Galera 4 and MySQL 8 replica_parallel_workers parameter

[Qusay Thiab]

We are facing issue with Galera 4 and MySQL 8 with replica_parallel_workers default setting is set to 4, is there a need to set this to 1 (i.e. single threaded) ?? as we faced issues with queries stuck in this state: waiting for handler

[Seppo Jaakola]

MySQL 8.0.32 has indeed replica_parallel_workers = 4 by default, and it has turned out that this can cause async replication thread hanging. This issue is fixed in next 8.0.33 version, which is in final release preparation stage atm. With older MySQL versions, the work-around will be to make sure that set replica_parallel_workers = 1 

[Qusay Thiab]

Thanks for confirming the issue and the solution ... we will test it and see ...

[Colin Charles]

just to let you know, there is a new release, please give it a go

https://galeracluster.com/2023/06/galera-cluster-for-mysql-5-7-42-and-mysql-8-0-33-released/