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Main functionality for HBase
/**
* Copyright The Apache Software Foundation
*
* 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.hadoop.hbase.regionserver;
import java.lang.management.MemoryUsage;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.Executors;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.io.util.HeapMemorySizeUtil;
import org.apache.hadoop.hbase.regionserver.HeapMemStoreLAB.Chunk;
import org.apache.hadoop.util.StringUtils;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
/**
* A pool of {@link HeapMemStoreLAB.Chunk} instances.
*
* MemStoreChunkPool caches a number of retired chunks for reusing, it could
* decrease allocating bytes when writing, thereby optimizing the garbage
* collection on JVM.
*
* The pool instance is globally unique and could be obtained through
* {@link MemStoreChunkPool#getPool(Configuration)}
*
* {@link MemStoreChunkPool#getChunk()} is called when MemStoreLAB allocating
* bytes, and {@link MemStoreChunkPool#putbackChunks(BlockingQueue)} is called
* when MemStore clearing snapshot for flush
*/
@SuppressWarnings("javadoc")
@InterfaceAudience.Private
public class MemStoreChunkPool {
private static final Log LOG = LogFactory.getLog(MemStoreChunkPool.class);
final static String CHUNK_POOL_MAXSIZE_KEY = "hbase.hregion.memstore.chunkpool.maxsize";
final static String CHUNK_POOL_INITIALSIZE_KEY = "hbase.hregion.memstore.chunkpool.initialsize";
final static float POOL_MAX_SIZE_DEFAULT = 0.0f;
final static float POOL_INITIAL_SIZE_DEFAULT = 0.0f;
// Static reference to the MemStoreChunkPool
private static MemStoreChunkPool GLOBAL_INSTANCE;
/** Boolean whether we have disabled the memstore chunk pool entirely. */
static boolean chunkPoolDisabled = false;
private final int maxCount;
// A queue of reclaimed chunks
private final BlockingQueue reclaimedChunks;
private final int chunkSize;
/** Statistics thread schedule pool */
private final ScheduledExecutorService scheduleThreadPool;
/** Statistics thread */
private static final int statThreadPeriod = 60 * 5;
private AtomicLong createdChunkCount = new AtomicLong();
private AtomicLong reusedChunkCount = new AtomicLong();
MemStoreChunkPool(Configuration conf, int chunkSize, int maxCount,
int initialCount) {
this.maxCount = maxCount;
this.chunkSize = chunkSize;
this.reclaimedChunks = new LinkedBlockingQueue();
for (int i = 0; i < initialCount; i++) {
Chunk chunk = new Chunk(chunkSize);
chunk.init();
reclaimedChunks.add(chunk);
}
final String n = Thread.currentThread().getName();
scheduleThreadPool = Executors.newScheduledThreadPool(1,
new ThreadFactoryBuilder().setNameFormat(n+"-MemStoreChunkPool Statistics")
.setDaemon(true).build());
this.scheduleThreadPool.scheduleAtFixedRate(new StatisticsThread(this),
statThreadPeriod, statThreadPeriod, TimeUnit.SECONDS);
}
/**
* Poll a chunk from the pool, reset it if not null, else create a new chunk
* to return
* @return a chunk
*/
Chunk getChunk() {
Chunk chunk = reclaimedChunks.poll();
if (chunk == null) {
chunk = new Chunk(chunkSize);
createdChunkCount.incrementAndGet();
} else {
chunk.reset();
reusedChunkCount.incrementAndGet();
}
return chunk;
}
/**
* Add the chunks to the pool, when the pool achieves the max size, it will
* skip the remaining chunks
* @param chunks
*/
void putbackChunks(BlockingQueue chunks) {
int maxNumToPutback = this.maxCount - reclaimedChunks.size();
if (maxNumToPutback <= 0) {
return;
}
chunks.drainTo(reclaimedChunks, maxNumToPutback);
// clear reference of any non-reclaimable chunks
if (chunks.size() > 0) {
if (LOG.isTraceEnabled()) {
LOG.trace("Left " + chunks.size() + " unreclaimable chunks, removing them from queue");
}
chunks.clear();
}
}
/**
* Add the chunk to the pool, if the pool has achieved the max size, it will
* skip it
* @param chunk
*/
void putbackChunk(Chunk chunk) {
if (reclaimedChunks.size() >= this.maxCount) {
return;
}
reclaimedChunks.add(chunk);
}
int getPoolSize() {
return this.reclaimedChunks.size();
}
/*
* Only used in testing
*/
void clearChunks() {
this.reclaimedChunks.clear();
}
private static class StatisticsThread extends Thread {
MemStoreChunkPool mcp;
public StatisticsThread(MemStoreChunkPool mcp) {
super("MemStoreChunkPool.StatisticsThread");
setDaemon(true);
this.mcp = mcp;
}
@Override
public void run() {
mcp.logStats();
}
}
private void logStats() {
if (!LOG.isDebugEnabled()) return;
long created = createdChunkCount.get();
long reused = reusedChunkCount.get();
long total = created + reused;
LOG.debug("Stats: current pool size=" + reclaimedChunks.size()
+ ",created chunk count=" + created
+ ",reused chunk count=" + reused
+ ",reuseRatio=" + (total == 0 ? "0" : StringUtils.formatPercent(
(float) reused / (float) total, 2)));
}
/**
* @param conf
* @return the global MemStoreChunkPool instance
*/
@edu.umd.cs.findbugs.annotations.SuppressWarnings(value="DC_DOUBLECHECK",
justification="Intentional")
static MemStoreChunkPool getPool(Configuration conf) {
if (GLOBAL_INSTANCE != null) return GLOBAL_INSTANCE;
synchronized (MemStoreChunkPool.class) {
if (chunkPoolDisabled) return null;
if (GLOBAL_INSTANCE != null) return GLOBAL_INSTANCE;
float poolSizePercentage = conf.getFloat(CHUNK_POOL_MAXSIZE_KEY, POOL_MAX_SIZE_DEFAULT);
if (poolSizePercentage <= 0) {
chunkPoolDisabled = true;
return null;
}
if (poolSizePercentage > 1.0) {
throw new IllegalArgumentException(CHUNK_POOL_MAXSIZE_KEY + " must be between 0.0 and 1.0");
}
long heapMax = -1L;
final MemoryUsage usage = HeapMemorySizeUtil.safeGetHeapMemoryUsage();
if (usage != null) {
heapMax = usage.getMax();
}
long globalMemStoreLimit = (long) (heapMax * HeapMemorySizeUtil.getGlobalMemStorePercent(conf,
false));
int chunkSize = conf.getInt(HeapMemStoreLAB.CHUNK_SIZE_KEY,
HeapMemStoreLAB.CHUNK_SIZE_DEFAULT);
int maxCount = (int) (globalMemStoreLimit * poolSizePercentage / chunkSize);
float initialCountPercentage = conf.getFloat(CHUNK_POOL_INITIALSIZE_KEY,
POOL_INITIAL_SIZE_DEFAULT);
if (initialCountPercentage > 1.0 || initialCountPercentage < 0) {
throw new IllegalArgumentException(CHUNK_POOL_INITIALSIZE_KEY
+ " must be between 0.0 and 1.0");
}
int initialCount = (int) (initialCountPercentage * maxCount);
LOG.info("Allocating MemStoreChunkPool with chunk size " + StringUtils.byteDesc(chunkSize)
+ ", max count " + maxCount + ", initial count " + initialCount);
GLOBAL_INSTANCE = new MemStoreChunkPool(conf, chunkSize, maxCount, initialCount);
return GLOBAL_INSTANCE;
}
}
int getMaxCount() {
return this.maxCount;
}
@VisibleForTesting
static void clearDisableFlag() {
chunkPoolDisabled = false;
}
}