Introduced mip_search_concurrency option

Author: jajhall

highs/lp_data/HConst.h

@@ -33,6 +33,7 @@ const std::string kHighsChooseString = "choose";
 const std::string kHighsOnString = "on";
 const HighsInt kHighsMaxStringLength = 512;
 const HighsInt kSimplexConcurrencyLimit = 8;
+const HighsInt kMipSearchConcurrencyLimit = 8;
 const double kRunningAverageMultiplier = 0.05;
 const double kExcessivelyLargeBoundValue = 1e10;
 const double kExcessivelyLargeCostValue = 1e10;

highs/lp_data/HighsOptions.h

@@ -452,6 +452,7 @@ struct HighsOptionsStruct {
   std::string mip_improving_solution_file;
   bool mip_root_presolve_only;
   HighsInt mip_lifting_for_probing;
+  HighsInt mip_search_concurrency;
 
   // Logging callback identifiers
   HighsLogOptions log_options;
@@ -591,10 +592,11 @@ struct HighsOptionsStruct {
 #endif
         mip_improving_solution_save(false),
         mip_improving_solution_report_sparse(false),
-        // clang-format off
         mip_improving_solution_file(""),
         mip_root_presolve_only(false),
-        mip_lifting_for_probing(-1) {};
+        mip_lifting_for_probing(-1),
+        // clang-format off
+        mip_search_concurrency(0) {};
   // clang-format on
 };
 
@@ -1168,6 +1170,11 @@ class HighsOptions : public HighsOptionsStruct {
         &mip_min_logging_interval, 0, 5, kHighsInf);
     records.push_back(record_double);
 
+    record_int = new OptionRecordInt(
+        "mip_search_concurrency", "Concurrency to use in MIP search", advanced,
+        &mip_search_concurrency, 1, 2, kMipSearchConcurrencyLimit);
+    records.push_back(record_int);
+
     record_int = new OptionRecordInt(
         "ipm_iteration_limit", "Iteration limit for IPM solver", advanced,
         &ipm_iteration_limit, 0, kHighsIInf, kHighsIInf);