Export Python symbols globally for pymodule

phlex/app/load_module.cpp

@@ -18,6 +18,8 @@ using namespace std::string_literals;
 namespace phlex::experimental {
 
   namespace {
+    constexpr std::string_view pymodule_name{"pymodule"};
+
     // If factory function goes out of scope, then the library is unloaded...and that's
     // bad.
     std::vector<std::function<detail::module_creator_t>> create_module;
@@ -40,7 +42,11 @@ namespace phlex::experimental {
         std::filesystem::path shared_library_path{subdir};
         shared_library_path /= "lib" + spec + ".so";
         if (exists(shared_library_path)) {
-          return dll::import_alias<creator_t>(shared_library_path, symbol_name);
+          // Load pymodule with rtld_global to make Python symbols available to extension modules
+          // (e.g., NumPy). Load all other plugins with rtld_local (default) to avoid symbol collisions.
+          auto const load_mode =
+            (spec == pymodule_name) ? dll::load_mode::rtld_global : dll::load_mode::default_mode;
+          return dll::import_alias<creator_t>(shared_library_path, symbol_name, load_mode);
         }
       }
       throw std::runtime_error("Could not locate library with specification '"s + spec +
@@ -65,7 +71,7 @@ namespace phlex::experimental {
           }
           throw std::runtime_error(msg);
         }
-        raw_config["cpp"] = "pymodule";
+        raw_config["cpp"] = pymodule_name;
       }
 
       return raw_config;

plugins/python/CMakeLists.txt

@@ -18,7 +18,6 @@ add_library(
   src/errorwrap.cpp
 )
 target_link_libraries(pymodule PRIVATE phlex::module Python::Python Python::NumPy)
-
 target_compile_definitions(pymodule PRIVATE NPY_NO_DEPRECATED_API=NPY_1_7_API_VERSION)
 
 install(TARGETS pymodule LIBRARY DESTINATION lib)

plugins/python/src/pymodule.cpp

@@ -105,21 +105,6 @@ static bool initialize()
     return true;
   }
 
-  // TODO: the Python library is already loaded (b/c it's linked with
-  // this module), but its symbols need to be exposed globally to Python
-  // extension modules such as ctypes, yet this module is loaded with
-  // private visibility only. The workaround here locates the library and
-  // reloads (the handle is leaked b/c there's no knowing when it needs
-  // to be offloaded).
-  void* addr = dlsym(RTLD_DEFAULT, "Py_IsInitialized");
-  if (addr) {
-    Dl_info info;
-    if (dladdr(addr, &info) == 0 || info.dli_fname == 0 || info.dli_fname[0] == 0) {
-      throw std::runtime_error("unable to determine linked libpython");
-    }
-    dlopen(info.dli_fname, RTLD_GLOBAL | RTLD_NOW);
-  }
-
   PyConfig config;
   PyConfig_InitPythonConfig(&config);
   PyConfig_SetString(&config, &config.program_name, L"phlex");