SCIP多年度优化 clique table cleanup 卡顿问题求助

我正在运行包含连续变量与二进制变量的多年度优化任务：第一年SCIP仅需5秒完成预处理，全程求解耗时不足1分钟；但第二年SCIP卡在clique table cleanup环节，耗时超1小时仍未完成，手动中断后才停止。

问题规模对比 #

第一年问题信息 #

original problem has 249472 variables (4189 bin, 0 int, 0 impl, 245283 cont) and 324123 constraints
presolved problem has 77757 variables (4189 bin, 0 int, 0 impl, 73568 cont) and 63603 constraints

第二年问题信息 #

original problem has 247394 variables (2112 bin, 0 int, 0 impl, 245282 cont) and 299978 constraints

可见第二年问题规模更小（约束与二进制变量更少），理论上求解应更快。我尝试调整clique table相关参数以加速清理，但未取得效果。

第二年运行日志 #

presolving:
(round 1, fast)       111770 del vars, 199370 del conss, 0 add conss, 175207 chg bounds, 0 chg sides, 0 chg coeffs, 0 upgd conss, 2112 impls, 0 clqs
(round 2, fast)       111774 del vars, 199371 del conss, 0 add conss, 228820 chg bounds, 1 chg sides, 0 chg coeffs, 0 upgd conss, 2112 impls, 0 clqs
(round 3, fast)       111774 del vars, 199371 del conss, 0 add conss, 262799 chg bounds, 1 chg sides, 0 chg coeffs, 0 upgd conss, 2112 impls, 0 clqs
(round 4, fast)       111774 del vars, 199371 del conss, 0 add conss, 267181 chg bounds, 1 chg sides, 0 chg coeffs, 0 upgd conss, 2112 impls, 0 clqs
(round 5, fast)       111774 del vars, 199371 del conss, 0 add conss, 269297 chg bounds, 1 chg sides, 0 chg coeffs, 0 upgd conss, 2112 impls, 0 clqs
(round 6, fast)       111774 del vars, 199371 del conss, 0 add conss, 269297 chg bounds, 2114 chg sides, 4224 chg coeffs, 0 upgd conss, 2112 impls, 0 clqs
   (3.0s) running MILP presolver
   (4.0s) MILP presolver (8 rounds): 21903 aggregations, 2 fixings, 6504 bound changes
(round 7, medium)     133680 del vars, 199372 del conss, 0 add conss, 275801 chg bounds, 2114 chg sides, 4224 chg coeffs, 0 upgd conss, 2112 impls, 0 clqs
(round 8, fast)       138055 del vars, 230038 del conss, 0 add conss, 275801 chg bounds, 4228 chg sides, 8448 chg coeffs, 0 upgd conss, 2112 impls, 0 clqs
(round 9, exhaustive) 138057 del vars, 234415 del conss, 0 add conss, 275811 chg bounds, 4228 chg sides, 8448 chg coeffs, 0 upgd conss, 2112 impls, 0 clqs
(round 10, exhaustive) 138057 del vars, 234415 del conss, 0 add conss, 275823 chg bounds, 4230 chg sides, 8448 chg coeffs, 2112 upgd conss, 2112 impls, 0 clqs
   (5.0s) probing: 52/2112 (2.5%) - 2 fixings, 0 aggregations, 0 implications, 0 bound changes
   (5.0s) probing aborted: 50/50 successive totally useless probings
   (5.0s) symmetry computation started: requiring (bin +, int -, cont +), (fixed: bin -, int +, cont -)
   (7.0s) symmetry computation finished: 585 generators found (max: 585, log10 of symmetry group size: inf) (symcode time: 2.00)
   (7.0s) no symmetry on binary variables present.
pressed CTRL-C 1 times (5 times for forcing termination)
(round 11, exhaustive) 138061 del vars, 234417 del conss, 171405 add conss, 275835 chg bounds, 4232 chg sides, 8448 chg coeffs, 2112 upgd conss, 2112 impls, 0 clqs
presolving (11 rounds: 11 fast, 4 medium, 3 exhaustive):
 138061 deleted vars, 234417 deleted constraints, 171405 added constraints, 275835 tightened bounds, 0 added holes, 4232 changed sides, 8448 changed coefficients
 2112 implications, 0 cliques
presolving was interrupted.
Presolving Time: 560.00

SCIP Status        : solving was interrupted [user interrupt]
Solving Time (sec) : 562.00
Solving Nodes      : 0
clique table cleanup detected 0 bound changes

可行解决方案建议 #

• 禁用clique table相关预处理：直接关闭clique处理模块，避免卡在清理环节，设置参数 set presolving/clique/enable false，或针对性关闭clique table清理：set presolving/clique/cleanup/enable false。
• 限制预处理强度与时间：减少预处理轮次，设置 set presolving/maxrounds 5；或给预处理设置时间上限：set presolving/maxtime 30（单位秒），超时后直接进入求解阶段。
• 调整对称性检测参数：日志中显示对称性计算找到大量生成器，虽提示无二进制变量对称性，但可能存在额外开销，可关闭对称性检测：set symmetry/enable false，或限制计算时间：set symmetry/maxcomputationtime 10。
• 分析问题结构差异：第二年连续变量规模与第一年几乎一致，可能约束结构存在特殊耦合，可导出预处理后模型：write problem presolved.lp，检查是否存在异常约束或变量关联。
• 更新SCIP版本：若使用旧版本，可能存在clique table清理的性能bug，升级到最新稳定版（如8.x系列）可能解决问题。
• 调整内存优化策略：尝试设置 set memory/emphasis speed，让SCIP优先考虑速度而非内存优化，避免内存分配相关卡顿。

内容的提问来源于stack exchange，提问作者gcalado