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https://issues.apache.org/jira/browse/HBASE-21738?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16745823#comment-16745823
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Zheng Hu commented on HBASE-21738:
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bq. What do you think is happening Zheng Hu? We are blocking writes somehow
when we flush?
Now I can only sure the time was wasted here, still not sure what's the
exactly cause. Keep working..
{code}
// Prepare flush (take a snapshot)
storeFlushCtxs.forEach((name, flush) -> {
MemStoreSize snapshotSize = flush.prepare();
totalSizeOfFlushableStores.incMemStoreSize(snapshotSize);
storeFlushableSize.put(name, snapshotSize);
});
{code}
> Latency spike happen when memstore flushing in 100% put case
> ------------------------------------------------------------
>
> Key: HBASE-21738
> URL: https://issues.apache.org/jira/browse/HBASE-21738
> Project: HBase
> Issue Type: Sub-task
> Components: Performance
> Reporter: Zheng Hu
> Assignee: Zheng Hu
> Priority: Major
> Attachments: add-some-log.patch, image-2019-01-18-14-03-28-662.png,
> log.txt
>
>
> Made some performance test for 100% put case in branch-2 before.
> We can see that there are many latency peak in p999 latency curve , and the
> peak time are almost the point time which our region is flushing.
> See the [hbase20-ssd-put-10000000000-rows-latencys-and-qps
> |https://issues.apache.org/jira/secure/attachment/12955341/12955341_image-2019-01-18-14-03-28-662.png]
> And, I used the
> [add-some-log.patch|https://issues.apache.org/jira/secure/attachment/12955342/add-some-log.patch]
> to log some time consuming when we grab the update.writeLock() to make a
> memstore snapshot. Tested again, I found those logs in [log.txt.
> |https://issues.apache.org/jira/secure/attachment/12955343/log.txt]
> Seems most of the time was consumed when taking memstore snapshot.. Let me
> dig into this.
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