[jira] [Commented] (HBASE-10319) HLog should roll periodically to allow DN decommission to eventually complete.

["Jonathan Hsieh (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-10319?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13889810#comment-13889810 ] 

Jonathan Hsieh commented on HBASE-10319:
----------------------------------------

Matteo, the fix itself looks good to me.  I have a few nits on the test..  

please fix comment 

{code}
+/**
+ * Tests for conditions that should trigger RegionServer aborts when
+ * rolling the current HLog fails.
+ */
{code}

Probably want to use method name instead of class name?
{code}
+    final String tableName = this.getClass().getSimpleName();
{code}

Add timeout? (join could block forever)
{code}
+  /**
+   * Tests that the LogRoller perform the roll with some data in the log
+   */
+  @Test
+  public void testWithEdits() throws Exception {
{code}

nit: Make it "checkMinLogRolls" or "testMinLogRolls? (assert to me should just test something -- not do somethign and test something)
{code}
+  private void assertMinLogRolls(final HLog log, final int minRolls)
{code}

> HLog should roll periodically to allow DN decommission to eventually complete.
> ------------------------------------------------------------------------------
>
>                 Key: HBASE-10319
>                 URL: https://issues.apache.org/jira/browse/HBASE-10319
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Jonathan Hsieh
>            Assignee: Matteo Bertozzi
>         Attachments: HBASE-10319-v0.patch
>
>
> We encountered a situation where we had an esseitially read only table and attempted to do a clean HDFS DN decommission.  DN's cannot decomission if there are open blocks being written to currently on it.  Because the hbase Hlog file was open, had some data (hlog header), the DN could not decommission itself.  Since no new data is ever written, the existing periodic check is not activated.
> After discussing with [~atm], it seems that although an hdfs semantics change would be ideal (e.g. hbase doesn't have to be aware of hdfs decommission and the client would roll over) this would take much more effort than having hbase periodically force a log roll.  This would enable the hdfs dn con complete.



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