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From "Josh Elser (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-3297) FileManager semaphore acquisition may block Root and Metadata scans
Date Tue, 04 Nov 2014 20:44:47 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-3297?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14196745#comment-14196745
] 

Josh Elser commented on ACCUMULO-3297:
--------------------------------------

Great find, [~phrocker]! Gave it a quick look and I agree with your assessment.

We have (at least) one other place where resources for metadata are just used. Long term,
we should make separate resource mgmt for metadata/root instead of just blindly using them,
but this should help in the meantime.

> FileManager semaphore acquisition may block Root and Metadata scans
> -------------------------------------------------------------------
>
>                 Key: ACCUMULO-3297
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-3297
>             Project: Accumulo
>          Issue Type: Bug
>          Components: tserver
>    Affects Versions: 1.6.1
>         Environment: Tserver
>            Reporter: marco polo
>             Fix For: 1.6.2
>
>
> FileManager.java contains a semaphore to limit the max open files when calling acquireUninterruptibly(
# permits ) when opening the readers. If scans against all tables causes the number of max
open permits to exceed the configured system property, scans against the metadata and root
extents will block until other readers are released.
> This should be changed so that scans against the root and metadata extents proceed, despite
exceeding the number of max open files. This likely means bypassing the semaphore acquisition
for these tablets. 



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