TestFullGCCount.java revision 4494
0N/A/*
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0N/A *
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0N/A * published by the Free Software Foundation.
0N/A *
0N/A * This code is distributed in the hope that it will be useful, but WITHOUT
0N/A * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
0N/A * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
0N/A * version 2 for more details (a copy is included in the LICENSE file that
0N/A * accompanied this code).
0N/A *
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0N/A * 2 along with this work; if not, write to the Free Software Foundation,
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0N/A *
1472N/A * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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0N/A */
0N/A
0N/A/*
0N/A * @test TestFullGCount.java
0N/A * @bug 7072527
0N/A * @summary CMS: JMM GC counters overcount in some cases
0N/A * @run main/othervm -XX:+PrintGC TestFullGCCount
0N/A */
0N/Aimport java.util.*;
0N/Aimport java.lang.management.*;
0N/A
0N/A/*
0N/A * Originally for a specific failure in CMS, this test now monitors all
0N/A * collectors for double-counting of collections.
0N/A */
0N/Apublic class TestFullGCCount {
0N/A
0N/A static List<GarbageCollectorMXBean> collectors = ManagementFactory.getGarbageCollectorMXBeans();
0N/A
0N/A public static void main(String[] args) {
0N/A int iterations = 20;
0N/A boolean failed = false;
0N/A String errorMessage = "";
0N/A HashMap<String, List> counts = new HashMap<String, List>();
2109N/A
0N/A // Prime the collection of count lists for all collectors.
0N/A for (int i = 0; i < collectors.size(); i++) {
0N/A GarbageCollectorMXBean collector = collectors.get(i);
0N/A counts.put(collector.getName(), new ArrayList<Long>(iterations));
0N/A }
0N/A
0N/A // Perform some gc, record collector counts.
0N/A for (int i = 0; i < iterations; i++) {
0N/A System.gc();
0N/A addCollectionCount(counts, i);
0N/A }
0N/A
0N/A // Check the increments:
0N/A // Old gen collectors should increase by one,
0N/A // New collectors may or may not increase.
0N/A // Any increase >=2 is unexpected.
0N/A for (String collector : counts.keySet()) {
0N/A System.out.println("Checking: " + collector);
0N/A
0N/A for (int i = 0; i < iterations - 1; i++) {
0N/A List<Long> theseCounts = counts.get(collector);
0N/A long a = theseCounts.get(i);
0N/A long b = theseCounts.get(i + 1);
0N/A if (b - a >= 2) {
0N/A failed = true;
0N/A errorMessage += "Collector '" + collector + "' has increment " + (b - a) +
0N/A " at iteration " + i + "\n";
0N/A }
0N/A }
0N/A }
2080N/A if (failed) {
0N/A System.err.println(errorMessage);
0N/A throw new RuntimeException("FAILED: System.gc collections miscounted.");
0N/A }
0N/A System.out.println("Passed.");
0N/A }
0N/A
0N/A private static void addCollectionCount(HashMap<String, List> counts, int iteration) {
0N/A for (int i = 0; i < collectors.size(); i++) {
0N/A GarbageCollectorMXBean collector = collectors.get(i);
0N/A List thisList = counts.get(collector.getName());
0N/A thisList.add(collector.getCollectionCount());
1010N/A }
1612N/A }
0N/A}
113N/A