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From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.unix.wizards
Subject: Re: Checkpoint/Restart (was "no subject - file transmission")
Message-ID: <13611@smoke.BRL.MIL>
Date: 17 Aug 90 19:08:48 GMT
References: <24193@adm.BRL.MIL>
Organization: U.S. Army Ballistic Research Laboratory, APG, MD.
Lines: 26

In article <24193@adm.BRL.MIL> mwm@decwrl.dec.com (Mike) writes:
>>> > I need a tool that would stop a running process and let it be
>>> > restarted at a later date.
>>> Seriously, doing this in any substantive manner is difficult and I'm sure
>>> it would be virtually impossible to bullet-proof it on UNIX.
>Yes - but you don't need it bullet-proofed; you just need it to work
>most of the time. After all, being able to restart 90% of the time is
>much better than being able to restart 0% of the time. Other OSs
>provide this facility (or similar ones) in the face of these
>difficulties; Unix ought to be able to.

Other operating systems do not have the rich process environment
that UNIX provides.  If there are only a small number of things that
need to be straightened out in a batch-processing environment, then
system-provided checkpointing is feasible.

>Why does this line come to mind: "Do the easy 90% and give it to the
>users; do the hard 10% only if they then ask for it."

Why does the thought come to mind "anyone whose application requires
only a 90% chance of executing successfully shouldn't be using the
computer at all"?

Any application that is EXPECTED to run for a long time should have
interruptibility features built into it.  I did this back in 1967,
and have little sympathy for people who are too lazy to deal with it.