[Coin-discuss] Massive slowdown and increased memory usage with OsiClp

[Lasse Kliemann]

Greetings,

I have some code here that used to work fine the last time 
around July 2005. It uses an object OsiSolverInterface to 
solve a rather large LP, which is built with CoinModel. I did 
not use this code for some time until December 2005. So in 
December, I got the current version of COIN from the CVS and 
compiled my code against it. Compilation went fine, so did 
runs on smaller instances, although they seemed slower to me. 
Then, the larger instances showed a terrible performance. 
Computation took several times longer than before, and the 
memory usage increased dramatically. Instances that in July I 
could solve in, say, 20 seconds now took minutes and nearly 
one GB of RAM. The problem remains with the version from CVS 
that I fetched today.

Fortunately, I still have a copy of the old version of COIN 
around. Compiling my code against this old version leads to 
the good performance, that I remember.

What has happened to COIN that it became pratically unusable 
for my project? It worked absolutely fine before.

I noticed that during the run of the solver, there is more 
output to the console than before. Maybe I have enabled some 
sort of debugging mode, that makes it all run so slow and so 
memory-hungry?


This was a rough overview. I am not sure what details could be 
of interest. I still hope that it is an easy issue that can be 
solved by switching off some debugging mode or such. If not, 
I will be happy to provide any details necessary.


Thanks a lot,
Lasse Kliemann