Re: putting a bgworker to rest

On 2013-04-23 14:11:26 -0300, Alvaro Herrera wrote:
> Andres Freund wrote:
> > On 2013-04-23 11:59:43 -0300, Alvaro Herrera wrote:
> > > Andres Freund wrote:
> > > > Hi all,
> > > > 
> > > > I noticed the need to simply stop a bgworker after its work is done but
> > > > still have it restart in unusual circumstances like a crash.
> > > > Obviously I can just have it enter a loop where it checks its latch and
> > > > such, but that seems a bit pointless.
> > > > 
> > > > Would it make sense to add an extra return value or such for that?
> > > 
> > > KaiGai also requested some more flexibility in the stop timing and
> > > shutdown sequence.  I understand the current design that workers are
> > > always on can be a bit annoying.
> > > 
> > > How would postmaster know when to restart a worker that stopped?
> > 
> > I had imagined we would assign some return codes special
> > meaning. Currently 0 basically means "restart immediately", 1 means
> > "crashed, wait for some time", everything else results in a postmaster
> > restart. It seems we can just assign returncode 2 as "done", probably
> > with some enum or such hiding the numbers.
> 
> So a "done" worker would never be restarted, until postmaster sees a
> crash or is itself restarted?  I guess that'd be useful for workers
> running during recovery, which terminate when recovery completes.  Is
> that your use case?

Well, its not actual postgres recovery, but something similar in the
context of logical replication.

Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
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