Issue Description

This issue was originally opened against DS https://pagure.io/389-ds-base/issue/49219. It is a bug in schema-compat locking mechanism, so this bug is opened as a clone of it.

When deleting a user, deadlock occures "sometimes". Only a restart of dirsrv resolve the problem.
I say "sometimes" because it is not then only condition of the bug : most delete operations are successful.

Package Version and Platform

Centos 7.3
389-ds-base-libs-1.3.5.10-18.el7_3.x86_64
389-ds-base-snmp-1.3.5.10-18.el7_3.x86_64
389-ds-base-debuginfo-1.3.5.10-18.el7_3.x86_64
389-ds-base-1.3.5.10-18.el7_3.x86_64
Steps to reproduce

I haven't achieved a deterministic way to reproduce this bug. I have only determined what is the minimal context of the bug. I miss a element I think. So someone can considers that necessary but not sufficient conditions

Delete a user : the operation can be time expensive because of memberOf Plugin and Managed Entry plugin
Some LDAP ABANDON of LDAP search.
SASL/GSSAPI connection of a replica : that is the last access log before deadlock

One time it occurs when adding a user

Actual results

deadlock when deleting user

Expected results

no deadlock when deleting occurs