7072527: CMS: JMM GC counters overcount in some cases

Summary: Avoid overcounting when CMS has concurrent mode failure.
Reviewed-by: ysr
Contributed-by: rednaxelafx@gmail.com

src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp

@@ -2025,9 +2025,6 @@ void CMSCollector::do_compaction_work(bool clear_all_soft_refs) {
                                             _intra_sweep_estimate.padded_average());
   }
 
-  {
-    TraceCMSMemoryManagerStats tmms(gch->gc_cause());
-  }
   GenMarkSweep::invoke_at_safepoint(_cmsGen->level(),
     ref_processor(), clear_all_soft_refs);
   #ifdef ASSERT
@@ -9345,15 +9342,3 @@ TraceCMSMemoryManagerStats::TraceCMSMemoryManagerStats(CMSCollector::CollectorSt
   }
 }
 
-// when bailing out of cms in concurrent mode failure
-TraceCMSMemoryManagerStats::TraceCMSMemoryManagerStats(GCCause::Cause cause): TraceMemoryManagerStats() {
-  initialize(true /* fullGC */ ,
-             cause /* cause of the GC */,
-             true /* recordGCBeginTime */,
-             true /* recordPreGCUsage */,
-             true /* recordPeakUsage */,
-             true /* recordPostGCusage */,
-             true /* recordAccumulatedGCTime */,
-             true /* recordGCEndTime */,
-             true /* countCollection */ );
-}

src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp

@@ -1900,7 +1900,6 @@ class TraceCMSMemoryManagerStats : public TraceMemoryManagerStats {
 
  public:
   TraceCMSMemoryManagerStats(CMSCollector::CollectorState phase, GCCause::Cause cause);
-  TraceCMSMemoryManagerStats(GCCause::Cause cause);
 };
 
 

test/gc/7072527/TestFullGCCount.java

+/*
+ * Copyright (c) 2011, 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 TestFullGCount.java
+ * @bug 7072527
+ * @summary CMS: JMM GC counters overcount in some cases
+ * @run main/othervm -XX:+UseConcMarkSweepGC TestFullGCCount
+ *
+ */
+import java.util.*;
+import java.lang.management.*;
+
+public class TestFullGCCount {
+
+    public String collectorName = "ConcurrentMarkSweep";
+
+    public static void main(String [] args) {
+
+        TestFullGCCount t = null;
+        if (args.length==2) {
+            t = new TestFullGCCount(args[0], args[1]);
+        } else {
+            t = new TestFullGCCount();
+        }
+        System.out.println("Monitoring collector: " + t.collectorName);
+        t.run();
+    }
+
+    public TestFullGCCount(String pool, String collector) {
+        collectorName = collector;
+    }
+
+    public TestFullGCCount() {
+    }
+
+    public void run() {
+        int count = 0;
+        int iterations = 20;
+        long counts[] = new long[iterations];
+        boolean diffAlways2 = true; // assume we will fail
+
+        for (int i=0; i<iterations; i++) {
+            System.gc();
+            counts[i] = getCollectionCount();
+            if (i>0) {
+                if (counts[i] - counts[i-1] != 2) {
+                    diffAlways2 = false;
+                }
+            }
+        }
+        if (diffAlways2) {
+            throw new RuntimeException("FAILED: System.gc must be incrementing count twice.");
+        }
+        System.out.println("Passed.");
+    }
+
+    private long getCollectionCount() {
+        long count = 0;
+        List<MemoryPoolMXBean> pools = ManagementFactory.getMemoryPoolMXBeans();
+        List<GarbageCollectorMXBean> collectors = ManagementFactory.getGarbageCollectorMXBeans();
+        for (int i=0; i<collectors.size(); i++) {
+            GarbageCollectorMXBean collector = collectors.get(i);
+            String name = collector.getName();
+            if (name.contains(collectorName)) {
+                System.out.println(name + ": collection count = "
+                                   + collector.getCollectionCount());
+                count = collector.getCollectionCount();
+            }
+        }
+        return count;
+    }
+
+}
+