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https://issues.apache.org/jira/browse/HBASE-21150?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16604347#comment-16604347
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Duo Zhang commented on HBASE-21150:
-----------------------------------
Anyway, why do you call a containsKey in register method as well as that we
will do a get in registerHelper? And the same pattern is in the method
getOrCreateTableSource, we do a get, and then a get again in the registerHelper
method. What do you think?
Anyway, for me, you have a register method, and also a getOrCreate method,
first the name is not aligned, one is register and the other is create, and
second, you have a register method but another method could also do
registration?
> 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
> Assignee: Ted Yu
> Priority: Minor
> Fix For: 3.0.0, 2.2.0
>
> Attachments: 21150.v1.txt, 21150.v2.txt, 21150.v3.txt, 21150.v4.txt,
> 21150.v4.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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