https://bugs.openldap.org/show_bug.cgi?id=9631
--- Comment #2 from HAMANO Tsukasa hamano@osstech.co.jp --- Our environment use static linked slapd with backend and libwiredtiger, so we were not aware the issue.
The reason is obvious: dlclose() makes crash when shared code is running in the other thread. I had omitted the cache DB closing, so the module unload was called while the shared code was still running. This fix will ensure terminating all threads when module unload. https://git.openldap.org/openldap/openldap/-/merge_requests/395