Thanks to everyone who responded (I think I learned a few new tricks from seeing what you tried and how your monitor). I didn't see any patterns in JVM, OS, cassandra versions etc.
At this time I'm confident in saying CASSANDRA-2868 (and thus really http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7066129) is the culprit. On 07/12/2011 09:28 AM, Chris Burroughs 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.)? >
