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From "Oleg Kibirev (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CASSANDRA-4726) Streaming sstables during repair is limited by compression
Date Wed, 26 Sep 2012 22:49:08 GMT
Oleg Kibirev created CASSANDRA-4726:
---------------------------------------

             Summary: Streaming sstables during repair is limited by compression
                 Key: CASSANDRA-4726
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4726
             Project: Cassandra
          Issue Type: Bug
          Components: Core
    Affects Versions: 1.1.5
            Reporter: Oleg Kibirev


In our benchmarks of node rebuilds, streaming SSTables is limited by sender uncompressing
them using snappy and compressing using lzf. The receiver has to reverse this process and
is likewise bottlenecked in compression code. We are therefore only able to utilize less than
1/2 of receiver's 1gbps network link in a test with one receiver and two senders.

If sstable is already compressed using snappy, it should be just sent to receiver as is. 

Here are hprof fragments excluding socket accepts and reads by idle threads:

Sender:

  4  3.14% 95.51%    6128 302816 com.ning.compress.lzf.ChunkEncoder.tryCompress
   5  1.93% 97.44%    3761 302815 java.net.SocketOutputStream.socketWrite0
   6  1.27% 98.71%    2477 301463 java.util.zip.CRC32.updateBytes
   7  0.41% 99.12%     798 302822 com.ning.compress.lzf.ChunkEncoder.tryCompress
   8  0.31% 99.43%     602 301465 org.xerial.snappy.SnappyNative.rawUncompress
   9  0.18% 99.60%     349 302820 java.net.SocketInputStream.socketRead0
  10  0.14% 99.75%     282 302817 java.net.SocketOutputStream.socketWrite0
  11  0.14% 99.89%     276 301468 java.io.FileInputStream.readBytes
  12  0.03% 99.92%      52 301929 sun.nio.ch.FileDispatcher.preClose0

Receiver:


  4  7.15% 84.63%    2782 300893 org.xerial.snappy.SnappyNative.rawCompress
   5  3.16% 87.79%    1232 300895 java.util.zip.CRC32.updateBytes
   6  2.83% 90.62%    1101 300896 com.ning.compress.lzf.LZFDecoder.decompressChunk
   7  1.50% 92.12%     583 300916 java.io.DataInputStream.readFully
   8  1.46% 93.57%     568 300921 java.io.FileDescriptor.sync
   9  1.16% 94.73%     451 300910 java.io.RandomAccessFile.writeBytes
  10  0.47% 95.20%     184 300949 sun.nio.ch.NativeThread.current
  11  0.45% 95.66%     177 300926 java.io.RandomAccessFile.getFilePointer
  12  0.31% 95.97%     121 300935 org.apache.cassandra.io.util.SequentialWriter.write


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