RE: Resetting synchronous_standby_names can wait for CHECKPOINT to finish

Hello,

> When the checkpointer process is busy, even if we reset synchronous_standby_names, the resumption of the backend processes waiting in SyncRep are made to wait until the checkpoint is completed.
> This prevents the prompt resumption of application processing when a problem occurs on the standby server in a synchronous replication system.
> I confirmed this in PostgreSQL 12.18.

I have tested this issue on Postgres built from the master branch (17devel) and observed the same behavior where the backend SyncRep release is blocked until CHECKPOINT completion.

In situations where a synchronous standby instance encounters an error and needs to be detached, I believe that the current behavior of waiting for SyncRep is inappropriate as it delays the backend.
I don't think changing the position of SIGHUP processing in the Checkpointer process carries much risk. Is there any oversight in my perception?

Regards,
Yusuke Egashira.