Re: [path][rfc] add PR_DETACH prctl command

[Stas Sergeev <stsp@aknet.ru>]

08.04.2011 22:13, Bryan Donlan wrote:
> I can't comment on the patch itself, but, if your application knows it
> might have to daemonize after spinning up threads, why not simply
> fork() immediately on startup, and have the parent simply wait forever
> for either the child to die or for a daemonize signal from the child?
> If done early enough it shouldn't tie up too much memory, and it
> wouldn't require any of these invasive kernel changes. As an added
> bonus, it's portable to all unixen :)
Yes, thats almost always true. Except when you deal with
the vendor-provided poorly-coded drivers and libs, where
you get the drivers initialized only via the lib. And the
initialization process must be finished before the boot-up
can continue, but that's not the whole story: only the
process that initialized that lib, can then work with it.
And of course that lib creates a dozen of threads...
OK, you've got the idea. :)
But anyway. Yes, not everyone have to deal with such a
nightmare, this is very rare. But people being confused
by the fact that daemon() silently loses threads, are not
rare. So I just wonder: even if the workaround is simple,
why searching for the workaround at all? If you need
2 syscalls to detach from parent, and you loose the threads
in a process, then why not to have a single call, that
detaches without loosing threads?
But in any case, I am mostly inclinced to leave that patch
for my project only.