[Cbc] Cbc segfault after many hours of CPU time

[acw at ascent.com]

Thank you for your prompt attention! I believe it is close to trunk 
stable; I did my build from the recommended stable sources on February 1, 
so if there have been relevant changes I guess I should rebuild and retry.

In the meantime I have started a solve with multithreading disabled, to 
see if it makes a difference; I might have an answer in the morning.

I will send the MPS just to you to avoid spamming the list.



From:
John Forrest <john.forrest at fastercoin.com>
To:
cbc at list.coin-or.org
Date:
03/08/2013 04:33 PM
Subject:
Re: [Cbc] Cbc segfault after many hours of CPU time



I will take a look at it. Trunk stable ??

John Forrest

On 08/03/13 20:45, acw at ascent.com wrote:
I have a model which I have been trying to solve thus: 

> ./cbc -threads 4 -import trouble.mps -solve -quit 

As you can see, the only even slightly exotic thing I'm doing is enabling 
multithreading, which has worked fine for me with less-challenging models. 


Cbc works on this for several hours and then segfaults.  I tried it three 
times.  On two occasions, it did about 5.5 M nodes before dying (taking 
about half a CPU-day, but only three or four hours of wallclock time).  On 
the third occasion, it managed more than 27 M nodes and 2.5 CPU-days (but 
only overnight by the wall clock). 

On all occasions, the number of nodes on the tree rises rapidly to about 
93 K, then remains approximately constant (within a few hundred) for the 
rest of the ill-fated run. 

Has anyone else had similar experiences? 

I have not yet tried running the model without multithreading, for obvious 
practical reasons: it would probably take twelve hours if I was lucky, and 
might take sixty. 

I'll be glad to share the MPS file (about a quarter of a meg uncompressed) 
with anybody who wants to try this. 

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