On Honolulu Maintenance release, we have tried service instantiation using Macro Flow 60-70 times. We did this on two different ONAP clusters. On both installations, we faced an issue with SDNC after some time and the service instantiation flow starts failing after the 60-70th run.
Note: We are instantiating CNFs not VNFs, but not sure if that is related to this error.

After the 60-70th run, SDNC starts throwing this error:

Transaction member-1-datastore-config-fe-0-txn-2140-0 changing state from CAN_COMMIT_PENDING to FAILED
2021-10-21T14:23:08.533Z||ispatcher-329115|DEBUG|Shard                           |316 - org.opendaylight.controller.sal-clustering-commons - 2.0.6|member-1-shard-default-config: An exception occurred during canCommit for member-1-datastore-config-fe-0-txn-2140-0
org.opendaylight.mdsal.common.api.OptimisticLockFailedException: Optimistic lock failed for path /(org:onap:sdnc:northbound:generic-resource?revision=2017-08-24)services/service/service[{(org:onap:sdnc:northbound:generic-resource?revision=2017-08-24)service-instance-id=1cc18ce5-5755-413b-906e-6d4b7a09891c}]

The entire logs are attached, error occurs at timestamp: 2021-10-21T14:23:08.533Z||ispatcher-329115|DEBUG|Shard

We can no longer successfully instantiate due to this error.
The solution we found was to restart the SDNC pod, which apparently releases the locks.
( But on doing this, we lose information, and the service models have to be redistributed, so it is not the best solution)