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Posted to issues@spark.apache.org by "Apache Spark (JIRA)" <ji...@apache.org> on 2018/04/16 08:29:00 UTC
[jira] [Commented] (SPARK-21033) fix the potential OOM in
UnsafeExternalSorter
[ https://issues.apache.org/jira/browse/SPARK-21033?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16439118#comment-16439118 ]
Apache Spark commented on SPARK-21033:
--------------------------------------
User 'wangyum' has created a pull request for this issue:
https://github.com/apache/spark/pull/21077
> fix the potential OOM in UnsafeExternalSorter
> ---------------------------------------------
>
> Key: SPARK-21033
> URL: https://issues.apache.org/jira/browse/SPARK-21033
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 2.2.0
> Reporter: Wenchen Fan
> Assignee: Wenchen Fan
> Priority: Major
> Fix For: 2.3.0
>
>
> In `UnsafeInMemorySorter`, one record may take 32 bytes: 1 `long` for pointer, 1 `long` for key-prefix, and another 2 `long`s as the temporary buffer for radix sort.
> In `UnsafeExternalSorter`, we set the `DEFAULT_NUM_ELEMENTS_FOR_SPILL_THRESHOLD` to be `1024 * 1024 * 1024 / 2`, and hoping the max size of point array to be 8 GB. However this is wrong, `1024 * 1024 * 1024 / 2 * 32` is actually 16 GB, and if we grow the point array before reach this limitation, we may hit the max-page-size error.
> Users may see exception like this on large dataset:
> {code}
> Caused by: java.lang.IllegalArgumentException: Cannot allocate a page with more than 17179869176 bytes
> at org.apache.spark.memory.TaskMemoryManager.allocatePage(TaskMemoryManager.java:241)
> at org.apache.spark.memory.MemoryConsumer.allocatePage(MemoryConsumer.java:121)
> at org.apache.spark.util.collection.unsafe.sort.UnsafeExternalSorter.acquireNewPageIfNecessary(UnsafeExternalSorter.java:374)
> at org.apache.spark.util.collection.unsafe.sort.UnsafeExternalSorter.insertRecord(UnsafeExternalSorter.java:396)
> at org.apache.spark.sql.execution.UnsafeExternalRowSorter.insertRow(UnsafeExternalRowSorter.java:94)
> ...
> {code}
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