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Re: Fwd: Which 90% of POSIX /is/ good then?

From: Jonathan S. Shapiro
Subject: Re: Fwd: Which 90% of POSIX /is/ good then?
Date: Thu, 27 Oct 2005 10:54:48 -0400

On Thu, 2005-10-27 at 12:12 +0100, Brian Brunswick wrote:
> On 27/10/05, Alfred M. Szmidt <address@hidden> wrote:
> >    * pids are broken. They aren't persistent handles, like fds, so
> >    hello race conditions on anything using them.
> >
> > You cannot get away from race conditions, nor should pids be persitent
> > in a non-persitent system.  In other words, PID's aren't broken.
> By persistent, I mean on the the short term. You have absolutely /no
> guarantee/ that the process you send a signal to is actually the same
> one you just collected the pid for. They get re-used quite fast. They
> should be like file handles instead, always referring to the same
> object.

PLEASE can we avoid the term "persistent" for this? It will be terribly
confusing. I suggest that a better word might be "durable". What you
seem to want is some replacement for a PID that has the property that
(a) as long at it exists, it is bound to the same process, and (b) it
isn't reused.

Hmm. Sounds like a process capability!

Pids are also broken for another reason: they are public entries in a
globally shared, mutable namespace.


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