Re: CVS commit: pkgsrc/lang/python26

[David Laight <david%l8s.co.uk@localhost>]

On Wed, Aug 15, 2012 at 09:02:58PM +0200, Matthias Drochner wrote:
> 
> On Wed, 15 Aug 2012 13:54:54 -0400
> Greg Troxel <gdt%ir.bbn.com@localhost> wrote:
> >   Log Message:
> >   as with python27: avoid POSIX semaphores on NetBSD, this is broken
> >   at least on -current
> > 
> > We've seen some flakiness that may be related to this (python26,
> > netbsd-6 from late March, i386).  Does anyone understand what's wrong,
> > and if any of the atf tests show it, and whether it's likely to be
> > wrong on netbsd-6?
> 
> I've seen problems with ipython. It seems that there is something
> in Python which closes all file descriptors >2 in a "for" loop,
> probably in the course of an "exec"...

That is quite common - even though the correct upper bound cannot
be determined (the rlimit value can be lower than an open fd).
It isn't clear that closeall() should affect them either.

If semaphores are using fds I'd worry about:
- use of low numbered fd, especially 0, 1 and 2 which can be closed.
- programs can allocate a lot of semaphores, using 1 fd for each
  will cause RLIMIT_NOFILE to be hit unexpectedly.
- one fd per semaphore seems like a lot of kernel resource.

Implementing them through a 'hidden' fd - I assume that is a separate
number space - doesn't have these issues.

        David

-- 
David Laight: david%l8s.co.uk@localhost