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Posted to issues@hbase.apache.org by GitBox <gi...@apache.org> on 2021/06/14 07:45:23 UTC
[GitHub] [hbase] ben-manes commented on a change in pull request #3371: HBASE-25984: Avoid premature reuse of sync futures in FSHLog [DRAFT]
ben-manes commented on a change in pull request #3371:
URL: https://github.com/apache/hbase/pull/3371#discussion_r649731027
##########
File path: hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/SyncFutureCache.java
##########
@@ -0,0 +1,80 @@
+/*
+ * 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 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() {
+ final SyncFuture[] result = {null};
+ // Invalidate the entry if a mapping exists. We do not want it to be reused at the same time.
+ syncFutureCache.asMap().compute(Thread.currentThread(), (thread, syncFuture) -> {
+ result[0] = syncFuture;
+ return null;
+ });
Review comment:
you could simplify this by using `remove(key)` instead of a computation, e.g.
```java
SyncFuture future = syncFutureCache.asMap().remove(Thread.currentThread());
return (future == null) ? new SyncFuture() : future;
```
##########
File path: hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/SyncFutureCache.java
##########
@@ -0,0 +1,80 @@
+/*
+ * 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 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() {
+ final SyncFuture[] result = {null};
+ // Invalidate the entry if a mapping exists. We do not want it to be reused at the same time.
+ syncFutureCache.asMap().compute(Thread.currentThread(), (thread, syncFuture) -> {
+ result[0] = syncFuture;
+ return null;
+ });
+ if (result[0] != null) {
+ return result[0];
+ }
+ return new SyncFuture();
+ }
+
+ /**
+ * Offers the sync future back to the cache for reuse.
+ */
+ public void offer(SyncFuture syncFuture) {
+ syncFutureCache.asMap().putIfAbsent(syncFuture.getThread(), syncFuture);
+ }
+
+ public void cleanUp() {
+ if (syncFutureCache != null) {
+ syncFutureCache.invalidateAll();
+ }
+ }
Review comment:
This might be a confusing method name, as `cleanUp` for the cache lib means that pending maintenance work is performed immediately (e.g. discarding any expired entries). It doesn't clear the cache like this does, so a user might be surprised by whichever mental model they have. Instead, please call this `clear`, `invalidateAll`, etc to avoid conflicting names.
##########
File path: hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/SyncFutureCache.java
##########
@@ -0,0 +1,80 @@
+/*
+ * 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 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)
Review comment:
I'm not sure if there is a benefit over a `ThreadLocal` in your case. The expiration time here seems to be only to evict when the thread dies, which a TL does automatically. A `weakKey` cache might be the closest equivalent to that.
##########
File path: hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/SyncFutureCache.java
##########
@@ -0,0 +1,80 @@
+/*
+ * 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 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)
Review comment:
It also looks like your on 2.8.1, whereas a putIfAbsent optimization was added in [2.8.2](https://github.com/ben-manes/caffeine/releases/tag/v2.8.2) to avoid locking if the entry is present. That might help.
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