diff test/gc/g1/TestEagerReclaimHumongousRegions.java @ 20305:755930f931e3

8027959: Early reclamation of large objects in G1 Summary: Try to reclaim humongous objects at every young collection after doing a conservative estimate of its liveness. Reviewed-by: brutisso, mgerdin
author tschatzl
date Wed, 23 Jul 2014 09:03:32 +0200
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/gc/g1/TestEagerReclaimHumongousRegions.java	Wed Jul 23 09:03:32 2014 +0200
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+/*
+ * Copyright (c) 2014, 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 TestEagerReclaimHumongousRegions
+ * @bug 8027959
+ * @summary Test to make sure that eager reclaim of humongous objects work. We simply try to fill
+ * up the heap with humongous objects that should be eagerly reclaimable to avoid Full GC.
+ * @key gc
+ * @library /testlibrary
+ */
+
+import java.util.regex.Pattern;
+import java.util.regex.Matcher;
+import java.util.LinkedList;
+
+import com.oracle.java.testlibrary.OutputAnalyzer;
+import com.oracle.java.testlibrary.ProcessTools;
+import com.oracle.java.testlibrary.Asserts;
+
+class ReclaimRegionFast {
+    public static final int M = 1024*1024;
+
+    public static LinkedList<Object> garbageList = new LinkedList<Object>();
+
+    public static void genGarbage() {
+        for (int i = 0; i < 32*1024; i++) {
+            garbageList.add(new int[100]);
+        }
+        garbageList.clear();
+    }
+
+    // A large object referenced by a static.
+    static int[] filler = new int[10 * M];
+
+    public static void main(String[] args) {
+
+        int[] large = new int[M];
+
+        Object ref_from_stack = large;
+
+        for (int i = 0; i < 100; i++) {
+            // A large object that will be reclaimed eagerly.
+            large = new int[6*M];
+            genGarbage();
+            // Make sure that the compiler cannot completely remove
+            // the allocation of the large object until here.
+            System.out.println(large);
+        }
+
+        // Keep the reference to the first object alive.
+        System.out.println(ref_from_stack);
+    }
+}
+
+public class TestEagerReclaimHumongousRegions {
+    public static void main(String[] args) throws Exception {
+        ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
+            "-XX:+UseG1GC",
+            "-Xms128M",
+            "-Xmx128M",
+            "-Xmn16M",
+            "-XX:+PrintGC",
+            ReclaimRegionFast.class.getName());
+
+        Pattern p = Pattern.compile("Full GC");
+
+        OutputAnalyzer output = new OutputAnalyzer(pb.start());
+
+        int found = 0;
+        Matcher m = p.matcher(output.getStdout());
+        while (m.find()) { found++; }
+        System.out.println("Issued " + found + " Full GCs");
+        Asserts.assertLT(found, 10, "Found that " + found + " Full GCs were issued. This is larger than the bound. Eager reclaim seems to not work at all");
+
+        output.shouldHaveExitValue(0);
+    }
+}