Greg Sabino Mullane <htamfids@gmail.com> writes:
> Good question. Forking is expensive, and there is also a lot of
> housekeeping associated with it that is simply not needed here. We want
> this to be lightweight, and simple. No need to fork if we are just going to
> do a few strncmp() calls and a send().
send() can block. I think calling it in the postmaster is a
nonstarter. For comparison, we make an effort to not do any
communication with incoming clients until after forking a child
to do the communication. The one exception is if we have to
report fork failure --- but we don't make any strong guarantees
about that report succeeding. (IIRC, we put the port into nonblock
mode and try only once.) That's probably not a behavior you want
to adopt for non-edge-case usages.
Another point is that you'll recall that there's a lot of
interest in switching to a threaded model. The argument that
"fork is too expensive" may not have a long shelf life.
I'm not taking a position on whether $SUBJECT is a good idea
in the first place.
regards, tom lane
