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Kuhu Shukla updated YARN-2410: ------------------------------ Attachment: YARN-2410-v8.patch Correcting 80 character line limit for test > Nodemanager ShuffleHandler can possible exhaust file descriptors > ---------------------------------------------------------------- > > Key: YARN-2410 > URL: https://issues.apache.org/jira/browse/YARN-2410 > Project: Hadoop YARN > Issue Type: Bug > Components: nodemanager > Affects Versions: 2.5.0 > Reporter: Nathan Roberts > Assignee: Kuhu Shukla > Attachments: YARN-2410-v1.patch, YARN-2410-v2.patch, > YARN-2410-v3.patch, YARN-2410-v4.patch, YARN-2410-v5.patch, > YARN-2410-v6.patch, YARN-2410-v7.patch, YARN-2410-v8.patch > > > The async nature of the shufflehandler can cause it to open a huge number of > file descriptors, when it runs out it crashes. > Scenario: > Job with 6K reduces, slow start set to 0.95, about 40 map outputs per node. > Let's say all 6K reduces hit a node at about same time asking for their > outputs. Each reducer will ask for all 40 map outputs over a single socket in > a > single request (not necessarily all 40 at once, but with coalescing it is > likely to be a large number). > sendMapOutput() will open the file for random reading and then perform an > async transfer of the particular portion of this file(). This will > theoretically > happen 6000*40=240000 times which will run the NM out of file descriptors and > cause it to crash. > The algorithm should be refactored a little to not open the fds until they're > actually needed. -- This message was sent by Atlassian JIRA (v6.3.4#6332)