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  • 1 reply
  • Latest Post - ‏2013-12-16T15:09:29Z by Philippe_Refalo
Hosssein
Hosssein
26 Posts

Pinned topic Strange high memory usage in cp.startNewSearch() (Version 12.6.0)

‏2013-12-11T20:22:50Z |

Hi,

I have faced with a strange high memory usage in IBM ILOG CPLEX Optimization Studio V12.6.0. Actually I was using Version 12.3, but because of some reasons I have decided to switch to V12.6.

My code in Version 12.3 uses a reasonable level of memory in solving the CP model, but unexpectedly I found that in Version 12.6.0 the same code uses so much memory when it starts reading "cp.startNewSearch()".

The memory usage in my laptop in Version 12.3 is 2.7 GB during solving the CP model (and also when it is reading the the CP search method) but in Version 12.6 when the same code gets to "cp.startNewSearch()" the memory usage suddenly increases to 4.7 GB and after reading this line it decreases to 3.4 GB. This issue strongly decreases the speed of my algorithm and sometimes freezes the computer.

Why does V 12.6.0 behave so strange? I also checked Versions 12.4 and 12.5.1. V12.4 works without any problem, but there is the same issue in V12.5.1.

Updated on 2013-12-12T05:36:04Z at 2013-12-12T05:36:04Z by Hosssein
  • Philippe_Refalo
    Philippe_Refalo
    48 Posts

    Re: Strange high memory usage in cp.startNewSearch() (Version 12.6.0)

    ‏2013-12-16T15:09:29Z  
    Hi Hossein,

     

    Since CPO 12.5, the engine uses presolve to preprocess and simplify the model. For this purpose the engine creates an intermediate model that is presolved and then converted into engine data structures. So, memory always increases due to this conversion but since 12.5 the increase is greater because of this extra model. This model is kept for avoiding further extraction.

     

    The increase in memory is thus a normal behavior and in your case it is about +27% compared to previous version. The problem is the increase to 4.7 Gb  during presolve. Would you mind sending us a .cpo file of your model so that we can investigate ? You can do this using IBM support if you wish.
     
    Regards,
    Philippe
    Updated on 2013-12-16T15:12:11Z at 2013-12-16T15:12:11Z by Philippe_Refalo