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LPBACKGROUNDTHREADS

Description
Specifies the maximum number of threads to use for background work (typically heuristics) in parallel to the root LP relaxation of a MIP. This control can help finding feasible MIP solutions fast for models with difficult root LP relaxation. The algorithm employed is similar to the one used during pre-root parallel heuristics.
Type
Integer
Topic areas
LP, Parallel
Values
-1 
Automatic selection of LP background threads depending on the choice of HEUREMPHASIS.
0 
Disable LP background threads
>0 
Enabled. Specifies the number of threads reserved for LP background work.
Default value
-1
Notes

This control can be used to enable, disable, and tune the share of work dedicated to heuristics during the LP root relaxation. A specific choice of LP background threads has a direct consequence on the number of threads that the Optimizer uses for the LP relaxation. Users should avoid to manually specify more threads than physical cores are available on the host computer.
The default behavior of this control is subject to the choice of HEUREMPHASIS. If HEUREMPHASIS=1 or higher, some of the available threads (typically 25%) are used for LP background work.
The heuristic algorithm employed is similar to the algorithm used inside pre-root parallel heuristics.
Every LP background thread increases the memory consumption of the search during the initial root relaxation. Use this control to limit or disable LP background work, if you encounter memory errors during the root relaxation.
Affects routines
XPRSmipoptimize ( MIPOPTIMIZE), XPRSoptimize ( OPTIMIZE).
See also
THREADS, CONCURRENTTHREADS, PREROOTTHREADS, BACKGROUNDMAXTHREADS.
Category
Control

Parent Topic Control Parameters

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