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Jim Kellerman commented on HADOOP-2139:
---------------------------------------
Strategy:
Associate memcache with HStore instead of HRegion - reduces
contention between most other ops and scanners.
If a scanner is open on a memcache, and an update arrives,
push the memcache on a stack and create a new memcache for
the update. This is unlikely to cause the generation of a
lot of memcaches since scanners don't get created nearly as
often.
All operations other than Split lock the region for read.
Locks for portions of a region will be contended at the
column level.
Splits need to lock the region for write since this is the
only operation that cannot proceed in parallel with others.
> [hbase] Increase parallelism in region servers
> ----------------------------------------------
>
> Key: HADOOP-2139
> URL: htt
ps://issues.apache.org/jira/browse/HADOOP-2139
> Project: Hadoop
> Issue Type: Improvement
> Components: contrib/hbase
> Affects Versions: 0.16.0
> Reporter: Jim Kellerman
> Assignee: Jim Kellerman
> Fix For: 0.16.0
>
>
> There are a number of paths in the region server which
block against one another including:
> - log rolling
> - cache flushes
> - region splitting
> - updates
> - scanners
> Investigate which can proceed in parallel and
mechanisms for making some operations that currently do not
run in parallel.
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