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ramkrishna.s.vasudevan commented on HBASE-16890: ------------------------------------------------ I want to ask some dumb questions. FSHLog calls WAL Sync - internally we write data to FSOutputStream and then we will call a fsdos.sync or fsdos.hflush(). So what ever was written till that point will be transffered from client to DNs and here we mark the packet as 'tosync = true'. Now there is no DFSClient here - instead you try to directly right to DN. But I could see that in any of the packets that you create you don't set 'sync = true' but only when there is endBlock() you say lastPacket=true. So what difference does this create? > Analyze the performance of AsyncWAL and fix the same > ---------------------------------------------------- > > Key: HBASE-16890 > URL: https://issues.apache.org/jira/browse/HBASE-16890 > Project: HBase > Issue Type: Sub-task > Components: wal > Affects Versions: 2.0.0 > Reporter: ramkrishna.s.vasudevan > Assignee: ramkrishna.s.vasudevan > Fix For: 2.0.0 > > Attachments: AsyncWAL_disruptor.patch, AsyncWAL_disruptor_1 > (2).patch, AsyncWAL_disruptor_3.patch, AsyncWAL_disruptor_3.patch, > AsyncWAL_disruptor_4.patch, AsyncWAL_disruptor_6.patch, > HBASE-16890-rc-v2.patch, HBASE-16890-rc-v3.patch, > HBASE-16890-remove-contention-v1.patch, HBASE-16890-remove-contention.patch, > Screen Shot 2016-10-25 at 7.34.47 PM.png, Screen Shot 2016-10-25 at 7.39.07 > PM.png, Screen Shot 2016-10-25 at 7.39.48 PM.png, Screen Shot 2016-11-04 at > 5.21.27 PM.png, Screen Shot 2016-11-04 at 5.30.18 PM.png, async.svg, > classic.svg, contention.png, contention_defaultWAL.png > > > Tests reveal that AsyncWAL under load in single node cluster performs slower > than the Default WAL. This task is to analyze and see if we could fix it. > See some discussions in the tail of JIRA HBASE-15536. -- This message was sent by Atlassian JIRA (v6.3.4#6332)