[SPARK-12757] Add block-level read/write locks to BlockManager #10705
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,122 @@ | ||
| /* | ||
| * 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.spark.util.collection | ||
|
|
||
| import scala.collection.JavaConverters._ | ||
|
|
||
| import com.google.common.cache.{CacheBuilder, CacheLoader} | ||
| import com.google.common.collect.ConcurrentHashMultiset | ||
|
|
||
| import org.apache.spark.TaskContext | ||
|
|
||
| /** | ||
| * Thread-safe collection for maintaining both global and per-task reference counts for objects. | ||
| */ | ||
| private[spark] class ReferenceCounter[T] { | ||
|
There was a problem hiding this comment. Is there any reason you did it this way instead of a counter per object? Not sure how many blocks we have but this seems contention prone. There was a problem hiding this comment. I need to maintain global counts per each object as well as counts for each task (in order to automatically decrement the global counts when tasks finish) (I'm working on adding the If I stored the global count per block inside of the |
||
|
|
||
| private type TaskAttemptId = Long | ||
|
|
||
| /** | ||
| * Total references across all tasks. | ||
| */ | ||
| private[this] val allReferences = ConcurrentHashMultiset.create[T]() | ||
|
|
||
| /** | ||
| * Total references per task. Used to auto-release references upon task completion. | ||
| */ | ||
| private[this] val referencesByTask = { | ||
| // We need to explicitly box as java.lang.Long to avoid a type mismatch error: | ||
| val loader = new CacheLoader[java.lang.Long, ConcurrentHashMultiset[T]] { | ||
| override def load(t: java.lang.Long) = ConcurrentHashMultiset.create[T]() | ||
| } | ||
| CacheBuilder.newBuilder().build(loader) | ||
| } | ||
|
|
||
| /** | ||
| * Returns the total reference count, across all tasks, for the given object. | ||
| */ | ||
| def getReferenceCount(obj: T): Int = allReferences.count(obj) | ||
|
|
||
| /** | ||
| * Increments the given object's reference count for the current task. | ||
| */ | ||
| def retain(obj: T): Unit = retainForTask(currentTaskAttemptId, obj) | ||
|
|
||
| /** | ||
| * Decrements the given object's reference count for the current task. | ||
| */ | ||
| def release(obj: T): Unit = releaseForTask(currentTaskAttemptId, obj) | ||
|
|
||
| private def currentTaskAttemptId: TaskAttemptId = { | ||
| Option(TaskContext.get()).map(_.taskAttemptId()).getOrElse(-1L) | ||
| } | ||
|
|
||
| /** | ||
| * Increments the given object's reference count for the given task. | ||
| */ | ||
| def retainForTask(taskAttemptId: TaskAttemptId, obj: T): Unit = { | ||
| referencesByTask.get(taskAttemptId).add(obj) | ||
| allReferences.add(obj) | ||
| } | ||
|
|
||
| /** | ||
| * Decrements the given object's reference count for the given task. | ||
| */ | ||
| def releaseForTask(taskAttemptId: TaskAttemptId, obj: T): Unit = { | ||
| val countsForTask = referencesByTask.get(taskAttemptId) | ||
| val newReferenceCountForTask: Int = countsForTask.remove(obj, 1) - 1 | ||
| val newTotalReferenceCount: Int = allReferences.remove(obj, 1) - 1 | ||
| if (newReferenceCountForTask < 0) { | ||
| throw new IllegalStateException( | ||
| s"Task $taskAttemptId released object $obj more times than it was retained") | ||
| } | ||
| if (newTotalReferenceCount < 0) { | ||
| throw new IllegalStateException( | ||
| s"Task $taskAttemptId released object $obj more times than it was retained") | ||
| } | ||
| } | ||
|
|
||
| /** | ||
| * Release all references held by the given task, clearing that task's reference bookkeeping | ||
| * structures and updating the global reference counts. This method should be called at the | ||
| * end of a task (either by a task completion handler or in `TaskRunner.run()`). | ||
| */ | ||
| def releaseAllReferencesForTask(taskAttemptId: TaskAttemptId): Unit = { | ||
| val referenceCounts = referencesByTask.get(taskAttemptId) | ||
| referencesByTask.invalidate(taskAttemptId) | ||
| referenceCounts.entrySet().iterator().asScala.foreach { entry => | ||
| val obj = entry.getElement | ||
| val taskRefCount = entry.getCount | ||
| val newRefCount = allReferences.remove(obj, taskRefCount) - taskRefCount | ||
| if (newRefCount < 0) { | ||
| throw new IllegalStateException( | ||
| s"Task $taskAttemptId released object $obj more times than it was retained") | ||
| } | ||
| } | ||
| } | ||
|
|
||
| /** | ||
| * Return the number of map entries in this reference counter's internal data structures. | ||
| * This is used in unit tests in order to detect memory leaks. | ||
| */ | ||
| private[collection] def getNumberOfMapEntries: Long = { | ||
| allReferences.size() + | ||
| referencesByTask.size() + | ||
| referencesByTask.asMap().asScala.map(_._2.size()).sum | ||
| } | ||
| } | ||
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
Can you add a comment in this class that explains the ref counting mechanism? It can be a shorter version of the commit message.
Specifically:
What are the invariants? (explain get()) Need to call release. What does it mean if it is 0?
I slightly prefer pin count over ref count (the block manager has a reference but it is unpinned)