<font size=2 face="sans-serif">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.</font>
<br>
<br>
<br>
<table width=100%>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">From:</font>
<td><font size=1 face="sans-serif">Christopher Gross <christopher.gross@unikat.uni-augsburg.de></font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">To:</font>
<td><font size=1 face="sans-serif">cbc@list.coin-or.org</font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">Date:</font>
<td><font size=1 face="sans-serif">07/10/2017 10:52 AM</font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">Subject:</font>
<td><font size=1 face="sans-serif">Re: [Cbc] Intermediate Results</font></table>
<br>
<hr noshade>
<br>
<br>
<br><tt><font size=2>Hi Jeff,<br>
<br>
being only an average C programmer myself and having looked at CBC code
<br>
before, I would assume that storing and loading intermediate solution <br>
data will be quite a feat. Unfortunately, I can't give you any advice on
<br>
that.<br>
<br>
However, I would suggest a different solution that works not only for <br>
CBC: Have you ever thought about getting an uninterrupted power supply
<br>
(UPS)? Consumer units are available for less than 100USD and will last
<br>
about 5-20 minutes, depending on the size of the device and your power
<br>
consumption. If your power outages aren't longer than that, this should
<br>
be sufficient to continue running your computations.<br>
<br>
If your power outages are longer than that, you could also consider <br>
running CBC in a virtual machine. Those can be paused and resumed at a
<br>
later point in time. When the power goes out, your UPS will signal your
<br>
guest system which will pause the virtual machine and shut down the <br>
system. You can then power it back up when the power is back on and <br>
resume the virtual machine, continuing your calculations.<br>
<br>
Hope that helps.<br>
<br>
Best regards,<br>
<br>
Christopher<br>
<br>
On 2017-07-10 15:49, Jeff Willert wrote:<br>
> I have recently started using CBC both standalone and through the
PuLP <br>
> interface. Some of my problems become rather large and take
a <br>
> significant amount of time to run. Unfortunately, I've been
having <br>
> issues with computer reliability (power outages and such) and if the
<br>
> optimization hasn't completed, I lose all of the progress which has
been <br>
> made.<br>
> <br>
> Does CBC currently have the ability to write (to a file) the current
<br>
> best solution at some interval, either in time or based on an iteration
<br>
> count? I've been looking at the source code but I am only a
moderate C <br>
> programmer and haven't been able to find an easy way to do this. I'm
<br>
> happy to make changes to the code myself on my local copy if someone
<br>
> could point me to the correct location. Even an approximate
solution is <br>
> better than losing all progress.<br>
> <br>
> Regards,<br>
> Jeff<br>
> <br>
> <br>
> _______________________________________________<br>
> Cbc mailing list<br>
> Cbc@list.coin-or.org<br>
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<br>
-- <br>
Christopher Gross, M.Sc.<br>
<br>
Lehrstuhl für Health Care Operations/Health Information Management<br>
<br>
Universitäres Zentrum für Gesundheitswissenschaften am Klinikum Augsburg<br>
(UNIKA-T), Neusässer Straße 47, 86156 Augsburg;<br>
<br>
Wirtschaftswissenschaftliche Fakultät, Universität Augsburg,<br>
Universitätsstraße 16, 86159 Augsburg<br>
<br>
<br>
Tel.: +49 821 598-6452<br>
<br>
E-Mail: christopher.gross@unikat.uni-augsburg.de<br>
Web: </font></tt><a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__www.unika-2Dt.de_&d=DwIGaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=UGItoAdbN76DIO86bdusOQ&m=h2okBq7QuhYOBOu_SO6GMhp38YAi-_8am9cv4MIxkdI&s=bgspdUjsrozmDWtHwUipNFw1dn1yofHex5GvrQU3tLE&e="><tt><font size=2>https://urldefense.proofpoint.com/v2/url?u=http-3A__www.unika-2Dt.de_&d=DwIGaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=UGItoAdbN76DIO86bdusOQ&m=h2okBq7QuhYOBOu_SO6GMhp38YAi-_8am9cv4MIxkdI&s=bgspdUjsrozmDWtHwUipNFw1dn1yofHex5GvrQU3tLE&e=</font></tt></a><tt><font size=2>
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