Set maximum threads immediately after parsing paramteres. Remove hotfix.

opm/simulators/flow/FlowMain.hpp

@@ -156,6 +156,9 @@ namespace Opm {
                 }
             }
 
+            // set the maximum limit on OMP threads
+            setMaxThreads();
+
             return status;
         }
 
@@ -278,6 +281,11 @@ namespace Opm {
             mpi_rank_ = comm.rank();
             mpi_size_ = comm.size();
 
+            setMaxThreads();
+        }
+
+        static void setMaxThreads()
+        {
 #if _OPENMP
             // If openMP is available, default to 2 threads per process unless
             // OMP_NUM_THREADS is set or command line --threads-per-process used.

opm/simulators/flow/Main.hpp

@@ -702,47 +702,11 @@ private:
 
     static int getNumThreads()
     {
-
-        int threads;
-
 #ifdef _OPENMP
-        // This function is called before the parallel OpenMP stuff gets initialized.
+        return omp_get_max_threads();
-        // That initialization happens after the deck is read and we want this message.
-        // Hence we duplicate the code of setupParallelism to get the number of threads.
-        static bool first_time = true;
-        constexpr int default_threads = 2;
-        const int requested_threads = Parameters::Get<Parameters::ThreadsPerProcess>();
-        threads = requested_threads > 0 ? requested_threads : default_threads;
-
-        const char* env_var = getenv("OMP_NUM_THREADS");
-        if (env_var) {
-            int omp_num_threads = -1;
-            auto result = std::from_chars(env_var, env_var + std::strlen(env_var), omp_num_threads);
-            const bool can_output = first_time && FlowGenericVanguard::comm().rank() == 0;
-            if (result.ec == std::errc() && omp_num_threads > 0) {
-                // Set threads to omp_num_threads if it was successfully parsed and is positive
-                threads = omp_num_threads;
-                if (can_output && requested_threads > 0) {
-                    std::cout << "Warning: Environment variable OMP_NUM_THREADS takes precedence over the --threads-per-process cmdline argument."
-                              << std::endl;
-                }
-            } else {
-                if (can_output) {
-                    std::cout << ("Warning: Invalid value for OMP_NUM_THREADS environment variable.") << std::endl;
-                }
-            }
-        }
-
-        if (threads != omp_get_max_threads()) {
-            // Set a limit to OMP threads. Defaults can saturate the whole machine.
-            omp_set_num_threads(threads);
-        }
-
-        first_time = false;
 #else
-        threads = 1;
+        return 1;
 #endif
-        return threads;
     }
 
 #if HAVE_DAMARIS