Re: [HACKERS] Function to kill backend

Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> I have applied the attached patch:
> Exit backend from SIGTERM or FATAL by simulating client EOF, rather than
> calling proc_exit() directly. This should make SIGTERM more reliable.

After further consideration I have concluded that this was a
spectacularly bad idea and we should revert that patch. There is a very
large amount of processing that this patch will cause to happen after a
FATAL error has been declared, and I doubt that any of it is a good
idea. Some examples:

* AbortCurrentTransaction() --- not too cool if the FATAL error was one
of the ones in xact.c that are complaining of fatally bollixed
transaction state.

* pgstat reporting --- aside from the chance of an outright crash, we
might be transmitting bogus statistics to the collector.

* sending a ReadyForQuery (Z) message --- one thing we quite certainly
ain't is ReadyForQuery.

* EnableNotifyInterrupt --- this may result in actually trying to run
a transaction to look through pg_listener :-(

* ProcessConfigFile, if we had a pending SIGHUP --- also not too cool,
if the FATAL was from guc.c.

I am still dubious that zapping random backends with SIGTERM is a sane
or supportable idea. But this patch does not make things better, it
simply greatly increases the chance of a FATAL exit turning into a
backend crash or PANIC.

regards, tom lane