Always hook omp functions in Mac (#2128)

* always hook omp functions in Mac

* fix recent test failures with the latest qiskit

---------

Co-authored-by: Jun Doi <doichan@jp.ibm.com>

qiskit_aer/backends/backend_utils.py

@@ -25,6 +25,9 @@
 
 from .compatibility import Statevector, DensityMatrix, StabilizerState, Operator, SuperOp
 
+# pylint: disable=import-error, no-name-in-module, abstract-method
+from .controller_wrappers import aer_initialize_libraries
+
 # Available system memory
 SYSTEM_MEMORY_GB = psutil.virtual_memory().total / (1024**3)
 
@@ -35,6 +38,7 @@
 # Location where we put external libraries that will be
 # loaded at runtime by the simulator extension
 LIBRARY_DIR = os.path.dirname(__file__)
+aer_initialize_libraries(LIBRARY_DIR)
 
 LEGACY_METHOD_MAP = {
     "statevector_cpu": ("statevector", "CPU"),

qiskit_aer/backends/wrappers/aer_controller_binding.hpp

@@ -86,6 +86,8 @@ void read_value(const py::tuple &t, size_t index, T &v) {
 
 template <typename MODULE>
 void bind_aer_controller(MODULE m) {
+  m.def("aer_initialize_libraries", &initialize_libraries);
+
   py::class_<ControllerExecutor<Controller>> aer_ctrl(m,
                                                       "aer_controller_execute");
   aer_ctrl.def(py::init<>());

releasenotes/notes/init_omp_first-c9d19dbfa1a0fc2b.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    In Mac, to use OpenMP, setup of hooks to omp functions is necessary. However, this setup
+    works only for backend services and not for quantum_info classes of ``AerStatevector`` and
+    ``AerDensityMatrix``. This fix calls the setup in quantum_info also. 

src/controllers/controller_execute.hpp

@@ -29,18 +29,15 @@
 
 namespace AER {
 
+void initialize_libraries(const std::string &lib_dir) {
+  // Fix for MacOS and OpenMP library double initialization crash.
+  // Issue: https://github.com/Qiskit/qiskit-aer/issues/1
+  Hacks::maybe_load_openmp(lib_dir);
+}
+
 template <class controller_t, typename inputdata_t>
 Result controller_execute(const inputdata_t &qobj) {
   controller_t controller;
-
-  // Fix for MacOS and OpenMP library double initialization crash.
-  // Issue: https://github.com/Qiskit/qiskit-aer/issues/1
-  if (Parser<inputdata_t>::check_key("config", qobj)) {
-    std::string path;
-    const auto &config = Parser<inputdata_t>::get_value("config", qobj);
-    Parser<inputdata_t>::get_value(path, "library_dir", config);
-    Hacks::maybe_load_openmp(path);
-  }
   return controller.execute(qobj);
 }
 
@@ -229,9 +226,6 @@ Result controller_execute(std::vector<std::shared_ptr<Circuit>> &input_circs,
   auto time_taken =
       std::chrono::duration<double>(myclock_t::now() - timer_start).count();
 
-  // Fix for MacOS and OpenMP library double initialization crash.
-  // Issue: https://github.com/Qiskit/qiskit-aer/issues/1
-  Hacks::maybe_load_openmp(config.library_dir);
   controller.set_config(config);
   auto ret = controller.execute(circs, noise_model, config);