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From "Heng Chen (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-15091) Forward-port HBASE-15031 "Fix merge of MVCC and SequenceID performance regression in branch-1.0"
Date Thu, 14 Jan 2016 07:14:39 GMT

    [ https://issues.apache.org/jira/browse/HBASE-15091?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15097746#comment-15097746
] 

Heng Chen commented on HBASE-15091:
-----------------------------------

Some questions about patch.
In fast path,  we use {{this.mvcc.completeAndWait}} under row lock,  it will wait to catch
up write point, right?
And i notice that we do {{this.mvcc.complete}} again in finally scope, why?
{code}
+        // Tell mvcc this write is complete.
+        this.mvcc.completeAndWait(walKey.getWriteEntry());
+        walKey = null;
+      } finally {
+        this.updatesLock.readLock().unlock();
+      }
+    } finally {
+      if (walKey != null) this.mvcc.complete(walKey.getWriteEntry());
+      rowLock.release();
+    }
{code}


And in slow path, the same question,  you add two lines below,  why?
{code}
+      mvcc.completeAndWait(walKey.getWriteEntry());
+      walKey = null;
{code}



> Forward-port HBASE-15031 "Fix merge of MVCC and SequenceID performance regression in
branch-1.0"
> ------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-15091
>                 URL: https://issues.apache.org/jira/browse/HBASE-15091
>             Project: HBase
>          Issue Type: Sub-task
>          Components: Performance
>            Reporter: stack
>            Priority: Blocker
>             Fix For: 1.2.0
>
>         Attachments: 15091v2.branch-1.2.patch, HBASE-15091-branch-1.2.patch, HBASE-15091-branch-1.2_v1.patch,
HBASE-15091.v1.branch-1.2.patch
>
>




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