[Cbc] [FORGED] Re: Intermediate Results

[Stuart Mitchell]

Or indeed another option is running the software on Amazon EC2 where you
can rent a grunty machine (lots of memory) and have it run even when there
is no power where you are :-). Just make sure you use a client like
'screen' to make sure the optimisation continues when you are not connected.

Stu

On Tue, Jul 11, 2017 at 3:22 AM, acw at ascent.com <acw at ascent.com> wrote:

> Jeff, the CBC event handler absolutely has a callback that it calls
> whenever it finds a new best-so-far solution. You can fill in that callback
> to write out an MPS file, and then when you restart, you can read the saved
> solution and "hot-start" from it, or (almost as good) add a constraint that
> insists that the objective be at least as good as the one that was found
> earlier.
>
>
> From: Christopher Gross <christopher.gross at unikat.uni-augsburg.de>
> To: cbc at list.coin-or.org
> Date: 07/10/2017 10:52 AM
> Subject: Re: [Cbc] Intermediate Results
> ------------------------------
>
>
>
> Hi Jeff,
>
> being only an average C programmer myself and having looked at CBC code
> before, I would assume that storing and loading intermediate solution
> data will be quite a feat. Unfortunately, I can't give you any advice on
> that.
>
> However, I would suggest a different solution that works not only for
> CBC: Have you ever thought about getting an uninterrupted power supply
> (UPS)? Consumer units are available for less than 100USD and will last
> about 5-20 minutes, depending on the size of the device and your power
> consumption. If your power outages aren't longer than that, this should
> be sufficient to continue running your computations.
>
> If your power outages are longer than that, you could also consider
> running CBC in a virtual machine. Those can be paused and resumed at a
> later point in time. When the power goes out, your UPS will signal your
> guest system which will pause the virtual machine and shut down the
> system. You can then power it back up when the power is back on and
> resume the virtual machine, continuing your calculations.
>
> Hope that helps.
>
> Best regards,
>
> Christopher
>
> On 2017-07-10 15:49, Jeff Willert wrote:
> > I have recently started using CBC both standalone and through the PuLP
> > interface.  Some of my problems become rather large and take a
> > significant amount of time to run.  Unfortunately, I've been having
> > issues with computer reliability (power outages and such) and if the
> > optimization hasn't completed, I lose all of the progress which has been
> > made.
> >
> > Does CBC currently have the ability to write (to a file) the current
> > best solution at some interval, either in time or based on an iteration
> > count?  I've been looking at the source code but I am only a moderate C
> > programmer and haven't been able to find an easy way to do this.  I'm
> > happy to make changes to the code myself on my local copy if someone
> > could point me to the correct location.  Even an approximate solution is
> > better than losing all progress.
> >
> > Regards,
> > Jeff
> >
> >
> > _______________________________________________
> > Cbc mailing list
> > Cbc at list.coin-or.org
> > https://urldefense.proofpoint.com/v2/url?u=https-3A__list.
> coin-2Dor.org_mailman_listinfo_cbc&d=DwICAg&c=Ngd-
> ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=gEVaymfbiUvp55D10lWK6mFSIIFoSW
> nM41MvN3xiko6wjVENkHAS1IDcdpwngCCy&m=vU7ldw2G_FnOiwF6LzEqInJmI-
> c3LU0ZdJbjz2dLUtA&s=9h8XAYvraSGlKjFkU5k6pDTjF0_lUajzEXZKpbmXndw&e=
>
> >
>
> --
> Christopher Gross, M.Sc.
>
> Lehrstuhl für Health Care Operations/Health Information Management
>
> Universitäres Zentrum für Gesundheitswissenschaften am Klinikum Augsburg
> (UNIKA-T), Neusässer Straße 47, 86156 Augsburg;
>
> Wirtschaftswissenschaftliche Fakultät, Universität Augsburg,
> Universitätsstraße 16, 86159 Augsburg
>
>
> Tel.: +49 821 598-6452 <+49%20821%205986452>
>
> E-Mail:  christopher.gross at unikat.uni-augsburg.de
> Web:  https://urldefense.proofpoint.com/v2/url?u=http-
> 3A__www.unika-2Dt.de_&d=DwIGaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLx
> WPA_2Wlc4&r=UGItoAdbN76DIO86bdusOQ&m=h2okBq7QuhYOBOu_SO6GMhp38YAi-_
> 8am9cv4MIxkdI&s=bgspdUjsrozmDWtHwUipNFw1dn1yofHex5GvrQU3tLE&e=
> _______________________________________________
> Cbc mailing list
> Cbc at list.coin-or.org
> https://urldefense.proofpoint.com/v2/url?u=https-3A__list.
> coin-2Dor.org_mailman_listinfo_cbc&d=DwIGaQ&c=Ngd-
> ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=UGItoAdbN76DIO86bdusOQ&m=
> h2okBq7QuhYOBOu_SO6GMhp38YAi-_8am9cv4MIxkdI&s=ty2FrXQdupLpHRwSISjxh_
> Bl47e8rhai98aeLk8NPoY&e=
>
>


-- 
Stuart Mitchell
PhD Engineering Science
Extraordinary Freelance Programmer and Optimisation Guru
www.stuartmitchell.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://list.coin-or.org/pipermail/cbc/attachments/20170711/a62eff7f/attachment.html>