Originally posted by: Stidsen

Hi

I am running a customized Branch & Cut algorithm, where I use Cplex
cutcallback, incumbentcallback and branchcallback. I have a problem
with controlling the memory consumption ... It seems that the standard
parameters (CPX_PARAM_TRELIM, CPX_PARAM_WORKMEM and CPX_PARAM_NODEFILEIND)
have no effect. That is ok, if I could just somehow FROM INSIDE MY CALLBACKS
get an estimate of the current memory usage ... then I could terminate
the code my self ... Does anybody know how to get such an estimate ...
(it does not have to be very precise). And yes, I know I can get counts
on the current no of nodes, but depending on the problem instance, same number
of nodes can have very different memory usage ...

Any help will be appreciated !

Best Regards Thomas Stidsen
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Originally posted by: SystemAdmin

This is a very complicated issue. Actually, if someone says "how much memory is consumed" it is not really clear what this means.

For example, one way of measuring memory is the total amount of virtual memory that is allocated by the process. But this does not necessarily mean that the memory is actually paged into physical memory. You can easily allocate several GB of memory without doing any harm to your machine, as long as you are not actually using all the memory at the same time.

Accessing the memory statistics is not easily portable across multiple platforms. But if you just want to have a solution for your platform, then you may be able to find the appropriate OS calls. On Linux, for example, you could read out the proc file system to get some statistics.

Tobias
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Originally posted by: SystemAdmin

Wait, are you saying that these parameters are ignored?
Or is it just that they do not provide enough granularity?

As Tobias said, assessing the actual memory consumption of a process is kind of difficult. On Linux/Unix operating systems you may read the /proc file system (as suggested by Tobias) or use function getrusage() directly. In Windows GetProcessMemoryInfo() may help. In any case, make sure that you do not compare virtual memory ...
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Originally posted by: Stidsen

Hi Daniel

Yes I am saying that the parameters are ignored ... at least I cannot make them work ... I have tried to set them in a number of different ways but the program
seems to ignore them and my memory usage (on the bigger examples) simply grows and grows until the OS (Linux) shuts the process down.

My current best guess is that these parameters stop having an effect when you start to use callbacks .... (I may be wrong).

Comments ?

Best Regards Thomas
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Originally posted by: SystemAdmin

No, parameters should work even if callbacks are present.
I just wrote a short test program to confirm that.
What values did you try for the parameters?
I take it you set the parameters before you invoke CPXmipopt() and not from the callbacks (which would be wrong).
Are you attaching user data to nodes via the branch-callback (CPLEX has no means to keep track of the size of that data).
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