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HBase, mail # dev - Opinions on the 'watcher' script that surrounds launched hbase daemons


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Re: Opinions on the 'watcher' script that surrounds launched hbase daemons
Nick Dimiduk 2013-06-24, 23:13
The template approach is cleaner. It sounds like it's encroaching on BigTop
territory.

On Mon, Jun 24, 2013 at 1:49 PM, Stack <[EMAIL PROTECTED]> wrote:

> New in 0.95, when you do a process listing, there are two 'hbase'
> processes.  There is the old java process itself and then there is the
> launcher script that is just hanging around waiting on the java process to
> exit so it can clear the process's znode.  Clearing the znode will mean the
> master will know sooner of the missing regionserver.  Otherwise it would
> have to wait wait on the melting of the ephemeral znode (tens of seconds).
>
> This 'watcher' was added by:
>
> HBASE-5844 Delete the region servers znode after a regions server crash
>
> What do folks think about how this facility has been implemented. I am not
> questioning the merit of fast-clear of the znode.  This is a good idea.  I
> just want to talk about how it is done.  I am not a fan [1].  Our little
> wrapper script verges into the process supervision space [2].  Rather than
> do up our own, instead should we ship templates for a few common
> supervisors and undo our custom one?
>
> Thoughts?
> St.Ack
>
>
> 1.
>
> https://issues.apache.org/jira/browse/HBASE-5844?focusedCommentId=13463409&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13463409
> 2. http://en.wikipedia.org/wiki/Process_supervision
>