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
