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https://issues.apache.org/jira/browse/HADOOP-7901?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13166644#comment-13166644
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Robert Joseph Evans commented on HADOOP-7901:
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I have not measured any contention in the Configuration object. That is a very
good point I really should not be doing optimizations without measuring first
to know if they are needless or not. I really should rename this measure lock
contention in Configuration object and then possibly use Read/Write Locks.
This was filed partly in response to MAPREDUCE-3519. There was a deadlock
introduced because one thread grabbed a lock on a Configuration object and then
tried to grab a different lock while a separate thread tried to grab the locks
in reverse order. This seems especially odd to me because my gut feeling is
that most of the time all we are trying to do is to read data from
Configuration. Very rarely do we want to change it, so I thought that it would
be a potential performance improvement, in addition to removing some of the
potential for these deadlocks in the future.
So before doing any code changes I will measure the level of lock contention.
> Have Configuration use Read/Write Locks
> ---------------------------------------
>
> Key: HADOOP-7901
> URL: https://issues.apache.org/jira/browse/HADOOP-7901
> Project: Hadoop Common
> Issue Type: Improvement
> Components: conf
> Affects Versions: 0.23.1
> Reporter: Robert Joseph Evans
> Assignee: Robert Joseph Evans
>
> We can potentially improve performance by moving to read/write locks for
> configuration instead of the current synchronization.
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