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Duo Zhang commented on HBASE-21150: ----------------------------------- First, please use ConcurrentMap instead of Map MetricsTableAggregateSourceImpl, since you removed the computeIfAbsent, it is not necessary to be a ConcurrentHashMap but it still need to be a ConcurrentMap, as for different tables, we may do get and put at the same time. HashMap is not thread safe. Second, you use a thread pool to execute the registration, then it could still happen that we want to get a metrics but it is not registered yet, and cause another NPE... > 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: Bug > Reporter: Ted Yu > Assignee: Ted Yu > Priority: Major > Attachments: 21150.v1.txt, 21150.v2.txt, 21150.v3.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. > 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. -- This message was sent by Atlassian JIRA (v7.6.3#76005)