[jira] [Commented] (HBASE-4487) The increment operation can release the rowlock before sync-ing the Hlog

["Ted Yu (Commented) (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-4487?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13117047#comment-13117047 ] 

Ted Yu commented on HBASE-4487:
-------------------------------

Nice feature.
{code}
+      System.err.println("Version Mismatch between client and server" +
+                         "... command aborted.");
{code}
I think LOG should be used.

Incrementer thread should be set as Daemon thread.

For HLog.unflushedEntries, since it is used to generate txid, I wonder if there is a better name for it.

{code}
+    // method is pretty heavyweight as far a locking is concerned. The
{code}
Should be "as far as ..."
{code}
+      // write out all accumulated Entries to hdfs.
+      for (Entry e : pending) {
+        writer.append(e);
+      }
{code}
I think exception handling should be added here. What if writer.append() raises exception ? The remaining Entries would be lost ?

                
> The increment operation can release the rowlock before sync-ing the Hlog
> ------------------------------------------------------------------------
>
>                 Key: HBASE-4487
>                 URL: https://issues.apache.org/jira/browse/HBASE-4487
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: dhruba borthakur
>            Assignee: dhruba borthakur
>         Attachments: appendNoSync4.txt
>
>
> This allows for better throughput when there are hot rows.I have seen this change make a single row update improve from 400 increments/sec/server to 4000 increments/sec/server.

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