| /** |
| * 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.hdfs.server.datanode.fsdataset.impl; |
| |
| import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATANODE_CACHE_REVOCATION_TIMEOUT_MS; |
| import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATANODE_CACHE_REVOCATION_TIMEOUT_MS_DEFAULT; |
| import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATANODE_CACHE_REVOCATION_POLLING_MS; |
| import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATANODE_CACHE_REVOCATION_POLLING_MS_DEFAULT; |
| |
| import com.google.common.base.Preconditions; |
| import com.google.common.util.concurrent.ThreadFactoryBuilder; |
| |
| import java.io.FileInputStream; |
| import java.io.FileNotFoundException; |
| import java.io.IOException; |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| import java.util.Iterator; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.Map.Entry; |
| import java.util.Set; |
| import java.util.concurrent.Executor; |
| import java.util.concurrent.LinkedBlockingQueue; |
| import java.util.concurrent.ThreadFactory; |
| import java.util.concurrent.ThreadPoolExecutor; |
| import java.util.concurrent.ScheduledThreadPoolExecutor; |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.atomic.AtomicLong; |
| |
| import org.apache.commons.io.IOUtils; |
| import org.apache.commons.lang3.time.DurationFormatUtils; |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.fs.ChecksumException; |
| import org.apache.hadoop.hdfs.ExtendedBlockId; |
| import org.apache.hadoop.hdfs.protocol.BlockListAsLongs; |
| import org.apache.hadoop.hdfs.protocol.ExtendedBlock; |
| import org.apache.hadoop.hdfs.server.datanode.DNConf; |
| import org.apache.hadoop.hdfs.server.datanode.DatanodeUtil; |
| import org.apache.hadoop.util.Time; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| /** |
| * Manages caching for an FsDatasetImpl by using the mmap(2) and mlock(2) |
| * system calls to lock blocks into memory. Block checksums are verified upon |
| * entry into the cache. |
| */ |
| @InterfaceAudience.Private |
| @InterfaceStability.Unstable |
| public class FsDatasetCache { |
| /** |
| * MappableBlocks that we know about. |
| */ |
| private static final class Value { |
| final State state; |
| final MappableBlock mappableBlock; |
| |
| Value(MappableBlock mappableBlock, State state) { |
| this.mappableBlock = mappableBlock; |
| this.state = state; |
| } |
| } |
| |
| private enum State { |
| /** |
| * The MappableBlock is in the process of being cached. |
| */ |
| CACHING, |
| |
| /** |
| * The MappableBlock was in the process of being cached, but it was |
| * cancelled. Only the FsDatasetCache#WorkerTask can remove cancelled |
| * MappableBlock objects. |
| */ |
| CACHING_CANCELLED, |
| |
| /** |
| * The MappableBlock is in the cache. |
| */ |
| CACHED, |
| |
| /** |
| * The MappableBlock is in the process of uncaching. |
| */ |
| UNCACHING; |
| |
| /** |
| * Whether we should advertise this block as cached to the NameNode and |
| * clients. |
| */ |
| public boolean shouldAdvertise() { |
| return (this == CACHED); |
| } |
| } |
| |
| private static final Logger LOG = LoggerFactory.getLogger(FsDatasetCache |
| .class); |
| |
| /** |
| * Stores MappableBlock objects and the states they're in. |
| */ |
| private final HashMap<ExtendedBlockId, Value> mappableBlockMap = |
| new HashMap<ExtendedBlockId, Value>(); |
| |
| private final AtomicLong numBlocksCached = new AtomicLong(0); |
| |
| private final FsDatasetImpl dataset; |
| |
| private final ThreadPoolExecutor uncachingExecutor; |
| |
| private final ScheduledThreadPoolExecutor deferredUncachingExecutor; |
| |
| private final long revocationMs; |
| |
| private final long revocationPollingMs; |
| |
| /** |
| * A specific cacheLoader could cache block either to DRAM or |
| * to persistent memory. |
| */ |
| private final MappableBlockLoader cacheLoader; |
| |
| private final CacheStats memCacheStats; |
| |
| /** |
| * Number of cache commands that could not be completed successfully |
| */ |
| final AtomicLong numBlocksFailedToCache = new AtomicLong(0); |
| /** |
| * Number of uncache commands that could not be completed successfully |
| */ |
| final AtomicLong numBlocksFailedToUncache = new AtomicLong(0); |
| |
| public FsDatasetCache(FsDatasetImpl dataset) throws IOException { |
| this.dataset = dataset; |
| ThreadFactory workerFactory = new ThreadFactoryBuilder() |
| .setDaemon(true) |
| .setNameFormat("FsDatasetCache-%d-" + dataset.toString()) |
| .build(); |
| this.uncachingExecutor = new ThreadPoolExecutor( |
| 0, 1, |
| 60, TimeUnit.SECONDS, |
| new LinkedBlockingQueue<Runnable>(), |
| workerFactory); |
| this.uncachingExecutor.allowCoreThreadTimeOut(true); |
| this.deferredUncachingExecutor = new ScheduledThreadPoolExecutor( |
| 1, workerFactory); |
| this.revocationMs = dataset.datanode.getConf().getLong( |
| DFS_DATANODE_CACHE_REVOCATION_TIMEOUT_MS, |
| DFS_DATANODE_CACHE_REVOCATION_TIMEOUT_MS_DEFAULT); |
| long confRevocationPollingMs = dataset.datanode.getConf().getLong( |
| DFS_DATANODE_CACHE_REVOCATION_POLLING_MS, |
| DFS_DATANODE_CACHE_REVOCATION_POLLING_MS_DEFAULT); |
| long minRevocationPollingMs = revocationMs / 2; |
| if (minRevocationPollingMs < confRevocationPollingMs) { |
| throw new RuntimeException("configured value " + |
| confRevocationPollingMs + "for " + |
| DFS_DATANODE_CACHE_REVOCATION_POLLING_MS + |
| " is too high. It must not be more than half of the " + |
| "value of " + DFS_DATANODE_CACHE_REVOCATION_TIMEOUT_MS + |
| ". Reconfigure this to " + minRevocationPollingMs); |
| } |
| this.revocationPollingMs = confRevocationPollingMs; |
| |
| this.cacheLoader = MappableBlockLoaderFactory.createCacheLoader( |
| this.getDnConf()); |
| // Both lazy writer and read cache are sharing this statistics. |
| this.memCacheStats = cacheLoader.initialize(this.getDnConf()); |
| } |
| |
| /** |
| * For persistent memory cache, create cache subdirectory specified with |
| * blockPoolId to store cache data. |
| * Recover the status of cache in persistent memory, if any. |
| */ |
| public void initCache(String bpid) throws IOException { |
| if (cacheLoader.isTransientCache()) { |
| return; |
| } |
| PmemVolumeManager.getInstance().createBlockPoolDir(bpid); |
| if (getDnConf().getPmemCacheRecoveryEnabled()) { |
| final Map<ExtendedBlockId, MappableBlock> keyToMappableBlock = |
| PmemVolumeManager.getInstance().recoverCache(bpid, cacheLoader); |
| Set<Map.Entry<ExtendedBlockId, MappableBlock>> entrySet |
| = keyToMappableBlock.entrySet(); |
| for (Map.Entry<ExtendedBlockId, MappableBlock> entry : entrySet) { |
| mappableBlockMap.put(entry.getKey(), |
| new Value(keyToMappableBlock.get(entry.getKey()), State.CACHED)); |
| numBlocksCached.addAndGet(1); |
| dataset.datanode.getMetrics().incrBlocksCached(1); |
| } |
| } |
| } |
| |
| DNConf getDnConf() { |
| return this.dataset.datanode.getDnConf(); |
| } |
| |
| /** |
| * Get the cache path if the replica is cached into persistent memory. |
| */ |
| String getReplicaCachePath(String bpid, long blockId) throws IOException { |
| if (cacheLoader.isTransientCache() || |
| !isCached(bpid, blockId)) { |
| return null; |
| } |
| ExtendedBlockId key = new ExtendedBlockId(blockId, bpid); |
| return PmemVolumeManager.getInstance().getCachePath(key); |
| } |
| |
| /** |
| * Get cache address on persistent memory for read operation. |
| * The cache address comes from PMDK lib function when mapping |
| * block to persistent memory. |
| * |
| * @param bpid blockPoolId |
| * @param blockId blockId |
| * @return address |
| */ |
| long getCacheAddress(String bpid, long blockId) { |
| if (cacheLoader.isTransientCache() || |
| !isCached(bpid, blockId)) { |
| return -1; |
| } |
| if (!(cacheLoader.isNativeLoader())) { |
| return -1; |
| } |
| ExtendedBlockId key = new ExtendedBlockId(blockId, bpid); |
| MappableBlock mappableBlock = mappableBlockMap.get(key).mappableBlock; |
| return mappableBlock.getAddress(); |
| } |
| |
| /** |
| * @return List of cached blocks suitable for translation into a |
| * {@link BlockListAsLongs} for a cache report. |
| */ |
| synchronized List<Long> getCachedBlocks(String bpid) { |
| List<Long> blocks = new ArrayList<Long>(); |
| for (Iterator<Entry<ExtendedBlockId, Value>> iter = |
| mappableBlockMap.entrySet().iterator(); iter.hasNext(); ) { |
| Entry<ExtendedBlockId, Value> entry = iter.next(); |
| if (entry.getKey().getBlockPoolId().equals(bpid)) { |
| if (entry.getValue().state.shouldAdvertise()) { |
| blocks.add(entry.getKey().getBlockId()); |
| } |
| } |
| } |
| return blocks; |
| } |
| |
| /** |
| * Attempt to begin caching a block. |
| */ |
| synchronized void cacheBlock(long blockId, String bpid, |
| String blockFileName, long length, long genstamp, |
| Executor volumeExecutor) { |
| ExtendedBlockId key = new ExtendedBlockId(blockId, bpid); |
| Value prevValue = mappableBlockMap.get(key); |
| if (prevValue != null) { |
| LOG.debug("Block with id {}, pool {} already exists in the " |
| + "FsDatasetCache with state {}", blockId, bpid, prevValue.state |
| ); |
| numBlocksFailedToCache.incrementAndGet(); |
| return; |
| } |
| mappableBlockMap.put(key, new Value(null, State.CACHING)); |
| volumeExecutor.execute( |
| new CachingTask(key, blockFileName, length, genstamp)); |
| LOG.debug("Initiating caching for Block with id {}, pool {}", blockId, |
| bpid); |
| } |
| |
| synchronized void uncacheBlock(String bpid, long blockId) { |
| ExtendedBlockId key = new ExtendedBlockId(blockId, bpid); |
| Value prevValue = mappableBlockMap.get(key); |
| boolean deferred = false; |
| |
| if (cacheLoader.isTransientCache() && !dataset.datanode. |
| getShortCircuitRegistry().processBlockMunlockRequest(key)) { |
| deferred = true; |
| } |
| if (prevValue == null) { |
| LOG.debug("Block with id {}, pool {} does not need to be uncached, " |
| + "because it is not currently in the mappableBlockMap.", blockId, |
| bpid); |
| numBlocksFailedToUncache.incrementAndGet(); |
| return; |
| } |
| switch (prevValue.state) { |
| case CACHING: |
| LOG.debug("Cancelling caching for block with id {}, pool {}.", blockId, |
| bpid); |
| mappableBlockMap.put(key, |
| new Value(prevValue.mappableBlock, State.CACHING_CANCELLED)); |
| break; |
| case CACHED: |
| mappableBlockMap.put(key, |
| new Value(prevValue.mappableBlock, State.UNCACHING)); |
| if (deferred) { |
| if (LOG.isDebugEnabled()) { |
| LOG.debug("{} is anchored, and can't be uncached now. Scheduling it " + |
| "for uncaching in {} ", |
| key, DurationFormatUtils.formatDurationHMS(revocationPollingMs)); |
| } |
| deferredUncachingExecutor.schedule( |
| new UncachingTask(key, revocationMs), |
| revocationPollingMs, TimeUnit.MILLISECONDS); |
| } else { |
| LOG.debug("{} has been scheduled for immediate uncaching.", key); |
| uncachingExecutor.execute(new UncachingTask(key, 0)); |
| } |
| break; |
| default: |
| LOG.debug("Block with id {}, pool {} does not need to be uncached, " |
| + "because it is in state {}.", blockId, bpid, prevValue.state); |
| numBlocksFailedToUncache.incrementAndGet(); |
| break; |
| } |
| } |
| |
| /** |
| * Try to reserve more bytes. |
| * |
| * @param count The number of bytes to add. We will round this |
| * up to the page size. |
| * |
| * @return The new number of usedBytes if we succeeded; |
| * -1 if we failed. |
| */ |
| long reserve(long count) { |
| return memCacheStats.reserve(count); |
| } |
| |
| /** |
| * Release some bytes that we're using. |
| * |
| * @param count The number of bytes to release. We will round this |
| * up to the page size. |
| * |
| * @return The new number of usedBytes. |
| */ |
| long release(long count) { |
| return memCacheStats.release(count); |
| } |
| |
| /** |
| * Release some bytes that we're using rounded down to the page size. |
| * |
| * @param count The number of bytes to release. We will round this |
| * down to the page size. |
| * |
| * @return The new number of usedBytes. |
| */ |
| long releaseRoundDown(long count) { |
| return memCacheStats.releaseRoundDown(count); |
| } |
| |
| /** |
| * Get the OS page size. |
| * |
| * @return the OS page size. |
| */ |
| long getOsPageSize() { |
| return memCacheStats.getPageSize(); |
| } |
| |
| /** |
| * Round up to the OS page size. |
| */ |
| long roundUpPageSize(long count) { |
| return memCacheStats.roundUpPageSize(count); |
| } |
| |
| /** |
| * Background worker that mmaps, mlocks, and checksums a block |
| */ |
| private class CachingTask implements Runnable { |
| private final ExtendedBlockId key; |
| private final String blockFileName; |
| private final long length; |
| private final long genstamp; |
| |
| CachingTask(ExtendedBlockId key, String blockFileName, long length, long genstamp) { |
| this.key = key; |
| this.blockFileName = blockFileName; |
| this.length = length; |
| this.genstamp = genstamp; |
| } |
| |
| @Override |
| public void run() { |
| boolean success = false; |
| FileInputStream blockIn = null, metaIn = null; |
| MappableBlock mappableBlock = null; |
| ExtendedBlock extBlk = new ExtendedBlock(key.getBlockPoolId(), |
| key.getBlockId(), length, genstamp); |
| long newUsedBytes = cacheLoader.reserve(key, length); |
| boolean reservedBytes = false; |
| try { |
| if (newUsedBytes < 0) { |
| LOG.warn("Failed to cache " + key + ": could not reserve " + |
| "more bytes in the cache: " + cacheLoader.getCacheCapacity() + |
| " exceeded when try to reserve " + length + "bytes."); |
| return; |
| } |
| reservedBytes = true; |
| try { |
| blockIn = (FileInputStream)dataset.getBlockInputStream(extBlk, 0); |
| metaIn = DatanodeUtil.getMetaDataInputStream(extBlk, dataset); |
| } catch (ClassCastException e) { |
| LOG.warn("Failed to cache " + key + |
| ": Underlying blocks are not backed by files.", e); |
| return; |
| } catch (FileNotFoundException e) { |
| LOG.info("Failed to cache " + key + ": failed to find backing " + |
| "files."); |
| return; |
| } catch (IOException e) { |
| LOG.warn("Failed to cache " + key + ": failed to open file", e); |
| return; |
| } |
| |
| try { |
| mappableBlock = cacheLoader.load(length, blockIn, metaIn, |
| blockFileName, key); |
| } catch (ChecksumException e) { |
| // Exception message is bogus since this wasn't caused by a file read |
| LOG.warn("Failed to cache " + key + ": checksum verification failed."); |
| return; |
| } catch (IOException e) { |
| LOG.warn("Failed to cache the block [key=" + key + "]!", e); |
| return; |
| } |
| |
| synchronized (FsDatasetCache.this) { |
| Value value = mappableBlockMap.get(key); |
| Preconditions.checkNotNull(value); |
| Preconditions.checkState(value.state == State.CACHING || |
| value.state == State.CACHING_CANCELLED); |
| if (value.state == State.CACHING_CANCELLED) { |
| mappableBlockMap.remove(key); |
| LOG.warn("Caching of " + key + " was cancelled."); |
| return; |
| } |
| mappableBlockMap.put(key, new Value(mappableBlock, State.CACHED)); |
| } |
| LOG.debug("Successfully cached {}. We are now caching {} bytes in" |
| + " total.", key, newUsedBytes); |
| // Only applicable to DRAM cache. |
| if (cacheLoader.isTransientCache()) { |
| dataset.datanode. |
| getShortCircuitRegistry().processBlockMlockEvent(key); |
| } |
| numBlocksCached.addAndGet(1); |
| dataset.datanode.getMetrics().incrBlocksCached(1); |
| success = true; |
| } finally { |
| IOUtils.closeQuietly(blockIn); |
| IOUtils.closeQuietly(metaIn); |
| if (!success) { |
| if (reservedBytes) { |
| cacheLoader.release(key, length); |
| } |
| LOG.debug("Caching of {} was aborted. We are now caching only {} " |
| + "bytes in total.", key, cacheLoader.getCacheUsed()); |
| IOUtils.closeQuietly(mappableBlock); |
| numBlocksFailedToCache.incrementAndGet(); |
| |
| synchronized (FsDatasetCache.this) { |
| mappableBlockMap.remove(key); |
| } |
| } |
| } |
| } |
| } |
| |
| private class UncachingTask implements Runnable { |
| private final ExtendedBlockId key; |
| private final long revocationTimeMs; |
| |
| UncachingTask(ExtendedBlockId key, long revocationDelayMs) { |
| this.key = key; |
| if (revocationDelayMs == 0) { |
| this.revocationTimeMs = 0; |
| } else { |
| this.revocationTimeMs = revocationDelayMs + Time.monotonicNow(); |
| } |
| } |
| |
| private boolean shouldDefer() { |
| // Currently, defer condition is just checked for DRAM cache case. |
| if (!cacheLoader.isTransientCache()) { |
| return false; |
| } |
| |
| /* If revocationTimeMs == 0, this is an immediate uncache request. |
| * No clients were anchored at the time we made the request. */ |
| if (revocationTimeMs == 0) { |
| return false; |
| } |
| /* Let's check if any clients still have this block anchored. */ |
| boolean anchored = |
| !dataset.datanode.getShortCircuitRegistry(). |
| processBlockMunlockRequest(key); |
| if (!anchored) { |
| LOG.debug("Uncaching {} now that it is no longer in use " + |
| "by any clients.", key); |
| return false; |
| } |
| long delta = revocationTimeMs - Time.monotonicNow(); |
| if (delta < 0) { |
| LOG.warn("Forcibly uncaching {} after {} " + |
| "because client(s) {} refused to stop using it.", key, |
| DurationFormatUtils.formatDurationHMS(revocationTimeMs), |
| dataset.datanode.getShortCircuitRegistry().getClientNames(key)); |
| return false; |
| } |
| LOG.info("Replica {} still can't be uncached because some " + |
| "clients continue to use it. Will wait for {}", key, |
| DurationFormatUtils.formatDurationHMS(delta)); |
| return true; |
| } |
| |
| @Override |
| public void run() { |
| Value value; |
| |
| if (shouldDefer()) { |
| deferredUncachingExecutor.schedule( |
| this, revocationPollingMs, TimeUnit.MILLISECONDS); |
| return; |
| } |
| |
| synchronized (FsDatasetCache.this) { |
| value = mappableBlockMap.get(key); |
| } |
| Preconditions.checkNotNull(value); |
| Preconditions.checkArgument(value.state == State.UNCACHING); |
| |
| IOUtils.closeQuietly(value.mappableBlock); |
| synchronized (FsDatasetCache.this) { |
| mappableBlockMap.remove(key); |
| } |
| long newUsedBytes = cacheLoader. |
| release(key, value.mappableBlock.getLength()); |
| numBlocksCached.addAndGet(-1); |
| dataset.datanode.getMetrics().incrBlocksUncached(1); |
| if (revocationTimeMs != 0) { |
| LOG.debug("Uncaching of {} completed. usedBytes = {}", |
| key, newUsedBytes); |
| } else { |
| LOG.debug("Deferred uncaching of {} completed. usedBytes = {}", |
| key, newUsedBytes); |
| } |
| } |
| } |
| |
| // Stats related methods for FSDatasetMBean |
| |
| /** |
| * Get the approximate amount of DRAM cache space used. |
| */ |
| public long getMemCacheUsed() { |
| return memCacheStats.getCacheUsed(); |
| } |
| |
| /** |
| * Get the approximate amount of cache space used either on DRAM or |
| * on persistent memory. |
| * @return |
| */ |
| public long getCacheUsed() { |
| return cacheLoader.getCacheUsed(); |
| } |
| |
| /** |
| * Get the maximum amount of bytes we can cache on DRAM. This is a constant. |
| */ |
| public long getMemCacheCapacity() { |
| return memCacheStats.getCacheCapacity(); |
| } |
| |
| /** |
| * Get the maximum amount of bytes we can cache either on DRAM or |
| * on persistent memory. This is a constant. |
| */ |
| public long getCacheCapacity() { |
| return cacheLoader.getCacheCapacity(); |
| } |
| |
| public long getNumBlocksFailedToCache() { |
| return numBlocksFailedToCache.get(); |
| } |
| |
| public long getNumBlocksFailedToUncache() { |
| return numBlocksFailedToUncache.get(); |
| } |
| |
| public long getNumBlocksCached() { |
| return numBlocksCached.get(); |
| } |
| |
| public synchronized boolean isCached(String bpid, long blockId) { |
| ExtendedBlockId block = new ExtendedBlockId(blockId, bpid); |
| Value val = mappableBlockMap.get(block); |
| return (val != null) && val.state.shouldAdvertise(); |
| } |
| |
| /** |
| * This method can be executed during DataNode shutdown. |
| */ |
| void shutdown() { |
| cacheLoader.shutdown(); |
| } |
| } |