virajjasani commented on a change in pull request #3371: URL: https://github.com/apache/hbase/pull/3371#discussion_r651715622
########## File path: hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/SyncFutureCache.java ########## @@ -0,0 +1,74 @@ +/* + * 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.wal; + +import java.util.concurrent.TimeUnit; +import org.apache.hadoop.conf.Configuration; +import org.apache.hadoop.hbase.HConstants; +import org.apache.yetus.audience.InterfaceAudience; +import org.apache.hbase.thirdparty.com.google.common.cache.Cache; +import org.apache.hbase.thirdparty.com.google.common.cache.CacheBuilder; + +/** + * A cache of {@link SyncFuture}s. This class supports two methods + * {@link SyncFutureCache#getIfPresentOrNew()} and {@link SyncFutureCache#offer()}. + * + * Usage pattern: + * SyncFuture sf = syncFutureCache.getIfPresentOrNew(); + * sf.reset(...); + * // Use the sync future + * finally: syncFutureCache.offer(sf); + * + * Offering the sync future back to the cache makes it eligible for reuse within the same thread + * context. Cache keyed by the accessing thread instance and automatically invalidated if it remains + * unused for {@link SyncFutureCache#SYNC_FUTURE_INVALIDATION_TIMEOUT_MINS} minutes. + */ +@InterfaceAudience.Private +public final class SyncFutureCache { + + private static final long SYNC_FUTURE_INVALIDATION_TIMEOUT_MINS = 2; Review comment: 2 min is good estimate? Trying to understand if we might run into overhead (cache entry getting expired followed by same entry getting created for same thread from pool) ########## File path: hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/SyncFutureCache.java ########## @@ -0,0 +1,74 @@ +/* + * 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.wal; + +import java.util.concurrent.TimeUnit; +import org.apache.hadoop.conf.Configuration; +import org.apache.hadoop.hbase.HConstants; +import org.apache.yetus.audience.InterfaceAudience; +import org.apache.hbase.thirdparty.com.google.common.cache.Cache; +import org.apache.hbase.thirdparty.com.google.common.cache.CacheBuilder; + +/** + * A cache of {@link SyncFuture}s. This class supports two methods + * {@link SyncFutureCache#getIfPresentOrNew()} and {@link SyncFutureCache#offer()}. + * + * Usage pattern: + * SyncFuture sf = syncFutureCache.getIfPresentOrNew(); + * sf.reset(...); + * // Use the sync future + * finally: syncFutureCache.offer(sf); + * + * Offering the sync future back to the cache makes it eligible for reuse within the same thread + * context. Cache keyed by the accessing thread instance and automatically invalidated if it remains + * unused for {@link SyncFutureCache#SYNC_FUTURE_INVALIDATION_TIMEOUT_MINS} minutes. + */ +@InterfaceAudience.Private +public final class SyncFutureCache { + + private static final long SYNC_FUTURE_INVALIDATION_TIMEOUT_MINS = 2; + + private final Cache<Thread, SyncFuture> syncFutureCache; + + public SyncFutureCache(final Configuration conf) { + final int handlerCount = conf.getInt(HConstants.REGION_SERVER_HANDLER_COUNT, + HConstants.DEFAULT_REGION_SERVER_HANDLER_COUNT); + syncFutureCache = CacheBuilder.newBuilder().initialCapacity(handlerCount) + .expireAfterWrite(SYNC_FUTURE_INVALIDATION_TIMEOUT_MINS, TimeUnit.MINUTES).build(); + } + + public SyncFuture getIfPresentOrNew() { + // Invalidate the entry if a mapping exists. We do not want it to be reused at the same time. + SyncFuture future = syncFutureCache.asMap().remove(Thread.currentThread()); + return (future == null) ? new SyncFuture() : future; Review comment: This suggestion was great. I think we can make this change in branch-1 as well (sorry I lost the track, not sure if branch-1 PR is still pending for merge or already merged) -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
