Originally posted by: cynnudt

Hi,

I am using c++ to code with CPLEX.  Part of my code is to invoke CPLEX to help me solve an Integer programming problem, where I impose a time limit of 10 seconds. After each invoke, I need to check how much time left to run the follwing procedure. This is done by using clock() function of time.h in C++.

I run my code both in  my personal computer and in cluster. It works well in my personal computer. But when I run in cluster, after each time of 10s' invoke, the clock() returns a value significantly larger than 10s, which is absolutely wrong. I use CPLEX 12.2 in my personal computer, and CPLEX 12.4 in cluster.

I doubt whether CPLEX  has some influence on cluster's time synchronization. I don't know. Anyone who can help me?

Thank you!

Chen

Does the problem persist if you explicit set CPX_PARAM_THREADS to 1?

The clock() function measures elapsed CPU time (and not wallclock time). On some systems this may include time for child processes and/or threads. That may explain why the time measured by clock() does not match wallclock time.

A better way to measure time would to use gettimeofday() or CPXgettime() (provided you did not set the CPLEX time to CPU time).