Re: Parallel query hangs after a smart shutdown is issued

On Thu, Aug 13, 2020 at 2:37 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> I experimented with separating the shutdown-in-progress state into a
> separate variable, letting us actually reduce not increase the number of
> pmStates. This way, PM_RUN and other states still apply until we're
> ready to pull the shutdown trigger, so that we don't need to complicate
> state-based decisions about launching auxiliary processes. This patch
> also unifies the signal-sending for the smart and fast shutdown paths,
> which seems like a nice improvement. I kind of like this, though I'm not
> in love with the particular variable name I used here (smartShutState).

Makes sense. I tested this version on a primary and a replica and
verified that parallel workers launch, but I saw that autovacuum
workers still can't start without something like this:

@@ -2463,7 +2463,8 @@ canAcceptConnections(int backend_type)
* be returned until we have checked for too many children.
*/
if (smartShutState != SMART_NORMAL_USAGE &&
- backend_type != BACKEND_TYPE_BGWORKER)
+ backend_type != BACKEND_TYPE_BGWORKER &&
+ backend_type != BACKEND_TYPE_AUTOVAC)
{
if (smartShutState == SMART_SUPERUSER_ONLY)
result = CAC_WAITBACKUP; /* allow
superusers only */
@@ -2471,7 +2472,8 @@ canAcceptConnections(int backend_type)
return CAC_SHUTDOWN; /* shutdown is pending */
}
if (pmState != PM_RUN &&
- backend_type != BACKEND_TYPE_BGWORKER)
+ backend_type != BACKEND_TYPE_BGWORKER &&
+ backend_type != BACKEND_TYPE_AUTOVAC)
{
if (Shutdown > NoShutdown)
return CAC_SHUTDOWN; /* shutdown is pending */