org.apache.hadoop.hbase.io.hfile.BlockCacheUtil Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of hbase-server Show documentation
Show all versions of hbase-server Show documentation
Server functionality for HBase
/**
* 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.io.hfile;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.NavigableMap;
import java.util.NavigableSet;
import java.util.concurrent.ConcurrentSkipListMap;
import java.util.concurrent.ConcurrentSkipListSet;
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import com.fasterxml.jackson.core.JsonGenerationException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import org.apache.yetus.audience.InterfaceAudience;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.metrics.impl.FastLongHistogram;
import org.apache.hadoop.hbase.util.Bytes;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Utilty for aggregating counts in CachedBlocks and toString/toJSON CachedBlocks and BlockCaches.
* No attempt has been made at making this thread safe.
*/
@InterfaceAudience.Private
public class BlockCacheUtil {
private static final Logger LOG = LoggerFactory.getLogger(BlockCacheUtil.class);
public static final long NANOS_PER_SECOND = 1000000000;
/**
* Needed generating JSON.
*/
private static final ObjectMapper MAPPER = new ObjectMapper();
static {
MAPPER.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
MAPPER.configure(SerializationFeature.FLUSH_AFTER_WRITE_VALUE, true);
MAPPER.configure(SerializationFeature.INDENT_OUTPUT, true);
}
/**
* @param cb
* @return The block content as String.
*/
public static String toString(final CachedBlock cb, final long now) {
return "filename=" + cb.getFilename() + ", " + toStringMinusFileName(cb, now);
}
/**
* Little data structure to hold counts for a file.
* Used doing a toJSON.
*/
static class CachedBlockCountsPerFile {
private int count = 0;
private long size = 0;
private int countData = 0;
private long sizeData = 0;
private final String filename;
CachedBlockCountsPerFile(final String filename) {
this.filename = filename;
}
public int getCount() {
return count;
}
public long getSize() {
return size;
}
public int getCountData() {
return countData;
}
public long getSizeData() {
return sizeData;
}
public String getFilename() {
return filename;
}
}
/**
* @param filename
* @param blocks
* @return A JSON String of filename and counts of blocks
* @throws JsonGenerationException
* @throws JsonMappingException
* @throws IOException
*/
public static String toJSON(final String filename, final NavigableSet blocks)
throws JsonGenerationException, JsonMappingException, IOException {
CachedBlockCountsPerFile counts = new CachedBlockCountsPerFile(filename);
for (CachedBlock cb: blocks) {
counts.count++;
counts.size += cb.getSize();
BlockType bt = cb.getBlockType();
if (bt != null && bt.isData()) {
counts.countData++;
counts.sizeData += cb.getSize();
}
}
return MAPPER.writeValueAsString(counts);
}
/**
* @param cbsbf
* @return JSON string of cbsf aggregated
* @throws JsonGenerationException
* @throws JsonMappingException
* @throws IOException
*/
public static String toJSON(final CachedBlocksByFile cbsbf)
throws JsonGenerationException, JsonMappingException, IOException {
return MAPPER.writeValueAsString(cbsbf);
}
/**
* @param bc
* @return JSON string of bc content.
* @throws JsonGenerationException
* @throws JsonMappingException
* @throws IOException
*/
public static String toJSON(final BlockCache bc)
throws JsonGenerationException, JsonMappingException, IOException {
return MAPPER.writeValueAsString(bc);
}
/**
* @param cb
* @return The block content of bc as a String minus the filename.
*/
public static String toStringMinusFileName(final CachedBlock cb, final long now) {
return "offset=" + cb.getOffset() +
", size=" + cb.getSize() +
", age=" + (now - cb.getCachedTime()) +
", type=" + cb.getBlockType() +
", priority=" + cb.getBlockPriority();
}
/**
* Get a {@link CachedBlocksByFile} instance and load it up by iterating content in
* {@link BlockCache}.
* @param conf Used to read configurations
* @param bc Block Cache to iterate.
* @return Laoded up instance of CachedBlocksByFile
*/
public static CachedBlocksByFile getLoadedCachedBlocksByFile(final Configuration conf,
final BlockCache bc) {
CachedBlocksByFile cbsbf = new CachedBlocksByFile(conf);
for (CachedBlock cb: bc) {
if (cbsbf.update(cb)) break;
}
return cbsbf;
}
private static int compareCacheBlock(Cacheable left, Cacheable right,
boolean includeNextBlockMetadata) {
ByteBuffer l = ByteBuffer.allocate(left.getSerializedLength());
left.serialize(l, includeNextBlockMetadata);
ByteBuffer r = ByteBuffer.allocate(right.getSerializedLength());
right.serialize(r, includeNextBlockMetadata);
return Bytes.compareTo(l.array(), l.arrayOffset(), l.limit(),
r.array(), r.arrayOffset(), r.limit());
}
/**
* Validate that the existing and newBlock are the same without including the nextBlockMetadata,
* if not, throw an exception. If they are the same without the nextBlockMetadata,
* return the comparison.
*
* @param existing block that is existing in the cache.
* @param newBlock block that is trying to be cached.
* @param cacheKey the cache key of the blocks.
* @return comparison of the existing block to the newBlock.
*/
public static int validateBlockAddition(Cacheable existing, Cacheable newBlock,
BlockCacheKey cacheKey) {
int comparison = compareCacheBlock(existing, newBlock, false);
if (comparison != 0) {
throw new RuntimeException("Cached block contents differ, which should not have happened."
+ "cacheKey:" + cacheKey);
}
if ((existing instanceof HFileBlock) && (newBlock instanceof HFileBlock)) {
comparison = ((HFileBlock) existing).getNextBlockOnDiskSize()
- ((HFileBlock) newBlock).getNextBlockOnDiskSize();
}
return comparison;
}
/**
* Because of the region splitting, it's possible that the split key locate in the middle of a
* block. So it's possible that both the daughter regions load the same block from their parent
* HFile. When pread, we don't force the read to read all of the next block header. So when two
* threads try to cache the same block, it's possible that one thread read all of the next block
* header but the other one didn't. if the already cached block hasn't next block header but the
* new block to cache has, then we can replace the existing block with the new block for better
* performance.(HBASE-20447)
* @param blockCache BlockCache to check
* @param cacheKey the block cache key
* @param newBlock the new block which try to put into the block cache.
* @return true means need to replace existing block with new block for the same block cache key.
* false means just keep the existing block.
*/
public static boolean shouldReplaceExistingCacheBlock(BlockCache blockCache,
BlockCacheKey cacheKey, Cacheable newBlock) {
Cacheable existingBlock = blockCache.getBlock(cacheKey, false, false, false);
if (null == existingBlock) {
// Not exist now.
return true;
}
try {
int comparison = BlockCacheUtil.validateBlockAddition(existingBlock, newBlock, cacheKey);
if (comparison < 0) {
LOG.warn("Cached block contents differ by nextBlockOnDiskSize, the new block has "
+ "nextBlockOnDiskSize set. Caching new block.");
return true;
} else if (comparison > 0) {
LOG.warn("Cached block contents differ by nextBlockOnDiskSize, the existing block has "
+ "nextBlockOnDiskSize set, Keeping cached block.");
return false;
} else {
LOG.warn("Caching an already cached block: {}. This is harmless and can happen in rare "
+ "cases (see HBASE-8547)",
cacheKey);
return false;
}
} finally {
// return the block since we need to decrement the count
blockCache.returnBlock(cacheKey, existingBlock);
}
}
/**
* Use one of these to keep a running account of cached blocks by file. Throw it away when done.
* This is different than metrics in that it is stats on current state of a cache.
* See getLoadedCachedBlocksByFile
*/
@JsonIgnoreProperties({"cachedBlockStatsByFile"})
public static class CachedBlocksByFile {
private int count;
private int dataBlockCount;
private long size;
private long dataSize;
private final long now = System.nanoTime();
/**
* How many blocks to look at before we give up.
* There could be many millions of blocks. We don't want the
* ui to freeze while we run through 1B blocks... users will
* think hbase dead. UI displays warning in red when stats
* are incomplete.
*/
private final int max;
public static final int DEFAULT_MAX = 1000000;
CachedBlocksByFile() {
this(null);
}
CachedBlocksByFile(final Configuration c) {
this.max = c == null? DEFAULT_MAX: c.getInt("hbase.ui.blockcache.by.file.max", DEFAULT_MAX);
}
/**
* Map by filename. use concurent utils because we want our Map and contained blocks sorted.
*/
private NavigableMap> cachedBlockByFile = new ConcurrentSkipListMap<>();
FastLongHistogram hist = new FastLongHistogram();
/**
* @param cb
* @return True if full.... if we won't be adding any more.
*/
public boolean update(final CachedBlock cb) {
if (isFull()) return true;
NavigableSet set = this.cachedBlockByFile.get(cb.getFilename());
if (set == null) {
set = new ConcurrentSkipListSet<>();
this.cachedBlockByFile.put(cb.getFilename(), set);
}
set.add(cb);
this.size += cb.getSize();
this.count++;
BlockType bt = cb.getBlockType();
if (bt != null && bt.isData()) {
this.dataBlockCount++;
this.dataSize += cb.getSize();
}
long age = (this.now - cb.getCachedTime())/NANOS_PER_SECOND;
this.hist.add(age, 1);
return false;
}
/**
* @return True if full; i.e. there are more items in the cache but we only loaded up
* the maximum set in configuration hbase.ui.blockcache.by.file.max
* (Default: DEFAULT_MAX).
*/
public boolean isFull() {
return this.count >= this.max;
}
public NavigableMap> getCachedBlockStatsByFile() {
return this.cachedBlockByFile;
}
/**
* @return count of blocks in the cache
*/
public int getCount() {
return count;
}
public int getDataCount() {
return dataBlockCount;
}
/**
* @return size of blocks in the cache
*/
public long getSize() {
return size;
}
/**
* @return Size of data.
*/
public long getDataSize() {
return dataSize;
}
public AgeSnapshot getAgeInCacheSnapshot() {
return new AgeSnapshot(this.hist);
}
@Override
public String toString() {
AgeSnapshot snapshot = getAgeInCacheSnapshot();
return "count=" + count + ", dataBlockCount=" + dataBlockCount + ", size=" + size +
", dataSize=" + getDataSize() +
", mean age=" + snapshot.getMean() +
", min age=" + snapshot.getMin() +
", max age=" + snapshot.getMax() +
", 75th percentile age=" + snapshot.get75thPercentile() +
", 95th percentile age=" + snapshot.get95thPercentile() +
", 98th percentile age=" + snapshot.get98thPercentile() +
", 99th percentile age=" + snapshot.get99thPercentile() +
", 99.9th percentile age=" + snapshot.get99thPercentile();
}
}
}