Re: Terminating a backend

Tom Lane wrote:
> Bruce Momjian <bruce@momjian.us> writes:
> > Bruce Momjian wrote:
> >> When we get the termination signal, why can't we just set a global
> >> boolean, do a query cancel, and in the setjmp() code block check the
> >> global and exit --- at that stage we know we have released all locks and
> >> can exit cleanly.
> 
> > Should I add this as a TODO?  Seems so.  Tom commented in the patches
> > queue that it will not work but I don't understand why.
> 
> The problem with treating it like elog(ERROR) is that you're at the
> mercy of user-defined code as to whether you'll actually exit or not.
> UDFs can trap elog(ERROR).

Well, we can punt and blame the writer of the UDF if the signal is not
timely honored.  Having something that works for 98% of the cases, can
be fixed for 1% of the remainder, and only fails in 1% (proprietary code
that cannot be fixed) is better than having nothing at all.

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support