During solving my problem using generic lazy cuts (in Benders decomposition fashion), the solver gets stuck logging out "Performing restart 2" for several hours (while the time limit is 30 min), till I quit it manually .

Based on my searches this situation roots in "Dynamic search" parameter (https://www.ibm.com/docs/en/icos/20.1.0?topic=parameters-mip-dynamic-search-switch), so I turned it off, but the problem still exists.

When I throttle CPLEX down to a single thread, it works fairly better,  i.e., passes some instances that used to stuck, but, still remains on "Performing restart" phases for others. 

I would be grateful, if someone can help.

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Amir Hosseini
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Do you have access to IBM support? Indeed, it seems difficult to be able to help you without your code.

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Thierry Sola
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Dear Thierry Sola,

Many thanks for your reply. 

I haven't contacted IBM supports yet, but I think, the problem that I face roots in a general case, independent of my codes.

But, I can explain the structure of my codes hoping it helps.  I am trying to solve an MILP using single-tree logic-based benders decomposition based on "lazy constraints". In this fashion, during the branch-and-bound tree, anytime an incumbent solution is find, a set of cuts (lazy constraints) are added to the problem and then the solver proceed to next node. Does it help? 

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Amir Hosseini
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Original Message:
Sent: Fri March 22, 2024 10:35 AM
From: Thierry Sola
Subject: CPLEX gets stuck in "Performing restart"

Do you have access to IBM support? Indeed, it seems difficult to be able to help you without your code.

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Thierry Sola
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Hi

How to contact our support team ?

https://www.ibm.com/support/pages/contact-decision-optimization-support-team

regards

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[Alex] [Fleischer]
[Data and AI Technical Sales]
[IBM]
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Original Message:
Sent: Fri March 22, 2024 11:04 AM
From: Amir Hosseini
Subject: CPLEX gets stuck in "Performing restart"

Dear Thierry Sola,

Many thanks for your reply. 

I haven't contacted IBM supports yet, but I think, the problem that I face roots in a general case, independent of my codes.

But, I can explain the structure of my codes hoping it helps.  I am trying to solve an MILP using single-tree logic-based benders decomposition based on "lazy constraints". In this fashion, during the branch-and-bound tree, anytime an incumbent solution is find, a set of cuts (lazy constraints) are added to the problem and then the solver proceed to next node. Does it help? 

------------------------------
Amir Hosseini
------------------------------


Original Message:
Sent: Fri March 22, 2024 10:35 AM
From: Thierry Sola
Subject: CPLEX gets stuck in "Performing restart"

Do you have access to IBM support? Indeed, it seems difficult to be able to help you without your code.

------------------------------
Thierry Sola