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From "Steve Loughran (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-3694) if MiniDFS startup time could be improved, testing time would be reduced
Date Wed, 09 Jul 2008 09:23:31 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-3694?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12611952#action_12611952

Steve Loughran commented on HADOOP-3694:

A quick search here points a bit at entropy related https delays

This is backed up by email from Greg Wilkins
"the culprit that comes to mind for startup delays is the fact that
jetty uses a securerandom for the session manager, which needs enough
entropy in the operating systems random source before it starts.

If the machine is newly started or other things have consumed that entropy,
then it can be slow starting while the OS waits for interrupts and
other such stuff to create random numbers.

A simple threaddump during this pause should answer this.

If it is that- there are several options - including not using
sessions, or a less secure random number generator."

> if MiniDFS startup time could be improved, testing time would be reduced
> ------------------------------------------------------------------------
>                 Key: HADOOP-3694
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3694
>             Project: Hadoop Core
>          Issue Type: Improvement
>          Components: test
>    Affects Versions: 0.19.0
>            Reporter: Steve Loughran
> Its taking me 140 minutes to run a test build; looking into the test results its the
20s startup delay of every MiniDFS cluster that is slowing things down. If we could find out
why it is taking so long and cut it down, every test case that relied on a cluster would be
speeded up. 

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