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https://issues.apache.org/jira/browse/ACCUMULO-3508?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15060689#comment-15060689
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Christopher Tubbs commented on ACCUMULO-3508:
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Should this be backported to 1.6.5 and/or 1.7.1, since it was originally
reported against 1.6.0?
> Zoocache utilizes course grained locking causing unnecessary synchronization
> in many tserver ops
> ------------------------------------------------------------------------------------------------
>
> Key: ACCUMULO-3508
> URL: https://issues.apache.org/jira/browse/ACCUMULO-3508
> Project: Accumulo
> Issue Type: Sub-task
> Components: fate
> Affects Versions: 1.6.0
> Reporter: marco polo
> Assignee: marco polo
> Priority: Minor
> Fix For: 1.8.0
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Through jstacking I have observed busy tablet server threads waiting for the
> Zoocache to be updated or even read. Profiling via yourkit indicates
> potential deadlocks when threads wait for a long period of time ( in my case
> my waits were 10+s ) when many scans were running against my instance.
> My patch, which is forthcoming, removes synchronization and utilizes a
> reentrant read/write lock (RERWL) to synchronize the maps. My initial design
> utilized concurrent hash maps, but the design of existence becomes simpler
> and changes fewer by using the RERWL.
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