From b2a45606481a6da6e1f68d14d1095a8dcf2a0e57 Mon Sep 17 00:00:00 2001 From: Liwei Lin Date: Tue, 26 Apr 2016 23:08:40 -0700 Subject: [PATCH] [SPARK-14911] [CORE] Fix a potential data race in TaskMemoryManager ## What changes were proposed in this pull request? [[SPARK-13210][SQL] catch OOM when allocate memory and expand array](https://github.com/apache/spark/commit/37bc203c8dd5022cb11d53b697c28a737ee85bcc) introduced an `acquiredButNotUsed` field, but it might not be correctly synchronized: - the write `acquiredButNotUsed += acquired` is guarded by `this` lock (see [here](https://github.com/apache/spark/blame/master/core/src/main/java/org/apache/spark/memory/TaskMemoryManager.java#L271)); - the read `memoryManager.releaseExecutionMemory(acquiredButNotUsed, taskAttemptId, tungstenMemoryMode)` (see [here](https://github.com/apache/spark/blame/master/core/src/main/java/org/apache/spark/memory/TaskMemoryManager.java#L400)) might not be correctly synchronized, and thus might not see `acquiredButNotUsed`'s most recent value. This patch makes `acquiredButNotUsed` volatile to fix this. ## How was this patch tested? This should be covered by existing suits. Author: Liwei Lin Closes #12681 from lw-lin/fix-acquiredButNotUsed. --- .../main/java/org/apache/spark/memory/TaskMemoryManager.java | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/core/src/main/java/org/apache/spark/memory/TaskMemoryManager.java b/core/src/main/java/org/apache/spark/memory/TaskMemoryManager.java index 6b7d9aa20f..2796114fc5 100644 --- a/core/src/main/java/org/apache/spark/memory/TaskMemoryManager.java +++ b/core/src/main/java/org/apache/spark/memory/TaskMemoryManager.java @@ -114,7 +114,7 @@ public class TaskMemoryManager { /** * The amount of memory that is acquired but not used. */ - private long acquiredButNotUsed = 0L; + private volatile long acquiredButNotUsed = 0L; /** * Construct a new TaskMemoryManager.