Bug 1190301 - EAP 6 plug-in will exhaust JVM heap when Maximum reques…

…t time _internal:maxTime) measurement is disabled

Replaced maxTime implementation based on ArrayList by an implementation based on AtomicLong.

modules/plugins/jboss-as-7/src/main/java/org/rhq/modules/plugins/jbossas7/PluginStats.java

@@ -1,22 +1,37 @@
+/*
+ * RHQ Management Platform
+ * Copyright (C) 2005-2014 Red Hat, Inc.
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation version 2 of the License.
+ *
+ * This program 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 for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
 package org.rhq.modules.plugins.jbossas7;
 
-import java.util.ArrayList;
-import java.util.List;
 import java.util.concurrent.atomic.AtomicLong;
 
 /**
- * Singleton that keeps track of some statistics of this plugin
+ * Singleton that keeps track of some statistics of this plugin.
+ *
  * @author Heiko W. Rupp
  */
 public class PluginStats {
     private static PluginStats ourInstance = new PluginStats();
 
     AtomicLong requestCount = new AtomicLong();
     AtomicLong requestTime = new AtomicLong();
-    private static final int FIFO_SIZE = 200; // Initial capacity
-    List<Long> maxTime = new ArrayList<Long>(FIFO_SIZE);
-    final Object lock = new Object();
-
+    AtomicLong maxTime = new AtomicLong();
 
     public static PluginStats getInstance() {
         return ourInstance;
@@ -29,9 +44,12 @@ public void incrementRequestCount() {
         requestCount.incrementAndGet();
     }
 
-    public void addRequestTime(long l) {
-        requestTime.addAndGet(l);
-        insertTime(l);
+    public void addRequestTime(long time) {
+        requestTime.addAndGet(time);
+        long currentMax;
+        do {
+            currentMax = maxTime.get();
+        } while (currentMax < time && !maxTime.compareAndSet(currentMax, time));
     }
 
     public long getRequestCount() {
@@ -43,19 +61,6 @@ public long getRequestTime() {
     }
 
     public long getMaxTime() {
-        long max = 0;
-        synchronized (lock) {
-            for (Long i : maxTime)
-                if (i > max )
-                    max = i;
-            maxTime = new ArrayList<Long>();
-        }
-        return max;
-    }
-
-    private void insertTime(long time) {
-        synchronized (lock) {
-            maxTime.add(time);
-        }
+        return maxTime.getAndSet(0);
     }
 }

modules/plugins/jboss-as-7/src/test/java/org/rhq/modules/plugins/jbossas7/PluginStatsTest.java

@@ -0,0 +1,98 @@
+/*
+ * RHQ Management Platform
+ * Copyright (C) 2005-2014 Red Hat, Inc.
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation version 2 of the License.
+ *
+ * This program 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 for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+package org.rhq.modules.plugins.jbossas7;
+
+import static org.testng.Assert.assertEquals;
+
+import java.lang.reflect.Constructor;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Random;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+
+import org.testng.annotations.AfterTest;
+import org.testng.annotations.BeforeTest;
+import org.testng.annotations.Test;
+
+/**
+ * @author Thomas Segismont
+ */
+@Test(timeOut = 5 * 60 * 1000)
+public class PluginStatsTest {
+
+    private PluginStats pluginStats;
+    private ExecutorService executorService;
+    private int generatorLoop;
+
+    @BeforeTest
+    public void setup() throws Exception {
+        Constructor<PluginStats> constructor = PluginStats.class.getDeclaredConstructor();
+        constructor.setAccessible(true);
+        pluginStats = constructor.newInstance();
+        executorService = Executors.newCachedThreadPool();
+        generatorLoop = 3 * 1000 * 1000; // 3 million loops
+    }
+
+    @Test
+    public void testMaxRequestTime() throws Exception {
+        List<Callable<Long>> generators = new ArrayList<Callable<Long>>();
+        for (int i = 0; i < 4; i++) {
+            generators.add(newRequestTimeGenerator());
+        }
+        List<Future<Long>> maxByGeneratorFutures = executorService.invokeAll(generators);
+        List<Long> maxByGenerators = new ArrayList<Long>();
+        for (Future<Long> maxByGeneratorFuture : maxByGeneratorFutures) {
+            maxByGenerators.add(maxByGeneratorFuture.get(5, TimeUnit.MINUTES));
+        }
+        Collections.sort(maxByGenerators, Collections.reverseOrder());
+        Long expectedMaxTime = maxByGenerators.get(0);
+        assertEquals(expectedMaxTime, Long.valueOf(pluginStats.getMaxTime()), maxByGenerators.toString());
+        assertEquals(0, pluginStats.getMaxTime(), "max time stat should have been reset to 0");
+    }
+
+    private Callable<Long> newRequestTimeGenerator() {
+        return new Callable<Long>() {
+            @Override
+            public Long call() throws Exception {
+                long max = 0;
+                Random random = new Random();
+                for (int i = 0; i < generatorLoop; i++) {
+                    long time = Math.abs(random.nextInt());
+                    if (max < time) {
+                        max = time;
+                    }
+                    pluginStats.addRequestTime(time);
+                }
+                return max;
+            }
+        };
+    }
+
+    @AfterTest
+    public void tearDown() {
+        executorService.shutdown();
+    }
+
+}