Performance impact due to index optimization
Confluence experiences slow performance at regular intervals. Thread dumps, taken across time, show this thread:
... at $Proxy29.optimizeIndex(Unknown Source) at com.atlassian.confluence.search.lucene.IndexOptimizer.executeJob(IndexOptimizer.java:20) at com.atlassian.confluence.setup.quartz.AbstractClusterAwareQuartzJobBean.surroundJobExecutionWithLogging(AbstractClusterAwareQuartzJobBean.java:64) at com.atlassian.confluence.setup.quartz.AbstractClusterAwareQuartzJobBean.executeInternal(AbstractClusterAwareQuartzJobBean.java:47) ...
The index optimization job is running and causing a backlog.
Add debug level logging for the following class:
Watch at 03:00:00 and 15:00:00 for these threads. If you're noticing long delays until the next DEBUG level instance of this class, it may be a culprit.
Alternatively, watch for the thread above in your thread dumps.
By default, the indexOptimizerTrigger is set to run at 3am and 3pm daily. Configure the index optimization to run once a week, or less often.