Refactor OpenMP thread handling and remove redundant omp_set_num_threads calls

Updated `#pragma omp parallel` statements to explicitly define `num_threads` using `ppc::util::GetNumThreads()`. Removed redundant `omp_set_num_threads` calls in runners, streamlining thread configuration across the codebase.

Author: allnes

tasks/common/runners/functional.cpp

@@ -76,8 +76,6 @@ int main(int argc, char** argv) {
 
     // Limit the number of threads in TBB
     tbb::global_control control(tbb::global_control::max_allowed_parallelism, ppc::util::GetNumThreads());
-    // Limit the number of threads in OMP
-    omp_set_num_threads(ppc::util::GetNumThreads());
 
     ::testing::InitGoogleTest(&argc, argv);
 
@@ -97,8 +95,6 @@ int main(int argc, char** argv) {
 
   // Limit the number of threads in TBB
   tbb::global_control control(tbb::global_control::max_allowed_parallelism, ppc::util::GetNumThreads());
-  // Limit the number of threads in OMP
-  omp_set_num_threads(ppc::util::GetNumThreads());
 
   ::testing::InitGoogleTest(&argc, argv);
   return RUN_ALL_TESTS();

tasks/common/runners/performance.cpp

@@ -75,8 +75,6 @@ int main(int argc, char** argv) {
 
   // Limit the number of threads in TBB
   tbb::global_control control(tbb::global_control::max_allowed_parallelism, ppc::util::GetNumThreads());
-  // Limit the number of threads in OMP
-  omp_set_num_threads(ppc::util::GetNumThreads());
 
   ::testing::InitGoogleTest(&argc, argv);
 

tasks/common/tests/util.cpp

@@ -13,7 +13,7 @@ TEST(ppc_func_tests_common, threads_control_check_openmp) {
   int ppc_num_threads = ppc::util::GetNumThreads();
 
   int omp_num_threads = -1;
-#pragma omp parallel default(none) shared(omp_num_threads)
+#pragma omp parallel default(none) shared(omp_num_threads) num_threads(ppc::util::GetNumThreads())
   omp_num_threads = omp_get_num_threads();
 
   // Check Result

tasks/example/all/src/ops_all.cpp

@@ -46,7 +46,7 @@ bool NesterovATestTaskALL::RunImpl() {
     MPI_Comm_rank(MPI_COMM_WORLD, &rank);
     if (rank == 0) {
       std::atomic<int> counter(0);
-#pragma omp parallel default(none) shared(counter)
+#pragma omp parallel default(none) shared(counter) num_threads(ppc::util::GetNumThreads())
       counter++;
 
       GetOutput() /= counter;

tasks/example/omp/src/ops_omp.cpp

@@ -35,7 +35,7 @@ bool NesterovATestTaskOMP::RunImpl() {
   GetOutput() *= num_threads;
 
   std::atomic<int> counter(0);
-#pragma omp parallel default(none) shared(counter)
+#pragma omp parallel default(none) shared(counter) num_threads(ppc::util::GetNumThreads())
   counter++;
 
   GetOutput() /= counter;