If multiple users access the same task record at once, there can be performance issues when building the history set for the activity stream. History sets are not allowed to be built concurrently, so one can block all other threads, and in some scenarios lead to semaphore exhaustion on all nodes.
Steps to Reproduce
1. Create an incident with a large amount of history in the activity stream.
2. Have hundreds of users open the incident at the same time.
3. Transactions will get stuck waiting on a mutext while the first transaction builds the history set.
This issue has been fixed in Istanbul Patch 10+, Jakarta Patch 3+, Kingston and later releases. Please review the Fixed In section to determine the latest available patch your instance can be upgraded to.
Related Problem: PRB1039322