I am trying to run the following `docplex.cp.model`

with a large dataset. This is with some sample data:

```
import numpy as np
from docplex.cp.model import CpoModel
N = 180000
S = 10
k = 2
u_i = np.random.rand(N)[:,np.newaxis]
u_ij = np.random.rand(N*S).reshape(N, S)
beta = np.random.rand(N)[:,np.newaxis]
m = CpoModel(name = 'model')
R = range(1, S)
idx = [(j) for j in R]
I = m.binary_var_dict(idx)
m.add_constraint(m.sum(I[j] for j in R)<= k)
total_rev = m.sum(beta[i,0] / ( 1 + u_i[i,0]/sum(I[j] * u_ij[i-1,j] for j in R) ) for i in range(N) )
m.maximize(total_rev)
sol=m.solve(agent='local',execfile='/Users/Mine/Python/tf2_4_env/bin/cpoptimizer')
print(sol.get_solver_log())
```

I have tried to run this on a cluster with following settings:

```
```

This stops with `out-of-memory`

as shown in the output :

```
! --------------------------------------------------- CP Optimizer 20.1.0.0 --
! Maximization problem - 9 variables, 1 constraint
! Presolve : 360001 extractables eliminated
! Initial process time : 28.95s (28.77s extraction + 0.19s propagation)
! . Log search space : 9.0 (before), 9.0 (after)
! . Memory usage : 623.2 MB (before), 623.2 MB (after)
! Using parallel search with 28 workers.
! ----------------------------------------------------------------------------
! Best Branches Non-fixed W Branch decision
0 9 -
+ New bound is 80920.82
Traceback (most recent call last):
File "sample.py", line 22, in <module>
sol=m.solve(agent='local',execfile='/home/wbs/bstqhc/.local/bin/cpoptimizer')
File "/home/wbs/bstqhc/.local/lib/python3.7/site-packages/docplex/cp/model.py", line 1222, in solve
msol = solver.solve()
File "/home/wbs/bstqhc/.local/lib/python3.7/site-packages/docplex/cp/solver/solver.py", line 775, in solve
raise e
File "/home/wbs/bstqhc/.local/lib/python3.7/site-packages/docplex/cp/solver/solver.py", line 768, in solve
msol = self.agent.solve()
File "/home/wbs/bstqhc/.local/lib/python3.7/site-packages/docplex/cp/solver/solver_local.py", line 209, in solve
jsol = self._wait_json_result(EVT_SOLVE_RESULT)
File "/home/wbs/bstqhc/.local/lib/python3.7/site-packages/docplex/cp/solver/solver_local.py", line 545, in _wait_json_result
data = self._wait_event(evt)
File "/home/wbs/bstqhc/.local/lib/python3.7/site-packages/docplex/cp/solver/solver_local.py", line 448, in _wait_event
evt, data = self._read_message()
File "/home/wbs/bstqhc/.local/lib/python3.7/site-packages/docplex/cp/solver/solver_local.py", line 604, in _read_message
frame = self._read_frame(6)
File "/home/wbs/bstqhc/.local/lib/python3.7/site-packages/docplex/cp/solver/solver_local.py", line 664, in _read_frame
raise CpoSolverException("Nothing to read from local solver process. Process seems to have been stopped (rc={}).".format(rc))
docplex.cp.solver.solver.CpoSolverException: Nothing to read from local solver process. Process seems to have been stopped (rc=-9).
slurmstepd: error: Detected 2 oom-kill event(s) in step 379869.batch cgroup. Some of your processes may have been killed by the cgroup out-of-memory handler.
```

What I observed is the optimisation is running parallel as it says

`Using parallel search with 28 workers`

and there are 28 cores per node. However looks like its only using 1 node.

Can you please help me to overcome the out-of-memory issue?

------------------------------

SHanaka Perera

------------------------------