Performance impact due to index optimization

Platform Notice: Data Center Only - This article only applies to Atlassian products on the Data Center platform.

Note that this KB was created for the Data Center version of the product. Data Center KBs for non-Data-Center-specific features may also work for Server versions of the product, however they have not been tested. Support for Server* products ended on February 15th 2024. If you are running a Server product, you can visit the Atlassian Server end of support announcement to review your migration options.

*Except Fisheye and Crucible

Symptoms

Confluence experiences slow performance at regular intervals. Generating a Thread Dump, taken across time, show this thread:

1 2 3 4 5 6 ... 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) ...

Cause

The index optimization job is running and causing a backlog.

Diagnosis

Configuring Logging for the following class:

1 confluence.search.lucene.DefaultConfluenceIndexManager

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.

Resolution

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.

Updated on April 2, 2025

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