Summary

Confluence Performance degrades drastically with time due to many long-running tasks created by the page creator app.

Environment

Confluence server or Data Center version 7.4.3

Diagnosis

Reviewing the GC logs, the throughput of the application decreases with time and after a few days, the throughput reduces to even below 80%. During this time, if there are any requests that are memory intensive, then that will further deteriorate the application performance and some users may experience 503 error responses. 

Once the heap dump is captured, we can then see that there are many long-running tasks associated with the page creator app which are consuming a lot of memory. These tasks never seem to be complete and this memory usage by long-running tasks increases with time.  

Cause

This issue appears when there are multiple instantiations of large templates (400 pages) that are executed in parallel on the same source space/target space. Due to these templates, it triggers a long-running task in the background and even though the request completes, these tasks still hold resources and occupy a lot of memory. With time, the memory consumption of these tasks is so large that it starts degrading the performance of Confluence as other requests are starving for memory.  

Solution

This issue has been fixed under the Page Tree Creator plugin version 8.2.14 and above. If you are experiencing performance issues due to the Page Tree Creator app, then upgrade to version 8.2.14 or above and see if that helps.