We used following to get the number of rwlocks for /usr/sbin/ns-slapd process in Centos 7.9 to catch deadlocks:

PID=`pidof ns-slapd`

gdb -ex 'set confirm off' -ex 'set pagination off' -ex 'thread apply all bt full' -ex 'quit' /usr/sbin/ns-slapd $PID |& grep '^#0.*lock' | grep pthread_rwlock | sort -u

That helped us to detect ns-slapd hang caused by deadlocks.

After migrating to Red Hat 8.6, we had a lot of hangs (dirsvr is running but not responding) and could not find why. We use the same above method, however, we are not able to catch anything. I wonder if there is a different way to count the rwlocks in Red Hat 8.6?

We realize that there are multiple reasons to cause hangs, however, we would like to rule out the possibility of the deadlock.

The OS and packages:

Red Hat Enterprise Linux release 8.6 (Ootpa)

ipa-server.x86_64 4.9.8-7.module+el8.6.0+14337+19b76db2 @rhel-8-for-x86_64-appstream-rpms

slapi-nis-0.56.6-4.module+el8.6.0+12936+736896b2.x86_64

389-ds-base-libs-1.4.3.28-6.module+el8.6.0+14129+983ceada.x86_64

389-ds-base-1.4.3.28-6.module+el8.6.0+14129+983ceada.x86_64