Re: insert performance for win32

> "Merlin Moncure" <merlin(dot)moncure(at)rcsonline(dot)com> writes:
> > Nailed it.
>
> > problem is in mainloop.c -> setup_cancel_handler. Apparently you
can
> > have multiple handlers and windows keeps track of them all, even if
they
> > do the same thing. Keeping track of so many system handles would
> > naturally slow the whole process down.
>
> Yipes. So we really want to do that only once.
>
> AFAICS it is appropriate to move the sigsetjmp and
setup_cancel_handler
> calls in front of the per-line loop inside MainLoop --- can anyone see
> a reason not to?

hm. mainloop is re-entrant, right? That means each \i would reset the
handler...what is downside to keeping global flag?

> I'm inclined to treat this as an outright bug, not just a minor
certainly...

> performance issue, because it implies that a sufficiently long psql
> script would probably crash a Windows machine.

actually, it's worse than that, it's more of a dos on the whole system,
as windows will eventually stop granting handles, but there is a good
chance of side effects on other applications.

Merlin

"Merlin Moncure" <merlin(dot)moncure(at)rcsonline(dot)com> writes:
>> AFAICS it is appropriate to move the sigsetjmp and
>> setup_cancel_handler
>> calls in front of the per-line loop inside MainLoop --- can anyone see
>> a reason not to?

> hm. mainloop is re-entrant, right? That means each \i would reset the
> handler...what is downside to keeping global flag?

Ah, right, and in fact I'd missed the comment at line 325 pointing out
that we're relying on the sigsetjmp to be re-executed every time
through. That could be improved on, likely, but not right before a
release.

Does the flag need to be global? I'm thinking

void
setup_cancel_handler(void)
{
+ static bool done = false;
+
+ if (!done)
SetConsoleCtrlHandler(consoleHandler, TRUE);
+ done = true;
}

regards, tom lane