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From "Jimmy Xiang (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-6423) Writes should not block reads on blocking updates to memstores
Date Fri, 30 Nov 2012 03:49:59 GMT

     [ https://issues.apache.org/jira/browse/HBASE-6423?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Jimmy Xiang updated HBASE-6423:

    Release Note: 
Added new configuration parameters to adjust the wait time in getting a lock before acting
on a region:

hbase.busy.wait.multiplier.max (default 2)
hbase.rowlock.wait.duration (same as the default RPC timeout time)

For reading, it waits at most "hbase.rowlock.wait.duration" in getting a lock.
For writing, it waits at most "hbase.rowlock.wait.duration" * min ( #rows affected, "
hbase.busy.wait.multiplier.max"). However, it waits at most the server side call purge timeout

    Hadoop Flags: Reviewed
          Status: Patch Available  (was: Open)
> Writes should not block reads on blocking updates to memstores
> --------------------------------------------------------------
>                 Key: HBASE-6423
>                 URL: https://issues.apache.org/jira/browse/HBASE-6423
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Karthik Ranganathan
>            Assignee: Jimmy Xiang
>         Attachments: trunk-6423.patch, trunk-6423_v2.1.patch, trunk-6423_v2.patch, trunk-6423_v3.2.patch
> We have a big data use case where we turn off WAL and have a ton of reads and writes.
We found that:
> 1. flushing a memstore takes a while (GZIP compression)
> 2. incoming writes cause the new memstore to grow in an unbounded fashion
> 3. this triggers blocking memstore updates
> 4. in turn, this causes all the RPC handler threads to block on writes to that memstore
> 5. we are not able to read during this time as RPC handlers are blocked
> At a higher level, we should not hold up the RPC threads while blocking updates, and
we should build in some sort of rate control.

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