Xref: utzoo comp.unix.wizards:14463 comp.unix.xenix:4740
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!ucsd!rutgers!bellcore!faline!thumper!ulysses!andante!alice!debra
From: debra@alice.UUCP (Paul De Bra)
Newsgroups: comp.unix.wizards,comp.unix.xenix
Subject: Re: pid rollover?
Message-ID: <8857@alice.UUCP>
Date: 1 Feb 89 20:44:43 GMT
References: <460@oglvee.UUCP> <1989Jan31.164710.19502@ateng.ateng.com>
Reply-To: debra@alice.UUCP ()
Organization: AT&T, Bell Labs
Lines: 22

In article <1989Jan31.164710.19502@ateng.ateng.com> chip@ateng.ateng.com (Chip Salzenberg) writes:
}According to jr@oglvee.UUCP (Jim Rosenberg):
}>Our system is an Altos 2000 running Xenix System V.  The CPU is a 386, and
}>the C compiler produces 4 as sizeof(int).  However we seem to be hitting
}>rollover of pids at 32K, implying that the kernel must be using short as the
}>type of a pid -- at least internally.
}
}The getpid() system call has to work for '286 binaries under Xenix/386.
}So all pids must be representable as a 16-bit integers.

This is not the reason at all. The limit on pid's is 30000, which is just
an arbitrary number, for historical reasons, and which appears to be the
same on all Unix systems (at least all I've seen). It probably is smaller than
32767 because Unix originally ran on 16-bit machines (PDP), but the number
is just arbitrary. Any number greater than the maximal number of processes
would do.

Paul.
-- 
------------------------------------------------------
|debra@research.att.com   | uunet!research!debra     |
------------------------------------------------------