Close Active Sessions

Answered

Sam Mugel

January 23, 2025 12:36 Edited

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Hello,

I am using Gurobi with gurobipy. I wanted to ask if there is a way of closing an open session right after my jobs finish.

My observations indicate that once a job starts, gurobi creates a session, a running container and a 5 min token. The three components are disposed after 5 minutes even if my job takes only 1 second to compute.

Also, the dashboard shows the session open for at least 10 minutes, although after that I can see in the table that it only lasted 5 minutes. I am wondering if this could be a bug of some sort.

Thanks in advance for your time

Related to

• WLS (Web License Service)

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  David Torres Sanchez

  • Gurobi Staff

  January 23, 2025 12:12

  Hi Sam,

  This sounds like a WLS license. In that case, your token will be held for a minimum of 5 minutes (this can be changed with a parameter) if the environments and models are disposed of correctly: How do I manage Gurobi environments in gurobipy?

  Cheers, 
  David

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  Sam Mugel

  January 23, 2025 12:34

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  Thanks David!
  Yes, it is a WLS license :)
  
  It took me some time to dispose my resources correctly but I think I'm doing it correctly now. Could you share more details about this parameter that you mention so I can manage my token lifetime? I'm sorry I could not find references for this in the docs.

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  David Torres Sanchez

  • Gurobi Staff

  January 23, 2025 12:54 Edited

  Hi Sam,

  Cool! The parameter is WLSTokenDuration though this needs to be set at the environment level. 
  Similarly with other connection parameters (e.g. see mip1_remote.py).

  Cheers, 
  David

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  Sam Mugel

  January 23, 2025 15:28 Edited

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  Thank you for your quick response. I followed your instructions but unfortunately, my token management is ignored if the time is set to 1. However, It works for 6 seconds. Is 5 minutes the minimum time that a session can be running? 

  with gp.Env(empty=True) as env:
  
      env.setParam("WLSTokenDuration", 1)
      env.start()
  
      with gp.Model(env=env) as gurobi_model:
          # optimize

   

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  David Torres Sanchez

  • Gurobi Staff

  January 23, 2025 16:13

  Good catch. We allow smaller values than 5 (minutes), but these get rounded up to 5. From the same place in the docs

  The WLS server will cap the chosen value automatically to be at least 5 minutes and no more than 60 minutes. This behavior may change in the future as well.

  You can set the parameter like this:

  with gp.Env(params={"WLSTokenDuration": 1}) as env:
      with gp.Model(env=env) as gurobi_model:
          # optimize

  If you want, you can reuse the environment for multiple Gurobi models if that helps.

  Cheers, 
  David

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