cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Nate McCall <>
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

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

> 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 <
>> 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 <>
>>> 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

Co-Founder & Sr. Technical Consultant
Apache Cassandra Consulting

View raw message