[performance]decrease IO calls when flush hlog
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Key: HBASE-4044
URL: https://issues.apache.org/jira/browse/HBASE-4044
Project: HBase
Issue Type: Improvement
Components: performance, regionserver
Reporter: mingjian
Fix For: 0.90.4
Attachments: HLog.patch
We found that the hlog flush to disk would block other write threads. When
one thread exec "doWrite(info, logKey, edit);", the others wait for
"updateLock" in HLog.java.
Why not the others add their edits into a list and wait. When sync's time,
the whole list sync to disk once. I think it will decrease the IO calls.
So Maybe we will make two lists for edits. Each thread write to the
"waledits" and wait for "updateLock". Each thread can copy the "waledits" to
"flushedits" and flush the "flushedits" to
disk once it gets "updateLock".
In my test, it can increase the write speed of 100% when I set
"hbase.regionserver.handler.count"=100.
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