incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Ken Hancock <ken.hanc...@schange.com>
Subject Re: Flush writer all time blocked
Date Thu, 29 Aug 2013 18:21:04 GMT
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

Mime
View raw message