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From "David Sitsky (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-5623) Loosen up synchronization in FileMonitor
Date Tue, 21 Feb 2012 21:28:49 GMT

    [ https://issues.apache.org/jira/browse/DERBY-5623?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13212968#comment-13212968

David Sitsky commented on DERBY-5623:

Great - sounds good.

> Loosen up synchronization in FileMonitor
> ----------------------------------------
>                 Key: DERBY-5623
>                 URL: https://issues.apache.org/jira/browse/DERBY-5623
>             Project: Derby
>          Issue Type: Improvement
>          Components: Services
>    Affects Versions:
>            Reporter: Knut Anders Hatlen
>         Attachments: d5623-1.diff, derby-diff.txt
> When opening a large number of databases in parallel, many threads get stuck for a long
time in FileMonitor, as reported in this thread on derby-user:
> http://mail-archives.apache.org/mod_mbox/db-derby-user/201202.mbox/%3CCAEQ8c00vx0yFrwWyjm%3Dt_Yd%2BuuKGOL%3DSgpYfQuYghOOPgdN8-w%40mail.gmail.com%3E
> The synchronization in FileMonitor is only needed because the monitor instance is also
used as a shared PrivilegedExceptionAction instance. Since all databases share one FileMonitor
instance, threads that access any of these methods are serialized. If each method created
its own PrivilegedAction or PrivilegedExceptionAction instance instead of using the monitor's
run() method, these methods wouldn't need synchronization.

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