--- /dev/null 2015-10-28 10:02:44.098787667 +0100 +++ new/test/gc/g1/TestNoEagerReclaimOfHumongousRegions.java 2015-11-11 15:31:20.259910136 +0100 @@ -0,0 +1,91 @@ +/* + * Copyright (c) 2015, 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 TestNoEagerReclaimOfHumongousRegions + * @bug 8139424 + * @summary Test to check that a live humongous object is not eagerly reclaimed. This is a regression test for + * 8139424 and the test will crash if an eager reclaim occur. The test is not 100% deterministic and + * might pass even if there are problems in the code, but it will never crash unless there is a problem. + * @requires vm.gc=="G1" | vm.gc=="null" + * @key gc + * @library /testlibrary /test/lib + * @modules java.base/sun.misc + * @build TestNoEagerReclaimOfHumongousRegions + * @run main ClassFileInstaller sun.hotspot.WhiteBox + * sun.hotspot.WhiteBox$WhiteBoxPermission + * @run main/othervm -Xbootclasspath/a:. -XX:+PrintGC -XX:+UseG1GC -XX:MaxTenuringThreshold=0 -XX:G1RSetSparseRegionEntries=32 -XX:G1HeapRegionSize=1m -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -XX:+UnlockExperimentalVMOptions -XX:+G1TraceEagerReclaimHumongousObjects TestNoEagerReclaimOfHumongousRegions + */ + +import java.util.LinkedList; + +import sun.hotspot.WhiteBox; + +public class TestNoEagerReclaimOfHumongousRegions { + // Helper class to keep reference to humongous byte[]. + static class LargeRef { + private byte[] _ref; + + LargeRef(byte[] ref) { + _ref = ref; + } + + byte[] ref() { return _ref; } + } + + static LargeRef humongous_reference_holder; + + public static void main(String[] args) throws InterruptedException{ + WhiteBox wb = WhiteBox.getWhiteBox(); + LinkedList garbageAndRefList = new LinkedList(); + // Creating a 1M large byte array. Since the test specifies the heap + // region size to be 1m this will be a humongous object. We then + // store a pointer to the array in the static object to keep it live + // during the whole test. + humongous_reference_holder = new LargeRef(new byte[1 * 1024 * 1024]); + + // Create some garbage and a reference to the humongous object each round. + for (int i = 0; i < 32; i++) { + garbageAndRefList.add(new byte[400*1000]); + garbageAndRefList.add(new LargeRef(humongous_reference_holder.ref())); + + // Promote to old, goal is to get rem-set entries for the humongous + // object from different regions. The test specifies MaxTenuringThreshold=0, + // this will make sure we get objects promoted to old at once. + wb.youngGC(); + } + // Clear the garbage and reference list. + garbageAndRefList.clear(); + + // Run a concurrent mark cycle to mark all references but the static one as dead. + wb.g1StartConcMarkCycle(); + while (wb.g1InConcurrentMark()) { + Thread.sleep(100); + } + + // Run a young collection to make sure humongous object still can't be eagerly reclaimed. + wb.youngGC(); + // Will crash/assert if humongous object has been reclaimed. + wb.fullGC(); + } +}