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https://issues.apache.org/jira/browse/HBASE-17343?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15983227#comment-15983227
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Anoop Sam John commented on HBASE-17343:
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Did some PE perf testing with different value size (1K which is def in PE, 500
bytes, 100 bytes)..
When value size is lesser, the gain from Compaction is more.. Even on bigger
sized cells case, there is no significant degrade.
Also I did test along with off heap memstore feature.. The gain is more when
off heap also in place. (This is what my thinking from day one and it comes
correct as per the tests).. Off heap + Compacting Memstore comes as the best
performance.
All tests use G1GC. I also did test with global memstore size as 42% as well as
60%. In case of 42%, the Initial Heap Occupancy Percentage (IHOP) is 50% where
as in next case it is 65%. In the second case, some times I got long GC pause
so that master thinks RS is died. 1 out of 3 times I get this. In case of 50%
IHOP, this seems not coming. Remember in all these tests MSLAB is ON (which is
the default behave).
I also did test with MSLAB off. Seems this case is better performing than
MSLAB ON cases. Specially when the cell size is smaller. In those , I could
not reproduce the long GC pause.
I have a code level comment, (will say abt that in another comment) and a fix
there avoided the long GC issue in any case..
MSLAB ON vs OFF I tested specifically and seems when we have higher global
memstore size % and IHOP, the impact is more (MSLAB ON is lesser performing).
When the IHOP is set to be 50% (This defaults to 45%) , MSLAB ON is having bit
better performance (Though not too much of diff). With G1GC, we have to
check whether we should advice to turn off MSLAB.. Any way off heap memstore
is implemented using off heap MSLAB pool.. So as such it is useful only. As I
said, off heap memstore is better performing than on heap counter part and in
memory compaction there makes things even better.
Did not make a perf graphs.. Will be coming up with that soon (in a day or 2)
> Make Compacting Memstore default in 2.0 with BASIC as the default type
> ----------------------------------------------------------------------
>
> Key: HBASE-17343
> URL: https://issues.apache.org/jira/browse/HBASE-17343
> Project: HBase
> Issue Type: Bug
> Affects Versions: 2.0.0
> Reporter: ramkrishna.s.vasudevan
> Priority: Blocker
> Fix For: 2.0.0
>
> Attachments: HBASE-17343-V01.patch, HBASE-17343-V02.patch,
> HBASE-17343-V04.patch
>
>
> FYI [~anastas], [~eshcar] and [~ebortnik].
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