Merge pull request #23267 from mantidproject/23266_add_GIL_release

Added GIL release to findRuns python calls

Framework/PythonInterface/inc/MantidPythonInterface/kernel/Environment/ReleaseGlobalInterpreterLock.h

+#ifndef MANTID_PYTHONINTERFACE_RELEASEGLOBALINTERPRETERLOCK_H_
+#define MANTID_PYTHONINTERFACE_RELEASEGLOBALINTERPRETERLOCK_H_
+
+#include "MantidPythonInterface/kernel/DllConfig.h"
+#include <boost/python/detail/wrap_python.hpp>
+
+namespace Mantid {
+namespace PythonInterface {
+namespace Environment {
+
+/**
+ * Defines a structure for releaseing the Python GIL
+ * using the RAII pattern. This releases the Python GIL
+ * for the duration of the current scope.
+ */
+class PYTHON_KERNEL_DLL ReleaseGlobalInterpreterLock {
+public:
+  /// Default constructor
+  ReleaseGlobalInterpreterLock();
+  /// Destructor
+  ~ReleaseGlobalInterpreterLock();
+
+private:
+  // Stores the current python trace used to track where in
+  // a python script you are.
+  Py_tracefunc m_tracefunc;
+  PyObject *m_tracearg;
+  /// Saved thread state
+  PyThreadState *m_saved;
+};
+
+} // namespace Environment
+} // namespace PythonInterface
+} // namespace Mantid
+
+#endif /* MANTID_PYTHONINTERFACE_RELEASEGLOBALINTERPRETERLock_H_ */

Framework/PythonInterface/mantid/api/src/Exports/FileFinder.cpp

 #include "MantidAPI/FileFinder.h"
 #include "MantidKernel/WarningSuppressions.h"
+#include "MantidPythonInterface/kernel/Environment/ReleaseGlobalInterpreterLock.h"
 #include <boost/python/class.hpp>
 #include <boost/python/overloads.hpp>
 #include <boost/python/reference_existing_object.hpp>
@@ -20,6 +21,23 @@ GNU_DIAG_ON("conversion")
 GNU_DIAG_ON("unused-local-typedef")
 } // namespace
 
+/**
+ * Runs FileFinder.findRuns after releasing the python GIL.
+ * @param self :: A reference to the calling object
+ * @param hinstr :: A string containing the run number and possibly instrument
+ * to search for
+ */
+std::vector<std::string> runFinderProxy(FileFinderImpl &self,
+                                        std::string hinstr) {
+  //   Before calling the function we need to release the GIL,
+  //   drop the Python threadstate and reset anything installed
+  //   via PyEval_SetTrace while we execute the C++ code -
+  //   ReleaseGlobalInterpreter does this for us
+  Mantid::PythonInterface::Environment::ReleaseGlobalInterpreterLock
+      releaseGlobalInterpreterLock;
+  return self.findRuns(hinstr);
+}
+
 void export_FileFinder() {
   class_<FileFinderImpl, boost::noncopyable>("FileFinderImpl", no_init)
       .def("getFullPath", &FileFinderImpl::getFullPath,
@@ -28,7 +46,7 @@ void export_FileFinder() {
                "Return a full path to the given file if it can be found within "
                "datasearch.directories paths. Directories can be ignored with "
                "ignoreDirs=True. An empty string is returned otherwise."))
-      .def("findRuns", &FileFinderImpl::findRuns, (arg("self"), arg("hintstr")),
+      .def("findRuns", &runFinderProxy, (arg("self"), arg("hintstr")),
            "Find a list of files file given a hint. "
            "The hint can be a comma separated list of run numbers and can also "
            "include ranges of runs, e.g. 123-135 or equivalently 123-35"

Framework/PythonInterface/mantid/kernel/CMakeLists.txt

@@ -89,6 +89,7 @@ set ( SRC_FILES
   src/Registry/TypeRegistry.cpp
   src/Environment/ErrorHandling.cpp
   src/Environment/GlobalInterpreterLock.cpp
+  src/Environment/ReleaseGlobalInterpreterLock.cpp
   src/Environment/WrapperHelpers.cpp
 )
 

Framework/PythonInterface/mantid/kernel/src/Environment/ReleaseGlobalInterpreterLock.cpp

+#include "MantidPythonInterface/kernel/Environment/ReleaseGlobalInterpreterLock.h"
+
+namespace Mantid {
+namespace PythonInterface {
+namespace Environment {
+
+/**
+ * Ensures this thread releases the Python GIL also save trace information
+ * to be restored upon destruction.
+ */
+ReleaseGlobalInterpreterLock::ReleaseGlobalInterpreterLock()
+    : m_tracefunc(nullptr), m_tracearg(nullptr), m_saved(nullptr) {
+  PyThreadState *curThreadState = PyThreadState_GET();
+  m_tracefunc = curThreadState->c_tracefunc;
+  m_tracearg = curThreadState->c_traceobj;
+  Py_XINCREF(m_tracearg);
+  PyEval_SetTrace(nullptr, nullptr);
+  m_saved = PyEval_SaveThread();
+}
+
+/**
+ * Restores the Python GIL to the thread when the object falls out of scope.
+ */
+ReleaseGlobalInterpreterLock::~ReleaseGlobalInterpreterLock() {
+  PyEval_RestoreThread(m_saved);
+  PyEval_SetTrace(m_tracefunc, m_tracearg);
+  Py_XDECREF(m_tracearg);
+}
+
+} // namespace Environment
+} // namespace PythonInterface
+} // namespace Mantid
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