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I solved an MIP problem, with making the solving process sleep for 1 second every branch using BranchCallback (single thread). I noticed from the log that the system time measured in seconds changed every run, while the deterministic time measured in ticks didn't. However, the problem was that the latter didn't even change whether the 1-second sleep was applied or not. On the contrary, The system time did record the sleep time.

I also tried to get the deterministic time using the callback api, but it only counted 0.0 ticks for the 1-second sleep. It's not a problem about the sleep mode, because a simple piece of code counting for a large number also showed 0.0 ticks. I thought it might not record the code running time.

What exactly does the determministic time measure in CPLEX? Is there any method to measure the real running time (especially the real callback running time) as the system time did, but in a deterministic way?

Icarus
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The deterministic time is an approximation for the work that CPLEX does (you can think of it as number of instructions executed inside CPLEX). Doing nothing does not execute any instructions so does not count towards deterministic time.

Moreover, deterministic time is only measured inside CPLEX. It does not account for time spent in user code like callbacks.

If you want to measure the time spent in your callback then you have to do that yourself (there is no point for CPLEX to track this): just take a time stamp at the beginning of your callback, one at the end of your callback and then compute the difference. The CPLEX callbacks have functions to take time stamps, see the reference documentation.

In case you want to have a determinstic time for code you wrote then you have to roll your own and first of all define what deterministic time means for your code.

Daniel Junglas
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