Re: Unportable implementation of background worker start

On 2017-04-20 19:53:02 -0400, Tom Lane wrote:
> I wrote:
> > Andres Freund <andres(at)anarazel(dot)de> writes:
> >> On 2017-04-20 19:23:28 -0400, Tom Lane wrote:
> >>> or are the HANDLEs in a Windows WaitEventSet not inheritable
> >>> resources?
>
> >> So that kind of sounds like it should be doable.
>
> > Ah, good. I'll add a comment about that and press on.
>
> So ... what would you say to replacing epoll_create() with
> epoll_create1(EPOLL_CLOEXEC) ? Then a WaitEventSet would not
> represent inheritable-across-exec resources on any platform,
> making it a lot easier to deal with the EXEC_BACKEND case.
>
> AFAIK, both APIs are Linux-only, and epoll_create1() is not much
> newer than epoll_create(), so it seems like we'd not be giving up
> much portability if we insist on epoll_create1.

I'm generally quite in favor of using CLOEXEC as much as possible in our
tree. I'm a bit concerned with epoll_create1's availability tho - the
glibc support for it was introduced in 2.9, whereas epoll_create is in
2.3.2. On the other hand 2.9 was released 2008-11-13. If we remain
concerned we could just fcntl(fd, F_SETFD, FD_CLOEXEC) instead - that
should only be like three lines more code or such, and should be
available for a lot longer.

- Andres