted after "
+ + (new Date().getTime() - startDate.getTime())
+ + " ms");
+ interrupt();
+ }
+ }
+ }
+
+ public static void main(String[] args) throws Exception {
+ HotSpotDiagnosticMXBean diagnostic =
+ ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class);
+
+ System.out.println("Max memory= " + MAX_MEMORY + " bytes");
+
+ int obj_size = 0;
+ long seconds_to_run = 0;
+ if (args.length != 2) {
+ throw new RuntimeException("Object size argument must be supplied");
+ } else {
+ obj_size = Integer.parseInt(args[0]);
+ seconds_to_run = Integer.parseInt(args[1]);
+ }
+ System.out.println("Objects size= " + obj_size + " bytes");
+ System.out.println("Seconds to run=" + seconds_to_run);
+
+ int region_size =
+ Integer.parseInt(diagnostic.getVMOption("G1HeapRegionSize").getValue());
+ if (obj_size < (region_size / 2)) {
+ throw new RuntimeException("Object size " + obj_size +
+ " is not humongous with region size " + region_size);
+ }
+
+ ExecutorService executor =
+ Executors.newFixedThreadPool(THREAD_COUNT, new NamedThreadFactory());
+ System.out.println("Starting " + THREAD_COUNT + " threads");
+
+ for (int i = 0; i < THREAD_COUNT; i++) {
+ executor.execute(new Runner(obj_size));
+ }
+
+ Thread.sleep(seconds_to_run * 1000);
+ executor.shutdownNow();
+
+ if (!executor.awaitTermination(10, TimeUnit.SECONDS)) {
+ System.err.println("Thread pool did not terminate after 10 seconds after shutdown");
+ }
+ }
+
+ private static final long MAX_MEMORY = Runtime.getRuntime().maxMemory();
+ private static final int OLD_COUNT = 4;
+ private static final int THREAD_COUNT = 12;
+ private static final String THREAD_NAME = "TestGreyRH-";
+}