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From Sasha Dolgy <sdo...@gmail.com>
Subject Re: Survey: Cassandra/JVM Resident Set Size increase
Date Tue, 12 Jul 2011 22:23:02 GMT
I'll post more tomorrow ... However, we set up one node in a single node
cluster and have left it with no data....reviewing memory consumption
graphs...it increased daily until it gobbled (highly technical term) all
memory...the system is now running just below 100% memory usage....which i
find peculiar seeings that it is doing nothing............with no data and
no peers.
On Jul 12, 2011 3:29 PM, "Chris Burroughs" <chris.burroughs@gmail.com>
wrote:
> ### Preamble
>
> There have been several reports on the mailing list of the JVM running
> Cassandra using "too much" memory. That is, the resident set size is
>>>(max java heap size + mmaped segments) and continues to grow until the
> process swaps, kernel oom killer comes along, or performance just
> degrades too far due to the lack of space for the page cache. It has
> been unclear from these reports if there is a pattern. My hope here is
> that by comparing JVM versions, OS versions, JVM configuration etc., we
> will find something. Thank you everyone for your time.
>
>
> Some example reports:
> - http://www.mail-archive.com/user@cassandra.apache.org/msg09279.html
> -
>
http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/Very-high-memory-utilization-not-caused-by-mmap-on-sstables-td5840777.html
> - https://issues.apache.org/jira/browse/CASSANDRA-2868
> -
>
http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/OOM-or-what-settings-to-use-on-AWS-large-td6504060.html
> -
>
http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/Cassandra-memory-problem-td6545642.html
>
> For reference theories include (in no particular order):
> - memory fragmentation
> - JVM bug
> - OS/glibc bug
> - direct memory
> - swap induced fragmentation
> - some other bad interaction of cassandra/jdk/jvm/os/nio-insanity.
>
> ### Survey
>
> 1. Do you think you are experiencing this problem?
>
> 2. Why? (This is a good time to share a graph like
> http://www.twitpic.com/5fdabn or
> http://img24.imageshack.us/img24/1754/cassandrarss.png)
>
> 2. Are you using mmap? (If yes be sure to have read
> http://wiki.apache.org/cassandra/FAQ#mmap , and explain how you have
> used pmap [or another tool] to rule you mmap and top decieving you.)
>
> 3. Are you using JNA? Was mlockall succesful (it's in the logs on
startup)?
>
> 4. Is swap enabled? Are you swapping?
>
> 5. What version of Apache Cassandra are you using?
>
> 6. What is the earliest version of Apache Cassandra you recall seeing
> this problem with?
>
> 7. Have you tried the patch from CASSANDRA-2654 ?
>
> 8. What jvm and version are you using?
>
> 9. What OS and version are you using?
>
> 10. What are your jvm flags?
>
> 11. Have you tried limiting direct memory (-XX:MaxDirectMemorySize)
>
> 12. Can you characterise how much GC your cluster is doing?
>
> 13. Approximately how many read/writes per unit time is your cluster
> doing (per node or the whole cluster)?
>
> 14. How are you column families configured (key cache size, row cache
> size, etc.)?
>

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