[Scip] 70% of solving time is spent in checkLazyColArray
Sebastian Ruther
Sebastian.Ruther at uon.edu.au
Fri Aug 10 08:14:06 MEST 2012
Hello,
I noticed that a large amount of time is spent in checkLazyColArray. Of
a time limit of 4h about 10k seconds (i.e. 70%) are spend in this
function. Btw, this time is not accounted for in the output generated by
SCIPprintStatistics.
The function has 2 double loops over nlazycols and ncols. When this
function is called the first time, both are close to 40k. At that point
the function takes 12 seconds to run. The function is called frequently
when switching to a different node but not every time.
I assume that usually a larger number of columns can be handled by SCIP
which would suggest that this function should not be called often as it
is very expensive. So the question is: what can I do to avoid calling it?
Why does it shrink columns? Not sure if it has anything to do with it
but I don't have colagelimit or cleanupcols(root) activated.
The call stack is
checkLazyColArray
SCIPlpShrinkCols
SCIPtreeLoadLP
SCIPconstructCurrentLP
solveNodeInitialLP
solveNodeLP
propAndSolve
solveNode
SCIPsolveCIP
SCIPsolve
runSCIP
FYI I'm still running SCIP 2.1.1
Thank you for your help,
Sebastian
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