Hello! I've noticed a strange CPU utilisation patterns on machines in our cluster. After C* daemon restart it behaves in a normal way, after a few weeks since a restart CPU usage starts to raise. Currently on one of the nodes (screenshots attached) cpu load is ~4. Shortly before restart load raises to ~15 (our cassandra machines have 16 cpus).
In that cluster we're using bulkloading from hadoop cluster with 1400 reducers (200 parallel bulkloading tasks). After such session of heavy bulkloading number of pending compactions is quite high but it's able to clear them before next "bulkloading session". We're also tracking number of pending compactions and during most of the time it's 0. On our machines we do have a few gigs of free memory ~7GB (17GB used), also it seems like we aren't IO bound. Screenshots from our zabbix with CPU utilisation graphs: http://i60.tinypic.com/xas8q8.jpg http://i58.tinypic.com/24pifcy.jpg Do you guys know what could be causing such high load? -- mp
