Thanks for debugging this, I'm running into the same problem. BTW, if you can ssh into your nodes, you can use jconsole over ssh: http://simplygenius.com/2010/08/jconsole-via-socks-ssh-tunnel.html
Matt On Dec 16, 2010, at Thu Dec 16, 2:39 AM, Zhu Han wrote: > Sorry for spam again. :-) > > I think I find the root cause. Here is a bug report[1] on memory leak of > ParNewGC. It is solved by OpenJDK 1.6.0_20(IcedTea6 1.9.2)[2]. > > So the suggestion is: for who runs cassandra of Ubuntu 10.04, please > upgrade OpenJDK to the latest version. > > [1] http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6824570 > [2] http://blog.fuseyism.com/index.php/2010/09/10/icedtea6-19-released/ > > best regards, > hanzhu > > > On Thu, Dec 16, 2010 at 3:10 PM, Zhu Han <schumi....@gmail.com> wrote: > >> The test node is behind a firewall. So I took some time to find a way to >> get JMX diagnostic information from it. >> >> What's interesting is, both the HeapMemoryUsage and NonHeapMemoryUsage >> reported by JVM is quite reasonable. So, it's a myth why the JVM process >> maps such a big anonymous memory region... >> >> $ java -Xmx128m -jar /tmp/cmdline-jmxclient-0.10.3.jar - localhost:8080 >> java.lang:type=Memory HeapMemoryUsage >> 12/16/2010 15:07:45 +0800 org.archive.jmx.Client HeapMemoryUsage: >> committed: 1065025536 >> init: 1073741824 >> max: 1065025536 >> used: 18295328 >> >> $java -Xmx128m -jar /tmp/cmdline-jmxclient-0.10.3.jar - localhost:8080 >> java.lang:type=Memory NonHeapMemoryUsage >> 12/16/2010 15:01:51 +0800 org.archive.jmx.Client NonHeapMemoryUsage: >> committed: 34308096 >> init: 24313856 >> max: 226492416 >> used: 21475376 >> >> If anybody is interested in it, I can provide more diagnostic information >> before I restart the instance. >> >> best regards, >> hanzhu >> >> >> >> On Thu, Dec 16, 2010 at 1:00 PM, Zhu Han <schumi....@gmail.com> wrote: >> >>> After investigating it deeper, I suspect it's native memory leak of JVM. >>> The large anonymous map on lower address space should be the native heap of >>> JVM, but not java object heap. Has anybody met it before? >>> >>> I'll try to upgrade the JVM tonight. >>> >>> best regards, >>> hanzhu >>> >>> >>> >>> On Thu, Dec 16, 2010 at 10:50 AM, Zhu Han <schumi....@gmail.com> wrote: >>> >>>> Hi, >>>> >>>> I have a test node with apache-cassandra-0.6.8 on ubuntu 10.4. The >>>> hardware environment is an OpenVZ container. JVM settings is >>>> # java -Xmx128m -version >>>> java version "1.6.0_18" >>>> OpenJDK Runtime Environment (IcedTea6 1.8.2) (6b18-1.8.2-4ubuntu2) >>>> OpenJDK 64-Bit Server VM (build 16.0-b13, mixed mode) >>>> >>>> This is the memory settings: >>>> >>>> "/usr/bin/java -ea -Xms1G -Xmx1G ..." >>>> >>>> And the ondisk footprint of sstables is very small: >>>> >>>> "#du -sh data/ >>>> "9.8M data/" >>>> >>>> The node was infrequently accessed in the last three weeks. After that, >>>> I observe the abnormal memory utilization by top: >>>> >>>> PID USER PR NI *VIRT* *RES* SHR S %CPU %MEM TIME+ >>>> COMMAND >>>> >>>> 7836 root 15 0 *3300m* *2.4g* 13m S 0 26.0 2:58.51 >>>> java >>>> >>>> The jvm heap utilization is quite normal: >>>> >>>> #sudo jstat -gc -J"-Xmx128m" 7836 >>>> S0C S1C S0U S1U *EC* *EU* *OC* >>>> *OU* *PC PU* YGC YGCT FGC FGCT >>>> GCT >>>> 8512.0 8512.0 372.8 0.0 *68160.0* *5225.7* *963392.0 508200.7 >>>> 30604.0 18373.4* 480 3.979 2 0.005 3.984 >>>> >>>> And then I try "pmap" to see the native memory mapping. *There is two >>>> large anonymous mmap regions.* >>>> >>>> 00000000080dc000 1573568K rw--- [ anon ] >>>> 00002b2afc900000 1079180K rw--- [ anon ] >>>> >>>> The second one should be JVM heap. What is the first one? Mmap of >>>> sstable should never be anonymous mmap, but file based mmap. *Is it a >>>> native memory leak? *Does cassandra allocate any DirectByteBuffer? >>>> >>>> best regards, >>>> hanzhu >>>> >>> >>> >>
