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From S C <as...@outlook.com>
Subject RE: Flush writer all time blocked
Date Thu, 29 Aug 2013 18:23:58 GMT
Ken,
What queue size are you referring to?

Thanks,SC

> From: ken.hancock@schange.com
> Date: Thu, 29 Aug 2013 14:21:04 -0400
> Subject: Re: Flush writer all time blocked
> To: user@cassandra.apache.org
> 
> On Thu, Aug 29, 2013 at 1:57 PM, Robert Coli <rcoli@eventbrite.com> wrote:
> > On Thu, Aug 29, 2013 at 10:49 AM, S C <asf11@outlook.com> wrote:
> >> I see a high count "All time blocked" for Flush Writer on nodetool tpstats.
> >>
> >> Is it how many blocked ever since the server was online? Can somebody explain
me what it is? I really appreciate it.
> >
> >
> > Yes.
> >
> > Flush Writer thread pool is the thread pool responsible for the part of memtable
flush that actually writes to disk.
> > If you see it with a non-zero blocked number, you have at some time written to memory
significantly faster than you
> > could flush to disk.
> 
> I don't think this is strictly true?  There's also the periodic flush
> that can cause a storm of flushes if you have multiple column
> families.  I sent out a query to the list last week on this topic but
> didn't get any responses -- I'm very interested in this topic as I've
> had to set my queue size fairly large to avoid this issue.
> 
> Ken
 		 	   		  
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