/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.cassandra_voltpatches;
import java.lang.management.GarbageCollectorMXBean;
import java.lang.management.ManagementFactory;
import java.lang.management.MemoryMXBean;
import java.lang.management.MemoryUsage;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Random;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import javax.management.MBeanServer;
import javax.management.ObjectName;
import org.voltcore.logging.VoltLogger;
import com.google_voltpatches.common.collect.ImmutableSet;
public class GCInspector
{
private static final VoltLogger logger = new VoltLogger("GC");
final static long INTERVAL_IN_MS = 1000;
final static long MIN_DURATION = 200;
public static final GCInspector instance = new GCInspector();
private final HashMap<String, Long> gctimes = new HashMap<String, Long>();
private final HashMap<String, Long> gccounts = new HashMap<String, Long>();
final List<GarbageCollectorMXBean> beans = new ArrayList<GarbageCollectorMXBean>();
final MemoryMXBean membean = ManagementFactory.getMemoryMXBean();
public GCInspector()
{
MBeanServer server = ManagementFactory.getPlatformMBeanServer();
try
{
ObjectName gcName = new ObjectName(ManagementFactory.GARBAGE_COLLECTOR_MXBEAN_DOMAIN_TYPE + ",*");
for (ObjectName name : server.queryNames(gcName, null))
{
GarbageCollectorMXBean gc = ManagementFactory.newPlatformMXBeanProxy(server, name.getCanonicalName(), GarbageCollectorMXBean.class);
beans.add(gc);
}
}
catch (Exception e)
{
throw new RuntimeException(e);
}
}
public void start(ScheduledThreadPoolExecutor stpe)
{
// don't bother starting a thread that will do nothing.
if (beans.size() == 0)
return;
Runnable t = new Runnable()
{
@Override
public void run()
{
logGCResults();
}
};
stpe.scheduleAtFixedRate(t, INTERVAL_IN_MS, INTERVAL_IN_MS, TimeUnit.MILLISECONDS);
}
private static final ImmutableSet<String> oldGenGCs =
ImmutableSet.of(
"ConcurrentMarkSweep",
"PS MarkSweep",
"G1 Old Generation");
private void logGCResults()
{
for (GarbageCollectorMXBean gc : beans)
{
Long previousTotal = gctimes.get(gc.getName());
Long total = gc.getCollectionTime();
if (previousTotal == null)
previousTotal = 0L;
if (previousTotal.equals(total))
continue;
gctimes.put(gc.getName(), total);
Long duration = total - previousTotal; // may be zero for a really fast collection
Long previousCount = gccounts.get(gc.getName());
Long count = gc.getCollectionCount();
if (previousCount == null)
previousCount = 0L;
if (count.equals(previousCount))
continue;
gccounts.put(gc.getName(), count);
MemoryUsage mu = membean.getHeapMemoryUsage();
long memoryUsed = mu.getUsed();
long memoryMax = mu.getMax();
long durationPerCollection = duration / (count - previousCount);
if (durationPerCollection > MIN_DURATION) {
String st = String.format("GC for %s: %s ms for %s collections, %s used; max is %s",
gc.getName(), duration, count - previousCount, memoryUsed, memoryMax);
logger.info(st);
} else if (logger.isDebugEnabled()) {
String st = String.format("GC for %s: %s ms for %s collections, %s used; max is %s",
gc.getName(), duration, count - previousCount, memoryUsed, memoryMax);
logger.debug(st);
}
// if we just finished a full collection and we're still using a lot of memory, log
if (oldGenGCs.contains(gc.getName()))
{
double usage = (double) memoryUsed / memoryMax;
if (memoryUsed > .5 * memoryMax)
{
logger.warn("Heap is " + usage + " full out of " + memoryMax + ".");
}
}
}
}
public static void main(String args[]) throws Exception {
ArrayList<byte[]> stuff = new ArrayList<byte[]>();
GCInspector.instance.start(new ScheduledThreadPoolExecutor(1));
int allocations = 3000;
for (int ii = 0; ii < allocations; ii++) {
for (int zz = 0; zz < 1024; zz++) {
stuff.add(new byte[1024]);
}
}
Random r = new Random();
while (true) {
stuff.set(r.nextInt(stuff.size()), new byte[1024]);
}
}
}