docplex.cp.model 集群内存不足运行

Question

我正在尝试运行以下 docplex.cp.model 大型数据集。这是一些示例数据：

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())

我已尝试运行使用以下设置在集群上执行此操作：

#SBATCH --nodes=2
#SBATCH --ntasks-per-node=4
#SBATCH --mem-per-cpu=4571

这在 out-of-memory 处停止，如输出所示：

! --------------------------------------------------- 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') #agent='local',execfile='/Users/Mine/Python/tf2_4_env/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.

我观察到的是优化是运行ning 并行，正如它所说 Using parallel search with 28 workers 并且每个节点有 28 个核心。但是看起来它只使用了 1 个节点。

你能帮我解决内存不足的问题吗？

Answer 1

默认情况下，CPO 求解器启动的工作线程数与可见内核数一样多，包括超线程。不幸的是，内存消耗几乎与工作人员数量成正比，这解释了您的“内存不足”。

您应该通过在您的解决请求中添加例如 Workers=4 来限制此数量，在您的情况下会变成：

sol=m.solve(agent='local',execfile='/Users/Mine/Python/tf2_4_env/bin/cpoptimizer', Workers=4)

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