OS: Amazon Linux AMI release 2015.03
JVM: Java HotSpot(TM) 64-Bit Server VM (25.40-b25, mixed mode)
Java: version 1.8.0_40, vendor Oracle Corporation
CPU: 8 core Intel(R) Xeon(R) CPU E5-2670 v2 @ 2.50GHz
Yesterday I upgraded my Cassandra cluster from 2.0.14 to 2.0.16, after upgrade, I am start seeing some strange behaviours of "PendingTasks" reporting.
The Cassandra repository I am using is datastax, steps I performed for upgrade:
yum update -y cassandra20
The upgrade went fine, after upgrade cluster is operating okay. "nodetool info and nodetool status" results looked fine. "nodetool version" is reporting the correct version.
But our monitoring system start reporting some crazy "pendingtasks". For example, "pending taks" for node1 sometimes jump from 0 to 15K for about 1 minute, then drop back to 0. This issue keeps occurring, didn't have this issue with 2.0.14. Our monitoring system is checking the value of "MBeans" -> "CompactionManager" -> "PendingTasks".