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https://issues.apache.org/jira/browse/HADOOP-4397?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Pete Wyckoff updated HADOOP-4397:
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Affects Version/s: 0.18.0
Assignee: Pete Wyckoff
> fuse-dfs causes corruptions on multi-threaded access
> ----------------------------------------------------
>
> Key: HADOOP-4397
> URL: https://issues.apache.org/jira/browse/HADOOP-4397
> Project: Hadoop Core
> Issue Type: Bug
> Components: contrib/fuse-dfs
> Affects Versions: 0.18.0, 0.18.1
> Reporter: Brian Bockelman
> Assignee: Pete Wyckoff
> Fix For: 0.18.2
>
> Attachments: HADOOP-4397.2.txt, HADOOP-4397.3.txt, HADOOP-4397.4.txt,
> hadoop-4397.out, hadoop-4397.patch
>
>
> If multiple threads in the same process perform file system reads, then
> fuse-dfs causes various problems due to the per-context buffer. I've seen
> this reflected in segmentation violations and corruptions.
> I'll attach a proposed patch which takes the "easy way" out - I surround all
> calls to dfs_read with a mutex. You will obviously get performance
> degradations through thrashing if the threads are reading different parts of
> the file (but for our application, the multi-threaded reads are very, very
> infrequent.
> If we want to have fuse-dfs writes/reads in 0.19 or 0.20, we'll probably need
> to do the same thing with writes.
> This patch could be easily integrated as stands, or a more elaborate approach
> could be taken - per-thread buffers maybe?
> Thanks as always for looking into this,
> Brian
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