package org.apache.cassandra.service;
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*
* 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
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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.concurrent.TimeUnit;
import javax.management.MBeanServer;
import javax.management.ObjectName;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.config.DatabaseDescriptor;
import org.apache.cassandra.io.sstable.SSTableDeletingTask;
import org.apache.cassandra.utils.StatusLogger;
public class GCInspector
{
private static final Logger logger = LoggerFactory.getLogger(GCInspector.class);
final static long INTERVAL_IN_MS = 1000;
final static long MIN_DURATION = 200;
final static long MIN_DURATION_TPSTATS = 1000;
public static final GCInspector instance = new GCInspector();
private HashMap<String, Long> gctimes = new HashMap<String, Long>();
private HashMap<String, Long> gccounts = new HashMap<String, Long>();
List<GarbageCollectorMXBean> beans = new ArrayList<GarbageCollectorMXBean>();
MemoryMXBean membean = ManagementFactory.getMemoryMXBean();
private volatile boolean cacheSizesReduced;
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()
{
// don't bother starting a thread that will do nothing.
if (beans.size() == 0)
return;
Runnable t = new Runnable()
{
public void run()
{
logGCResults();
}
};
StorageService.scheduledTasks.scheduleWithFixedDelay(t, INTERVAL_IN_MS, INTERVAL_IN_MS, TimeUnit.MILLISECONDS);
}
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;
assert duration > 0;
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();
String st = String.format("GC for %s: %s ms for %s collections, %s used; max is %s",
gc.getName(), duration, count - previousCount, memoryUsed, memoryMax);
long durationPerCollection = duration / (count - previousCount);
if (durationPerCollection > MIN_DURATION)
logger.info(st);
else if (logger.isDebugEnabled())
logger.debug(st);
if (durationPerCollection > MIN_DURATION_TPSTATS)
StatusLogger.log();
// if we just finished a full collection and we're still using a lot of memory, try to reduce the pressure
if (gc.getName().equals("ConcurrentMarkSweep"))
{
SSTableDeletingTask.rescheduleFailedTasks();
double usage = (double) memoryUsed / memoryMax;
if (memoryUsed > DatabaseDescriptor.getReduceCacheSizesAt() * memoryMax && !cacheSizesReduced)
{
cacheSizesReduced = true;
logger.warn("Heap is " + usage + " full. You may need to reduce memtable and/or cache sizes. Cassandra is now reducing cache sizes to free up memory. Adjust reduce_cache_sizes_at threshold in cassandra.yaml if you don't want Cassandra to do this automatically");
StorageService.instance.reduceCacheSizes();
}
if (memoryUsed > DatabaseDescriptor.getFlushLargestMemtablesAt() * memoryMax)
{
logger.warn("Heap is " + usage + " full. You may need to reduce memtable and/or cache sizes. Cassandra will now flush up to the two largest memtables to free up memory. Adjust flush_largest_memtables_at threshold in cassandra.yaml if you don't want Cassandra to do this automatically");
StorageService.instance.flushLargestMemtables();
}
}
}
}
}