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From "Andrew Wang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-5810) Unify mmap cache and short-circuit file descriptor cache
Date Wed, 12 Feb 2014 01:01:08 GMT

    [ https://issues.apache.org/jira/browse/HDFS-5810?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13898581#comment-13898581
] 

Andrew Wang commented on HDFS-5810:
-----------------------------------

Nice, we're real real close then. I realized that mmap probably has to do an inode lookup,
so that could be slow enough to warrant releasing the lock. Plus, you already did the hard
work of making it happen :)

Just two comments:

bq. ClientContext#confAsString has a dupe of socketCacheExpiry. Do we also need the mmap cache
settings here?
I don't think this comment was addressed.
* The retry counting behavior is still not quite right. Because we set the remaining tries
to -1 when we exhaust the domain peer cache, we won't ever try the TCP peer cache.

> Unify mmap cache and short-circuit file descriptor cache
> --------------------------------------------------------
>
>                 Key: HDFS-5810
>                 URL: https://issues.apache.org/jira/browse/HDFS-5810
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: hdfs-client
>    Affects Versions: 2.3.0
>            Reporter: Colin Patrick McCabe
>            Assignee: Colin Patrick McCabe
>         Attachments: HDFS-5810.001.patch, HDFS-5810.004.patch, HDFS-5810.006.patch, HDFS-5810.008.patch,
HDFS-5810.015.patch, HDFS-5810.016.patch, HDFS-5810.018.patch, HDFS-5810.019.patch, HDFS-5810.020.patch
>
>
> We should unify the client mmap cache and the client file descriptor cache.  Since mmaps
are granted corresponding to file descriptors in the cache (currently FileInputStreamCache),
they have to be tracked together to do "smarter" things like HDFS-5182.



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