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https://issues.apache.org/jira/browse/HBASE-20188?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16442206#comment-16442206
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Duo Zhang commented on HBASE-20188:
-----------------------------------
One possible reason for the slow down I can imagine is that, since we can only
switch from pread to streaming in the shopped method of StoreScanner as the
read path offheap approach hold the references to some buffers in
StoreFileScanner, if the receive buffer is 2MB, then we can only use pread to
read the 2MB data, although we want to change to stream after 4 *
blockSize(usually 256KB). And things could be worse if you set a even larger
receive buffer.
But first, I think we need to confirm that this is the problem. So I need to
know what is the result if just use ReadType.STREAM instead of DEFAULT.
[~ram_krish]
Thanks.
> [TESTING] Performance
> ---------------------
>
> Key: HBASE-20188
> URL: https://issues.apache.org/jira/browse/HBASE-20188
> Project: HBase
> Issue Type: Umbrella
> Components: Performance
> Reporter: stack
> Assignee: stack
> Priority: Blocker
> Fix For: 2.0.0
>
> Attachments: CAM-CONFIG-V01.patch, HBASE-20188-xac.sh,
> HBASE-20188.sh, HBase 2.0 performance evaluation - 8GB(1).pdf, HBase 2.0
> performance evaluation - 8GB.pdf, HBase 2.0 performance evaluation - Basic vs
> None_ system settings.pdf, ITBLL2.5B_1.2.7vs2.0.0_cpu.png,
> ITBLL2.5B_1.2.7vs2.0.0_gctime.png, ITBLL2.5B_1.2.7vs2.0.0_iops.png,
> ITBLL2.5B_1.2.7vs2.0.0_load.png, ITBLL2.5B_1.2.7vs2.0.0_memheap.png,
> ITBLL2.5B_1.2.7vs2.0.0_memstore.png, ITBLL2.5B_1.2.7vs2.0.0_ops.png,
> ITBLL2.5B_1.2.7vs2.0.0_ops_NOT_summing_regions.png, YCSB_CPU.png,
> YCSB_GC_TIME.png, YCSB_IN_MEMORY_COMPACTION=NONE.ops.png, YCSB_MEMSTORE.png,
> YCSB_OPs.png, YCSB_in-memory-compaction=NONE.ops.png, YCSB_load.png,
> flamegraph-1072.1.svg, flamegraph-1072.2.svg, hbase-env.sh, hbase-site.xml,
> hbase-site.xml, hits.png, lock.127.workloadc.20180402T200918Z.svg,
> lock.2.memsize2.c.20180403T160257Z.svg, perregion.png, run_ycsb.sh,
> total.png, tree.txt, workloadx, workloadx
>
>
> How does 2.0.0 compare to old versions? Is it faster, slower? There is rumor
> that it is much slower, that the problem is the asyncwal writing. Does
> in-memory compaction slow us down or speed us up? What happens when you
> enable offheaping?
> Keep notes here in this umbrella issue. Need to be able to say something
> about perf when 2.0.0 ships.
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