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https://issues.apache.org/jira/browse/HBASE-21150?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16604628#comment-16604628
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Ted Yu edited comment on HBASE-21150 at 9/5/18 5:08 PM:
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bq. Where is evidence that the patch makes improvement?
As I noted earlier, when adding log in the getOrCreateTableSource method of
code path for flushing, the log didn't show up with patch.
bq. Is it just the original cited 6ms instance?
That was what I observed, through the additional log.
I will resolve this issue.
was (Author: yuzhih...@gmail.com):
bq. Where is evidence that the patch makes improvement?
As I noted earlier, when adding log in the getOrCreateTableSource method of
code path for flushing, the log didn't show up with patch.
bq. Is it just the original cited 6ms instance?
That was what I observed, through the additional log.
I will resolve this issue since the comment from other committers was that the
delay is not significant.
> Avoid delay in first flushes due to overheads in table metrics registration
> ---------------------------------------------------------------------------
>
> Key: HBASE-21150
> URL: https://issues.apache.org/jira/browse/HBASE-21150
> Project: HBase
> Issue Type: Improvement
> Reporter: Ted Yu
> Priority: Minor
> Attachments: 21150.v1.txt, 21150.v2.txt, 21150.v3.txt, 21150.v4.txt,
> 21150.v4.txt, 21150.v5.txt, 21150.v6.txt, 21150.v7.txt
>
>
> After HBASE-15728 is integrated, the lazy table metrics registration results
> in penalty for the first flushes.
> Excerpt from log shows delay (note the same timestamp 08:18:23,234) :
> {code:java}
> 2018-09-02 08:18:23,232 DEBUG
> [rs(hw13463.attlocal.net,52760,1535901497280)-snapshot-pool10-thread-2]
> regionserver.MetricsTableSourceImpl(124): Creating new
> MetricsTableSourceImpl for table 'testtb-1535901500805'
> 2018-09-02 08:18:23,233 DEBUG
> [rs(hw13463.attlocal.net,52760,1535901497280)-snapshot-pool10-thread-2]
> regionserver.MetricsTableSourceImpl(137): registering metrics for testtb-
> 1535901500805
> 2018-09-02 08:18:23,234 INFO
> [rs(hw13463.attlocal.net,52760,1535901497280)-snapshot-pool10-thread-1]
> regionserver.HRegion(2822): Finished flush of dataSize ~2.29 KB/2343,
> heapSize ~5.16 KB/5280, currentSize=0 B/0 for
> fa403f6a4fb8dbc1a1c389744fce2d58 in 280ms, sequenceid=5, compaction
> requested=false
> 2018-09-02 08:18:23,234 DEBUG
> [rs(hw13463.attlocal.net,52758,1535901497238)-snapshot-pool11-thread-1]
> regionserver.MetricsTableAggregateSourceImpl(84): it took 6 ms to register
> testtb-1535901500805
> Thread[rs(hw13463.attlocal.net,52758,1535901497238)-snapshot-pool11-thread-1,5,FailOnTimeoutGroup]
> 2018-09-02 08:18:23,234 DEBUG
> [rs(hw13463.attlocal.net,52760,1535901497280)-snapshot-pool10-thread-1]
> regionserver.MetricsTableAggregateSourceImpl(84): it took 0 ms to register
> testtb-1535901500805
> Thread[rs(hw13463.attlocal.net,52760,1535901497280)-snapshot-pool10-thread-1,5,FailOnTimeoutGroup]
> 2018-09-02 08:18:23,234 DEBUG
> [rs(hw13463.attlocal.net,52762,1535901497314)-snapshot-pool9-thread-1]
> regionserver.MetricsTableAggregateSourceImpl(84): it took 6 ms to register
> testtb-1535901500805
> Thread[rs(hw13463.attlocal.net,52762,1535901497314)-snapshot-pool9-thread-1,5,FailOnTimeoutGroup]
> 2018-09-02 08:18:23,234 DEBUG
> [rs(hw13463.attlocal.net,52762,1535901497314)-snapshot-pool9-thread-2]
> regionserver.MetricsTableAggregateSourceImpl(84): it took 6 ms to register
> testtb-1535901500805
> Thread[rs(hw13463.attlocal.net,52762,1535901497314)-snapshot-pool9-thread-2,5,FailOnTimeoutGroup]
> 2018-09-02 08:18:23,234 DEBUG
> [rs(hw13463.attlocal.net,52758,1535901497238)-snapshot-pool11-thread-2]
> regionserver.MetricsTableAggregateSourceImpl(84): it took 5 ms to register
> testtb-1535901500805
> Thread[rs(hw13463.attlocal.net,52758,1535901497238)-snapshot-pool11-thread-2,5,FailOnTimeoutGroup]
> 2018-09-02 08:18:23,234 DEBUG
> [rs(hw13463.attlocal.net,52760,1535901497280)-snapshot-pool10-thread-2]
> regionserver.MetricsTableAggregateSourceImpl(84): it took 6 ms to register
> testtb-1535901500805
> Thread[rs(hw13463.attlocal.net,52760,1535901497280)-snapshot-pool10-thread-2,5,FailOnTimeoutGroup]
> {code}
> This is a regression in that there were multiple (6 ms) delays before the
> flush can finish, waiting for the metrics table to be registered.
> When first region of the table is opened on region server, we can proactively
> register table metrics.
> This would avoid the penalty on first flushes for the table.
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