将PuLP与HiGHS CMD求解器结合时，卡在写入解决方案环节

问题场景 #

用Python的PuLP库构建混合整数规划（MIP）模型，采用HiGHS CMD求解器时，Mac系统下几秒即可完成计算，但Windows系统中脚本会卡在prob.solve()步骤。从输出日志来看，HiGHS已经算出最优解并提示"Writing the solution to Arrangement_Pl-pulp.sol"，但脚本始终无法继续执行。

代码片段 #

import pulp as pl

prob = pl.LpProblem("Arrangement Pl", pl.LpMaximize)
cutVariables = pl.LpVariable.dict("cuts", cuts, 0, None, pl.LpInteger)

# 目标函数
prob += pl.lpSum([WidthOrder[i] * cutVariables[i] for i in cuts])
# 约束条件
prob += pl.lpSum([WidthOrder[i] * cutVariables[i] for i in cuts]) <= Deckle
prob += pl.lpSum([cutVariables[i] for i in cuts]) <= maxCuts
for i in cuts:
    prob += cutVariables[i] <= OrderDict[i]

solver = pl.HiGHS_CMD(path=path_to_HiGHS)
result = prob.solve(solver)

求解器输出日志 #

Running HiGHS 1.5.3 [date: 1970-01-01, git hash: 45a127b78]
Copyright (c) 2023 HiGHS under MIT licence terms
MIP  Arrangement_Pl-pulp has 3 rows; 1 cols; 3 nonzeros; 1 integer variables
Presolving model
0 rows, 0 cols, 0 nonzeros
0 rows, 0 cols, 0 nonzeros
Presolve: Optimal

Solving report
  Status            Optimal
  Primal bound      400
  Dual bound        400
  Gap               0% (tolerance: 0.01%)
  Solution status   feasible
                    400 (objective)
                    0 (bound viol.)
                    0 (int. viol.)
                    0 (row viol.)
  Timing            0.01 (total)
                    0.01 (presolve)
                    0.00 (postsolve)
  Nodes             0
  LP iterations     0 (total)
                    0 (strong br.)
                    0 (separation)
                    0 (heuristics)
Writing the solution to Arrangement_Pl-pulp.sol

解决建议 #

• 检查文件读写权限：Windows下PuLP默认会在当前目录生成.lp、.sol等临时文件，若当前目录无写入权限，HiGHS会卡在写文件环节。可尝试用管理员权限运行脚本，或手动指定一个有读写权限的临时目录存放求解器输出文件。
• 禁用临时文件保留：初始化HiGHS_CMD时添加keepFiles=False参数，阻止求解器保留中间文件，避免文件IO阻塞：

  solver = pl.HiGHS_CMD(path=path_to_HiGHS, keepFiles=False)
  

• 切换PuLP内置HiGHS求解器：放弃手动指定HiGHS路径，改用PuLP自带的HiGHS()求解器（无需额外配置路径），避免路径或进程调用的兼容性问题：

  solver = pl.HiGHS()
  result = prob.solve(solver)
  

• 关闭求解器输出：添加msg=False参数关闭HiGHS的日志输出，减少命令行IO交互可能导致的阻塞：

  solver = pl.HiGHS_CMD(path=path_to_HiGHS, msg=False)
  

• 升级依赖版本：当前使用的HiGHS为1.5.3，尝试升级到最新稳定版；同时升级PuLP到最新版本，修复旧版本的Windows兼容bug：

  pip install --upgrade pulp
  

内容的提问来源于stack exchange，提问作者siddharth goel