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From Nate McCall <n...@thelastpickle.com>
Subject Re: Recurring actions with 4 hour interval
Date Tue, 10 Dec 2013 17:27:04 GMT
Michael has a good point about the system tables - particularly hints and
batching (though neither should be a real tax unless you have bigger
issues).

If you have a monitoring system, add in the flush counters for these and
other higher traffic tables and see if there is a correlation at the four
hour mark with monitoring output of the GC statistics.


On Tue, Dec 10, 2013 at 9:58 AM, Laing, Michael
<michael.laing@nytimes.com>wrote:

> 2.0.3: system tables have a 1 hour memtable_flush_period which I have
> observed to trigger compaction on the 4 hour mark. Going by memory tho...
> -ml
>
>
> On Tue, Dec 10, 2013 at 10:31 AM, Andre Sprenger <
> andre.sprenger@getanet.de> wrote:
>
>> As far as I know there is nothing hard coded in Cassandra that kicks in
>> every 4 hours. Turn on GC logging, maybe dump the output of jstats to a
>> file and correlate this data with the Cassandra logs. Cassandra logs are
>> pretty good in telling you what is going on.
>>
>>
>> 2013/12/10 Joel Samuelsson <samuelsson.joel@gmail.com>
>>
>>> Hello,
>>>
>>> We've been having a lot of problems with extremely long GC (and still
>>> do) which I've asked about several times on this list (I can find links to
>>> those discussions if anyone is interested).
>>> We noticed a pattern that the GC pauses may be related to something
>>> happening every 4 hours. Is there anything specific happening within
>>> Cassandra with a 4 hour interval?
>>>
>>> Any help is much appreciated,
>>> Joel Samuelsson
>>>
>>
>>
>


-- 
-----------------
Nate McCall
Austin, TX
@zznate

Co-Founder & Sr. Technical Consultant
Apache Cassandra Consulting
http://www.thelastpickle.com

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