Add support for Python subinterpreters

Note, at this time, NumPy does not support subinterpreters, and so we do
not either.

Author: QuLogic

src/_backend_agg_wrapper.cpp

@@ -1,6 +1,10 @@
 #include <pybind11/pybind11.h>
 #include <pybind11/numpy.h>
 #include <pybind11/stl.h>
+#ifdef PYBIND11_HAS_SUBINTERPRETER_SUPPORT
+#include <pybind11/subinterpreter.h>
+#endif
+
 #include "mplutils.h"
 #include "py_converters.h"
 #include "_backend_agg.h"
@@ -214,7 +218,11 @@ PyRendererAgg_draw_gouraud_triangles(RendererAgg *self,
     self->draw_gouraud_triangles(gc, points, colors, trans);
 }
 
-PYBIND11_MODULE(_backend_agg, m, py::mod_gil_not_used())
+PYBIND11_MODULE(_backend_agg, m, py::mod_gil_not_used()
+#ifdef PYBIND11_HAS_SUBINTERPRETER_SUPPORT
+                ,py::multiple_interpreters::per_interpreter_gil()
+#endif
+)
 {
     py::classh<RendererAgg>(m, "RendererAgg", py::buffer_protocol())
         .def(py::init<unsigned int, unsigned int, double>(),

src/_image_wrapper.cpp

@@ -1,6 +1,9 @@
 #include <pybind11/pybind11.h>
 #include <pybind11/native_enum.h>
 #include <pybind11/numpy.h>
+#ifdef PYBIND11_HAS_SUBINTERPRETER_SUPPORT
+#include <pybind11/subinterpreter.h>
+#endif
 
 #include <algorithm>
 
@@ -279,7 +282,11 @@ calculate_rms_and_diff(py::array_t<unsigned char> expected_image,
 }
 
 
-PYBIND11_MODULE(_image, m, py::mod_gil_not_used())
+PYBIND11_MODULE(_image, m, py::mod_gil_not_used()
+#ifdef PYBIND11_HAS_SUBINTERPRETER_SUPPORT
+                ,py::multiple_interpreters::per_interpreter_gil()
+#endif
+)
 {
     py::native_enum<interpolation_e>(m, "_InterpolationType", "enum.Enum")
         .value("NEAREST", NEAREST)

src/_path_wrapper.cpp

@@ -1,5 +1,8 @@
 #include <pybind11/pybind11.h>
 #include <pybind11/stl.h>
+#ifdef PYBIND11_HAS_SUBINTERPRETER_SUPPORT
+#include <pybind11/subinterpreter.h>
+#endif
 
 #include <array>
 #include <limits>
@@ -310,7 +313,11 @@ Py_is_sorted_and_has_non_nan(py::object obj)
     return result;
 }
 
-PYBIND11_MODULE(_path, m, py::mod_gil_not_used())
+PYBIND11_MODULE(_path, m, py::mod_gil_not_used()
+#ifdef PYBIND11_HAS_SUBINTERPRETER_SUPPORT
+                ,py::multiple_interpreters::per_interpreter_gil()
+#endif
+)
 {
     m.def("point_in_path", &Py_point_in_path,
           "x"_a, "y"_a, "radius"_a, "path"_a, "trans"_a);

src/_qhull_wrapper.cpp

@@ -7,6 +7,9 @@
  */
 #include <pybind11/pybind11.h>
 #include <pybind11/numpy.h>
+#ifdef PYBIND11_HAS_SUBINTERPRETER_SUPPORT
+#include <pybind11/subinterpreter.h>
+#endif
 
 #ifdef _MSC_VER
 /* The Qhull header does not declare this as extern "C", but only MSVC seems to
@@ -276,7 +279,11 @@ delaunay(const CoordArray& x, const CoordArray& y, int verbose)
     return delaunay_impl(npoints, x.data(), y.data(), verbose == 0);
 }
 
-PYBIND11_MODULE(_qhull, m, py::mod_gil_not_used())
+PYBIND11_MODULE(_qhull, m, py::mod_gil_not_used()
+#ifdef PYBIND11_HAS_SUBINTERPRETER_SUPPORT
+                ,py::multiple_interpreters::per_interpreter_gil()
+#endif
+)
 {
     m.doc() = "Computing Delaunay triangulations.\n";
 

src/ft2font_wrapper.cpp

@@ -3,6 +3,9 @@
 #include <pybind11/native_enum.h>
 #include <pybind11/numpy.h>
 #include <pybind11/stl.h>
+#ifdef PYBIND11_HAS_SUBINTERPRETER_SUPPORT
+#include <pybind11/subinterpreter.h>
+#endif
 
 #include "ft2font.h"
 
@@ -1475,7 +1478,11 @@ ft2font__getattr__(std::string name) {
         "module 'matplotlib.ft2font' has no attribute {!r}"_s.format(name));
 }
 
-PYBIND11_MODULE(ft2font, m, py::mod_gil_not_used())
+PYBIND11_MODULE(ft2font, m, py::mod_gil_not_used()
+#ifdef PYBIND11_HAS_SUBINTERPRETER_SUPPORT
+                ,py::multiple_interpreters::per_interpreter_gil()
+#endif
+)
 {
     FT_Library ft2Library = nullptr;
 

src/tri/_tri_wrapper.cpp

@@ -1,8 +1,15 @@
 #include "_tri.h"
+#ifdef PYBIND11_HAS_SUBINTERPRETER_SUPPORT
+#include <pybind11/subinterpreter.h>
+#endif
 
 using namespace pybind11::literals;
 
-PYBIND11_MODULE(_tri, m, py::mod_gil_not_used())
+PYBIND11_MODULE(_tri, m, py::mod_gil_not_used()
+#ifdef PYBIND11_HAS_SUBINTERPRETER_SUPPORT
+                ,py::multiple_interpreters::per_interpreter_gil()
+#endif
+)
 {
     py::classh<Triangulation>(m, "Triangulation", py::is_final())
         .def(py::init<const Triangulation::CoordinateArray&,