Bizarre Compaction Manager Behaviour
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Key: CASSANDRA-3484
URL: https://issues.apache.org/jira/browse/CASSANDRA-3484
Project: Cassandra
Issue Type: Bug
Components: Core
Affects Versions: 1.0.2
Environment: RHEL 6
java version "1.6.0_26"
6 node cluster (5 nodes 0.8.6, 1 node 1.0.2 minus CASSANDRA-2503)
Reporter: Dan Hendry
It seems the CompactionManager has gotten itself into a bad state. My 1.0.2
node has been up for 20 hours now - checking via JMX, the compaction manager is
reporting that it has completed 14,797,412,000 tasks. Yep, thats right 14
billion tasks and increasing at a rate of roughly 208,400/second.
I should point out that I am currently running a major compaction on the node.
My theory is that this problem was introduced by CASSANDRA-3363. It looks like
SizeTieredCompactionStrategy.getBackgroundTasks() returns a set of task without
consideration for any in-progress compactions. Compactions are only kicked off
if task.markSSTablesForCompaction() returns true (CompactionManager line 127)
but the task resubmission is based only on the task list not being empty
(CompactionManager line 141). Should the logic not be to only reschedule if a
task has actually been executed?
I am just waiting now for the major compaction to finish to see if the problem
goes away as would be suggested by my theory.
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