Re: Hot Standy introduced problem with query cancel behavior

Andres Freund <andres(at)anarazel(dot)de> writes:
> Stupid question:

> Why dont we add CHECK_FOR_INTERRUPTS (or something similar) to everything
> calling recv (especially in the EINTR) case?

We pretty much have CHECK_FOR_INTERRUPTS everywhere that it's safe
already. The problem here is not a lack of execution of
CHECK_FOR_INTERRUPTS, but what to do inside it. Although I pointed to
an interrupt service routine as being the worst case, the fact is that
Simon's code will crash the system in a large number of scenarios even
when ProcessInterrupts is called from CHECK_FOR_INTERRUPTS rather than
directly from the signal handler. You can't just abort transactions and
then return to a nest of functions that think they still have a live
transaction they can resume. This is why the standard error code path
has the AbortTransaction call out in the sigjmp catcher, not inside
elog() itself.

regards, tom lane