Task Scheduler with Resource Pools and Capacity

[Ricardo Mendes]

Hello,

 

I'm new to Or-Tools but I'm consider using it as a constraint solver framework to develop a Task Scheduler Engine.

I need to orchestrate a pool of multi-resources and be able assign one or more of them to each task, allow some variable degree of overlap for each task, include resource calendar…

 

Is Or-Tools a feasible approach? There are any C# scheduling examples besides JobShop?

 

Best Regards

[Laurent Perron]

Hi, 

The gate scheduling is also a scheduling problem.

Otherwise, you can look at the python examples, in particular examples/python/rcpsp_sat.py which cover a lot of scheduling constraints.

Modeling wise, examples/cpp/jobshop_sat.cc also shows complex features, in particular transition times between tasks.

Finally, https://github.com/google/or-tools/blob/master/ortools/sat/doc/index.md has a section on scheduling.

It is mostly not written, but I can add relevant code snippets if needed.

Thanks

Laurent Perron | Operations Research | lpe...@google.com | (33) 1 42 68 53 00

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[Jing Liu]

Thank you Laurent.

It is really helpful. But I was wondering if there is a way to get the name assigned to a IntervalVar. 

For instance, I declared a IntervalVar: IntervalVar interval =  model.NewIntervalVar(start_var, duration, end_var, "task 1"); How can I get the name (i.e., task 1) of interval later?

I am using C#.

Thank you.

[Laurent Perron]

Hi, 

I have added a name method in C#/Python for IntVar and IntervalVar.

This is live on github.

I should be available in the 6.8 release (soon).

Thanks

Laurent Perron | Operations Research | lpe...@google.com | (33) 1 42 68 53 00

[Jing Liu]

Awesome. It would be great if you can add one more function in getting the duration for IntervalVar.

Thank you,

[Laurent Perron]

This one may not be fixed.

So it is better if you do the book keeping on your side.

--Laurent

Laurent Perron | Operations Research | lpe...@google.com | (33) 1 42 68 53 00

[Jing Liu]

Thank you for your quick reply. OK, I will record the duration when declaring a new IntervalVar.

Thank you,

Jing

[Jing Liu]

Could you please post some code snippets on modeling precedence relationships between intervals? I am trying to model a rcpsp problem using C#

Thank you,

On Wednesday, June 27, 2018 at 10:34:56 AM UTC-6, Laurent Perron wrote:

[Laurent Perron]

See jobshop_ft06_sat.cs, the section on precedence.

Get back the start and end variables of the intervals, and add

model.Add(start_of_second_interval >= end_of_first_interval);

[Jing Liu]

What if I need to add some lag time between two tasks? Now I am using the following code and not sure if it is correct. Because I found that I cannot add one IntVar and one int.

model.Add(start_of_second_interval >= end_of_first_interval + model.NewConstant(lagTime));

Thanks,

Jing

[Laurent Perron]

In C# ad python, you can easily add integer to variables.

Laurent Perron | Operations Research | lpe...@google.com | (33) 1 42 68 53 00

[Ricardo Mendes]

Hi, 

Where can I find a sample in C# addressing resource pools. I'm not familiar with python, so rcpsp_sat.py is not usefull to me.

Regards

[Ricardo Mendes]

Hi,

I created this thread, but I was allocated to other projects, and I didn't had further improvments in this area.

Do you succeded modeling a rcpsp problem using C#? I hope back to schedulling engine soon.

Regards

[Laurent Perron]

We have added more examples, and an doc section on it:

https://github.com/google/or-tools/blob/stable/ortools/sat/doc/scheduling.md

Laurent Perron | Operations Research | lpe...@google.com | (33) 1 42 68 53 00