Hi After running load testing for 24 hours(insert, update and delete), now no new traffic to Cassandra, but Cassnadra shows still have high load(CPU usage), from the system.log, it shows it always perform GC. I don't know why it work as that, seems memory is not low.
Here is some configuration and log, where I can find the clue why Cassandra works as this? cassandra.yaml disk_access_mode: mmap_index_only # /opt/cassandra/bin/nodetool -h 127.0.0.1 -p 6080 tpstats Pool Name Active Pending Completed Blocked All time blocked ReadStage 0 0 45387558 0 0 RequestResponseStage 0 0 96568347 0 0 MutationStage 0 0 60215102 0 0 ReadRepairStage 0 0 0 0 0 ReplicateOnWriteStage 0 0 0 0 0 GossipStage 0 0 399012 0 0 AntiEntropyStage 0 0 0 0 0 MigrationStage 0 0 30 0 0 MemtablePostFlusher 0 0 279 0 0 StreamStage 0 0 0 0 0 FlushWriter 0 0 1846 0 1052 MiscStage 0 0 0 0 0 InternalResponseStage 0 0 0 0 0 HintedHandoff 0 0 5 0 0 Message type Dropped RANGE_SLICE 0 READ_REPAIR 0 BINARY 0 READ 1 MUTATION 1390 REQUEST_RESPONSE 0 # /opt/cassandra/bin/nodetool -h 127.0.0.1 -p 6080 info Token : 56713727820156410577229101238628035242 Gossip active : true Load : 37.57 GB Generation No : 1339813956 Uptime (seconds) : 120556 Heap Memory (MB) : 3261.14 / 5984.00 Data Center : datacenter1 Rack : rack1 Exceptions : 0 INFO [ScheduledTasks:1] 2012-06-17 19:47:36,633 GCInspector.java (line 123) GC for ParNew: 222 ms for 1 collections, 2046077640 used; max is 6274678784 INFO [ScheduledTasks:1] 2012-06-17 19:48:41,714 GCInspector.java (line 123) GC for ParNew: 262 ms for 1 collections, 2228128408 used; max is 6274678784 INFO [ScheduledTasks:1] 2012-06-17 19:48:49,717 GCInspector.java (line 123) GC for ParNew: 237 ms for 1 collections, 2390412728 used; max is 6274678784 INFO [ScheduledTasks:1] 2012-06-17 19:48:57,719 GCInspector.java (line 123) GC for ParNew: 223 ms for 1 collections, 2508702896 used; max is 6274678784 INFO [ScheduledTasks:1] 2012-06-17 19:50:01,988 GCInspector.java (line 123) GC for ParNew: 232 ms for 1 collections, 2864574832 used; max is 6274678784 INFO [ScheduledTasks:1] 2012-06-17 19:50:10,075 GCInspector.java (line 123) GC for ParNew: 208 ms for 1 collections, 2964629856 used; max is 6274678784 INFO [ScheduledTasks:1] 2012-06-17 19:50:21,078 GCInspector.java (line 123) GC for ParNew: 258 ms for 1 collections, 3149127368 used; max is 6274678784 INFO [ScheduledTasks:1] 2012-06-17 19:51:26,095 GCInspector.java (line 123) GC for ParNew: 213 ms for 1 collections, 3421495400 used; max is 6274678784 INFO [ScheduledTasks:1] 2012-06-17 19:51:34,097 GCInspector.java (line 123) GC for ParNew: 218 ms for 1 collections, 3543978312 used; max is 6274678784 INFO [ScheduledTasks:1] 2012-06-17 19:52:37,229 GCInspector.java (line 123) GC for ParNew: 221 ms for 1 collections, 3752290000 used; max is 6274678784 INFO [ScheduledTasks:1] 2012-06-17 19:52:37,230 GCInspector.java (line 123) GC for ConcurrentMarkSweep: 206 ms for 1 collections, 3752313400 used; max is 6274678784 INFO [ScheduledTasks:1] 2012-06-17 19:52:46,507 GCInspector.java (line 123) GC for ParNew: 243 ms for 1 collections, 3663162192 used; max is 6274678784 INFO [ScheduledTasks:1] 2012-06-17 19:52:54,510 GCInspector.java (line 123) GC for ParNew: 283 ms for 1 collections, 1582282248 used; max is 6274678784 INFO [ScheduledTasks:1] 2012-06-17 19:54:01,704 GCInspector.java (line 123) GC for ParNew: 235 ms for 1 collections, 1935534800 used; max is 6274678784 INFO [ScheduledTasks:1] 2012-06-17 19:55:13,747 GCInspector.java (line 123) GC for ParNew: 233 ms for 1 collections, 2356975504 used; max is 6274678784 INFO [ScheduledTasks:1] 2012-06-17 19:55:21,749 GCInspector.java (line 123) GC for ParNew: 264 ms for 1 collections, 2530976328 used; max is 6274678784 INFO [ScheduledTasks:1] 2012-06-17 19:55:29,794 GCInspector.java (line 123) GC for ParNew: 224 ms for 1 collections, 2592311336 used; max is 6274678784 BRs //Ares