Re: Keepalive for max_standby_delay

Heikki Linnakangas wrote:
> Simon Riggs wrote:
>> WALSender sleeps even when it might have more WAL to send, it doesn't
>> check it just unconditionally sleeps. At least WALReceiver loops until
>> it has no more to receive. I just can't imagine why that's useful
>> behaviour.
> 
> Good catch. That should be fixed.
> 
> I also note that walsender doesn't respond to signals, while it's
> sending a large batch. That's analogous to the issue that was addressed
> recently in the archiver process.

Attached patch rearranges the walsender loops slightly to fix the above.
XLogSend() now only sends up to MAX_SEND_SIZE bytes (== XLOG_SEG_SIZE /
2) in one round and returns to the main loop after that even if there's
unsent WAL, and the main loop no longer sleeps if there's unsent WAL.
That way the main loop gets to respond to signals quickly, and we also
get to update the shared memory status and PS display more often when
there's a lot of catching up to do.

Comments, have I screwed up anything?

-- 
  Heikki Linnakangas
  EnterpriseDB   http://www.enterprisedb.com