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Posted to common-dev@hadoop.apache.org by "Brian Bockelman (JIRA)" <ji...@apache.org> on 2008/10/11 19:07:44 UTC
[jira] Updated: (HADOOP-4397) fuse-dfs causes corruptions on
multi-threaded access
[ https://issues.apache.org/jira/browse/HADOOP-4397?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Brian Bockelman updated HADOOP-4397:
------------------------------------
Attachment: hadoop-4397.patch
The attached file provides a patch which solves the problem at hand, but does not solve the "larger issue"
Feel free to use this patch directly or as food for thought for something more elaborate.
> 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: 0.18.1
> Reporter: Brian Bockelman
> Fix For: 0.18.2
>
> Attachments: 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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