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Posted to issues@spark.apache.org by "Apache Spark (JIRA)" <ji...@apache.org> on 2017/09/27 16:36:00 UTC
[jira] [Commented] (SPARK-22147) BlockId.hashCode allocates a
StringBuilder/String on each call
[ https://issues.apache.org/jira/browse/SPARK-22147?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16182852#comment-16182852 ]
Apache Spark commented on SPARK-22147:
--------------------------------------
User 'superbobry' has created a pull request for this issue:
https://github.com/apache/spark/pull/19369
> BlockId.hashCode allocates a StringBuilder/String on each call
> --------------------------------------------------------------
>
> Key: SPARK-22147
> URL: https://issues.apache.org/jira/browse/SPARK-22147
> Project: Spark
> Issue Type: Bug
> Components: Block Manager
> Affects Versions: 2.2.0
> Reporter: Sergei Lebedev
> Priority: Minor
>
> The base class {{BlockId}} [defines|https://github.com/apache/spark/blob/master/core/src/main/scala/org/apache/spark/storage/BlockId.scala#L44] {{hashCode}} and {{equals}} for all its subclasses in terms of {{name}}. This makes the definitions of different ID types [very concise|https://github.com/apache/spark/blob/master/core/src/main/scala/org/apache/spark/storage/BlockId.scala#L52]. The downside, however, is redundant allocations. While I don't think this could be the major issue, it is still a bit disappointing to increase GC pressure on the driver for nothing. For our machine learning workloads, we've seen as much as 10% of all allocations on the driver coming from {{BlockId.hashCode}} calls done for [BlockManagerMasterEndpoint.blockLocations|https://github.com/apache/spark/blob/master/core/src/main/scala/org/apache/spark/storage/BlockManagerMasterEndpoint.scala#L54].
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