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https://issues.apache.org/jira/browse/RATIS-1717?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tsz-wo Sze reassigned RATIS-1717:
---------------------------------
Component/s: server
Assignee: Song Ziyang
Summary: Perf: Use global serialize buf to avoid temp buf (was: Reduce
data copy when serialize LogEntry to RaftLog)
> Perf: Use global serialize buf to avoid temp buf
> ------------------------------------------------
>
> Key: RATIS-1717
> URL: https://issues.apache.org/jira/browse/RATIS-1717
> Project: Ratis
> Issue Type: Improvement
> Components: performance, server
> Reporter: Song Ziyang
> Assignee: Song Ziyang
> Priority: Major
> Attachments: 762_review.patch
>
> Time Spent: 0.5h
> Remaining Estimate: 0h
>
> In current implementation, before a log entry is serialized to RaftLog, it
> first needs to be serialized to a byte array[1], and then be written to
> FileChannel using directByteBuffer[2]. It requires two data copies, one from
> LogEntryProto to byte array, one from byte array to direct ByteBuffer.
> We can reduce the data copy by *serializing LogEntry to directByteBuffer,
> removing the byte array:*
> # We need a directByteBuffer large enough to hold a single log
> (maxBufferSize).
> # When we need to serialize a log entry to RaftLog, first we check whether
> there's enough space remained in directByteBuffer. If not, we flush the
> directByteBuffer to FileChannel. Otherwise we serialize the data directly
> into directByteBuffer.
> # When data buffered in directByteBuffer reaches the threshold (say 64KB),
> we flush the directByteBuffer, the same as current implementation.
> [1]
> [https://github.com/apache/ratis/blob/289db3ae64e8cf620eba882468dda661af0439bc/ratis-server/src/main/java/org/apache/ratis/server/raftlog/segmented/SegmentedRaftLogOutputStream.java#L96]
> [2]
> [https://github.com/apache/ratis/blob/289db3ae64e8cf620eba882468dda661af0439bc/ratis-server/src/main/java/org/apache/ratis/server/raftlog/segmented/BufferedWriteChannel.java#L65]
>
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