Re: PID sequences

Joseph H. Buehler (
26 Feb 1998 21:59:54 -0500

Chris Wedgwood <> writes:

> Anyhow... I assume they are using rc4 so assuming the initial state is kept
> secret these should be fairly hard to guess - only, it doesn't satisfy
> Dean's desired criterion that no PID be re-used within a short amount of
> time.
> Especially since we only have 15 bit PIDs available. Now, if we fork like
> crazy we can burn a few thousand of these in a fairly short amount of time,
> making a check the last n PIDs system too expensive, so statistically re-use
> of a number could be made occur if one desired.

AIX has non-sequential pids. If it helps any, I believe that part of
the pid is the slot number in the process table.

Joe Buehler

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