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Jean-Daniel Cryans commented on HBASE-5778: ------------------------------------------- Figured it. First there's Compressor.uncompressIntoArray that doesn't protect itself against bad dict indexes. It comes out as an IndexOutOfBoundsException and kills log splitting. Then there's FaultySequenceFileLogReader that doesn't speak compression and basically just needs to pass the compressionContext down to the HLog.Entry else it fails on a NegativeArraySizeException. The test passes now with those fixes. Will post new patches later. > Turn on WAL compression by default > ---------------------------------- > > Key: HBASE-5778 > URL: https://issues.apache.org/jira/browse/HBASE-5778 > Project: HBase > Issue Type: Improvement > Reporter: Jean-Daniel Cryans > Assignee: Jean-Daniel Cryans > Priority: Blocker > Fix For: 0.96.0 > > Attachments: 5778.addendum, 5778-addendum.txt, HBASE-5778-0.94.patch, > HBASE-5778-0.94-v2.patch, HBASE-5778-0.94-v3.patch, HBASE-5778-0.94-v4.patch, > HBASE-5778-0.94-v5.patch, HBASE-5778-0.94-v6.patch, HBASE-5778.patch, > HBASE-5778-trunk-v6.patch > > > I ran some tests to verify if WAL compression should be turned on by default. > For a use case where it's not very useful (values two order of magnitude > bigger than the keys), the insert time wasn't different and the CPU usage 15% > higher (150% CPU usage VS 130% when not compressing the WAL). > When values are smaller than the keys, I saw a 38% improvement for the insert > run time and CPU usage was 33% higher (600% CPU usage VS 450%). I'm not sure > WAL compression accounts for all the additional CPU usage, it might just be > that we're able to insert faster and we spend more time in the MemStore per > second (because our MemStores are bad when they contain tens of thousands of > values). > Those are two extremes, but it shows that for the price of some CPU we can > save a lot. My machines have 2 quads with HT, so I still had a lot of idle > CPUs. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira