We conducted stress testing for the patch with a setup of one primary
node with 100 tables and five subscribers, each having 20
subscriptions. Then created three physical standbys syncing the
logical replication slots from the primary node.
All 100 slots were successfully synced on all three standbys. We then
ran the load and monitored LSN convergence using the prescribed SQL
checks.
Once the standbys were failover-ready, we were able to successfully
promote one of the standbys and all the subscribers seamlessly
migrated to the new primary node.
We replicated the tests with 200 tables, creating 200 logical
replication slots. With the increased load, all the tests were
completed successfully.
Minor errors (not due to patch) observed during tests -
1) When the load was run, on subscribers, the logical replication
apply workers started failing due to timeout. This is not related to
the patch as it happened due to the small "wal_receiver_timeout"
setting w.r.t. the load. To confirm, we ran the same load without the
patch too, and the same failure happened.
2) There was a buffer overflow exception on the primary node with the
'200 replication slots' case. It was not related to the patch as it
was due to short memory configuration.
All the tests were done on Windows as well as Linux environments.
Thank you Ajin for the stress test and analysis on Linux.