Re: walsender bug: stuck during shutdown

On 2020-Nov-25, Fujii Masao wrote:

> But whether MyWalSnd->write is InvalidRecPtr or not, if it's behind sentPtr,
> walsender should keep waiting for the ack to all the sent message to be
> replied, i.e., isn't this expected behavior of normal shutdown? That is,
> if we want to shutdown walsender even when the client side doesn't
> reply message, immediate shutdown should be used or the client side
> should be terminated, instead?

I don't think "waiting forever" can be considered the expected behavior;
this has caused what are nominally production outages several times
already, since we sent a shutdown signal to the server and it never
completed shutting down.

If you want to propose a better patch to address the issue, feel free,
but keeping things as they are seems a bad idea to me.

(Hmm, maybe another idea would be to have WalSndDone cause a keepalive
message to be sent to the client and complete shut down when we get a
reply to that.)