[HBASE-21721] FSHLog : reduce write#syncs() times

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.3.1, 2.1.1, 2.2.3
• Fix Version/s: 3.0.0-alpha-1, 2.3.1, 1.7.0, 2.4.0, 2.2.6
• Hadoop Flags: Reviewed
• Assignee: Bo Cui
• Reporter: Bo Cui
• Created: 15/Jan/19 03:35
• Updated: 11/Aug/20 18:12
• Resolved: 10/Aug/20 12:44

Description

the number of write#syncs can be reduced by updating the highestUnsyncedSequence：
before write#sync(), get the current highestUnsyncedSequence
after write#sync, highestSyncedSequence=highestUnsyncedSequence

 

FSHLog.java

// Some comments here
public void run()
{
    long currentSequence;
      while (!isInterrupted()) {
        int syncCount = 0;

        try {
          while (true) {
            ...
          try {
            Trace.addTimelineAnnotation("syncing writer");
            long unSyncedFlushSeq = highestUnsyncedSequence;
            writer.sync();
            Trace.addTimelineAnnotation("writer synced");
            if( unSyncedFlushSeq > currentSequence ) currentSequence = unSyncedFlushSeq;
            currentSequence = updateHighestSyncedSequence(currentSequence);
          } catch (IOException e) {
            LOG.error("Error syncing, request close of WAL", e);
            lastException = e;
          } catch (Exception e) {
           ...
    }
}

Add code
 long unSyncedFlushSeq = highestUnsyncedSequence;
if( unSyncedFlushSeq > currentSequence ) currentSequence = unSyncedFlushSeq;

Issue Links

• links to: GitHub Pull Request #2093
• links to: GitHub Pull Request #2217
• links to: GitHub Pull Request #2220