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From "Keith Turner (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-879) Try to speed up MiniAccumuloCluster startup time
Date Thu, 29 Nov 2012 19:20:58 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-879?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13506694#comment-13506694
] 

Keith Turner commented on ACCUMULO-879:
---------------------------------------

I have found where almost an entire second can be shaved off of startup time.   LiveTServerSet.scanServers()
makes the master aware of new tservers.   This function is called every second and when the
childen of the zookeeper tserver node changes.  I thought having the function be called when
the children changes would be good enough, but it was not.  But when the function sees a new
tserver, it tries to get a lock before notifying the master.   It does not automatically react
when the zookeeper lock event triggers.   So it takes it a second to see it did not get the
lock.   Need to make the code take action when the lock watch triggers.  Need to make it take
action for just the one tablet server.

If the code calls scan servers every 100ms instead of every 1000ms, the master reacts to new
tservers much more quickly.   Should be able to decrease the frequency that scanSevers() is
called once the lock event is handled.

                
> Try to speed up MiniAccumuloCluster startup time
> ------------------------------------------------
>
>                 Key: ACCUMULO-879
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-879
>             Project: Accumulo
>          Issue Type: Sub-task
>          Components: client
>            Reporter: Keith Turner
>             Fix For: 1.5.0
>
>
> I have looked a little bit into where the time is going when starting MiniAccumuloCluster,
but I have not looked into how it could possibly be sped up.
> First a ZooKeeper server is started and then Accumulo initialize is run.   This takes
about 1 second.   After this a master and tablet server are started.  It takes ~2 seconds
from the time the tablet server starts until the root tablet is assigned.  I think these two
places are where the bulk of the startup time is currently spent.

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