Re: Apparent walsender bug triggered by logical replication

Hi,

On 2017-06-29 20:07:14 -0400, Tom Lane wrote:
> I was able to make the hang go away by means of the attached patch that
> allows WalSndWaitForWal to exit early if the client has shut down the
> COPY. However, since that function is miserably underdocumented (like
> most of this code :-(), I have little idea if this is correct or safe.

Seems reasonable to me.

> I also wonder why WalSndWaitForWal is being called for WAL that seemingly
> doesn't exist yet, and whether that doesn't indicate another bug somewhere
> in this stack.

That's pretty normal - we can only send back something once a
transaction is complete, and until that happens we'll just block waiting
for more WAL.

Greetings,

Andres Freund