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Comment on adding XX:PretenureSizeThreshold and making it smaller than hbase.hregion.memstore.mslab.chunksize via Liang Xie 

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1544420 13f79535-47bb-0310-9956-ffa450edef68
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Michael Stack 2013-11-22 06:41:46 +00:00
parent eab83c92ed
commit 1349b26d3a
1 changed files with 7 additions and 1 deletions
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src/main/docbkx/performance.xml
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@ -138,7 +138,13 @@
</para>
<para>If you have a write-heavy workload, check out
<link xlink:href="https://issues.apache.org/jira/browse/HBASE-8163">HBASE-8163 MemStoreChunkPool: An improvement for JAVA GC when using MSLAB</link>.
It describes configurations to lower the amount of young GC during write-heavy loadings.</para>
It describes configurations to lower the amount of young GC during write-heavy loadings. If you do not have HBASE-8163 installed, and you are
trying to improve your young GC times, one trick to consider -- courtesy of our Liang Xie -- is to set the GC config <varname>-XX:PretenureSizeThreshold</varname> in <filename>hbase-env.sh</filename>
to be just smaller than the size of <varname>hbase.hregion.memstore.mslab.chunksize</varname> so MSLAB allocations happen in the
tenured space directly rather than first in the young gen. You'd do this because these MSLAB allocations are going to likely make it
to the old gen anyways and rather than pay the price of a copies between s0 and s1 in eden space followed by the copy up from
young to old gen after the MSLABs have achieved sufficient tenure, save a bit of YGC churn and allocate in the old gen directly.
</para>
<para>For more information about GC logs, see <xref linkend="trouble.log.gc" />.
</para>
</section>