[jira] [Comment Edited] (TEZ-1911) MergeManager's unconditionalReserve() should check for memory limits before allocating memory to IntermediateMemoryToMemoryMerger

["Rajesh Balamohan (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TEZ-1911?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15151597#comment-15151597 ] 

Rajesh Balamohan edited comment on TEZ-1911 at 2/18/16 2:20 AM:
----------------------------------------------------------------

Patch merges segments such that it does not overshoot memory limit.  [~sseth] Please review when you find time.


was (Author: rajesh.balamohan):
Patch merges segments such that it does not overshoot memory limit. 

> MergeManager's unconditionalReserve() should check for memory limits before allocating memory to IntermediateMemoryToMemoryMerger
> ---------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: TEZ-1911
>                 URL: https://issues.apache.org/jira/browse/TEZ-1911
>             Project: Apache Tez
>          Issue Type: Bug
>            Reporter: Rajesh Balamohan
>            Assignee: Rajesh Balamohan
>         Attachments: TEZ-1911.1.patch
>
>
> Currently, IntermediateMemoryToMemoryMerger invokes unconditionalReserve() to get the memory needed for intermediate mem-to-mem merging.  It could potentially cause issue in the following scenario
> 1. tez.runtime.io.sort.factor set to 100 and assume shuffled data (e.g 60% memory occupied) haven't reached TEZ_RUNTIME_SHUFFLE_MERGE_PERCENT_DEFAULT
> 2. Assume that it reaches the sort.factor threshold before reaching merge threshold.  This would kick in IntermediateMemoryToMemoryMerger.
> In IntermediateMemoryToMemoryMerger, it would try to allocate additional 60% without any boundary checks.  This could lead to OOM depending on the tez.runtime.io.sort.mb setting.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)