I've an open ticket with the support for the same issue, but havent heard back from them yet. The engine is still up and running, and the issue doesnt seem to be effecting anything. What version is your siem at?
The fix is in the most recent maintenance release, which was released to support. You can open a case and have them send you the MR. This is the information from the release notes on bugs that were addressed. The issue is actually related to real-time alarming and not the correlation engine, which is why the correlation engine continues to work
• 1018395 - "Could not send event(s) to correlator through socket - Unable to obtain lock(4)" error in messages