Manual:$wgCriticalSectionTimeLimit

Details
The maximum time critical sections are allowed to stay open. Critical sections are used to defer Excimer request timeouts. If Excimer is available and this time limit is exceeded, an exception will be thrown at the next opportunity, typically after a long-running function like a DB query returns.

Critical sections may wrap long-running queries, and it's generally better for the timeout to be handled a few milliseconds later when the critical section exits, so this should be a large number.

This limit is ignored in command-line mode.