Optimize large number of nodes

[Prateek Khandelwal]

I'm using ortools (version: 9.3) in python to generate routes with constraints, I'm running the solver with ~1200 orders with capacity, service time, weight and some other constraints on vehicles and not getting the same result when splitting the data into clusters (5) with almost equal orders. I found this thread (https://groups.google.com/g/or-tools-discuss/c/ViEPGrYBils), but couldn't find an example of how to enable caching or pass time matrix to the solver. How can I optimize this and get the same result as small clusters.

```

# Setting first solution heuristic.

search_parameters = pywrapcp.DefaultRoutingSearchParameters()

if (

route_group_config["first_solution_strategy"]

== constants.PARALLEL_CHEAPEST_INSERTION

):

search_parameters.first_solution_strategy = (

routing_enums_pb2.FirstSolutionStrategy.PARALLEL_CHEAPEST_INSERTION

)

else: # default PATH_CHEAPEST_ARC

search_parameters.first_solution_strategy = (

routing_enums_pb2.FirstSolutionStrategy.PATH_CHEAPEST_ARC

)

search_parameters.local_search_metaheuristic = (

routing_enums_pb2.LocalSearchMetaheuristic.GUIDED_LOCAL_SEARCH

)

search_parameters.time_limit.FromSeconds(int(solution_time))

```

Let me know if more details are required.

[watchdogs132]

This seems relevant! 

https://groups.google.com/g/or-tools-discuss/c/yWdZm6nJLxI/m/qaiJMF5EAAAJ

[Prateek Khandelwal]

@watchdogs132 Did it work for you? Enabling cache and setting limit using ABSL doesn't work in python? Can we just use RoutingModelParameters (https://github.com/google/or-tools/blob/82750ac12f1ee5354e1c7869894d9af3508778f2/ortools/constraint_solver/routing_flags.cc#L335)?

[Prateek Khandelwal]

It did help in iterating more solutions but still didn't get the same number of solutions when splitting the problems into small chunks.