Python now inits from config and is isolated

src/runtime/Native/PyConfig.cs

@@ -0,0 +1,36 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Python.Runtime.Native;
+
+#pragma warning disable CS0169
+
+[StructLayout(LayoutKind.Sequential)]
+struct PyConfig
+{
+    int _config_init;
+    public int isolated;
+    int use_environment;
+    int dev_mode;
+    public int install_signal_handlers;
+
+    // Create an int array of size 256 as padding
+    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 1024)]
+    int[] padding;
+}
+
+public enum PyStatusType : int
+{
+    PyStatus_Ok,
+    PyStatus_Error,
+    PyStatus_Exception,
+    PyStatus_Exit
+}
+
+struct PyStatus
+{
+    public PyStatusType type;
+    IntPtr func;
+    IntPtr err_msg;
+    int exitcode;
+}

src/runtime/Runtime.Delegates.cs

@@ -281,6 +281,10 @@ static Delegates()
 
             PyType_Type = GetFunctionByName(nameof(PyType_Type), GetUnmanagedDll(_PythonDll));
             Py_NoSiteFlag = (int*)GetFunctionByName(nameof(Py_NoSiteFlag), GetUnmanagedDll(_PythonDll));
+
+            PyConfig_InitPythonConfig = (delegate* unmanaged[Cdecl]<out PyConfig, void>)GetFunctionByName(nameof(PyConfig_InitPythonConfig), GetUnmanagedDll(_PythonDll));
+            Py_InitializeFromConfig = (delegate* unmanaged[Cdecl]<ref PyConfig, PyStatus>)GetFunctionByName(nameof(Py_InitializeFromConfig), GetUnmanagedDll(_PythonDll));
+            PyConfig_Clear = (delegate* unmanaged[Cdecl]<ref PyConfig, void>)GetFunctionByName(nameof(PyConfig_Clear), GetUnmanagedDll(_PythonDll));
         }
 
         static global::System.IntPtr GetUnmanagedDll(string? libraryName)
@@ -540,5 +544,9 @@ static Delegates()
         internal static delegate* unmanaged[Cdecl]<int> _Py_IsFinalizing { get; }
         internal static IntPtr PyType_Type { get; }
         internal static int* Py_NoSiteFlag { get; }
+
+        internal static delegate* unmanaged[Cdecl]<out PyConfig, void> PyConfig_InitPythonConfig { get; }
+        internal static delegate* unmanaged[Cdecl]<ref PyConfig, PyStatus> Py_InitializeFromConfig { get; }
+        internal static delegate* unmanaged[Cdecl]<ref PyConfig, void> PyConfig_Clear { get; }
     }
 }

src/runtime/Runtime.cs

@@ -53,6 +53,8 @@ private static string GetDefaultDllName(Version version)
             return prefix + "python" + suffix + ext;
         }
 
+        private static PyConfig _configs = new PyConfig();
+
         private static bool _isInitialized = false;
         internal static bool IsInitialized => _isInitialized;
         private static bool _typesInitialized = false;
@@ -117,7 +119,7 @@ internal static void Initialize(bool initSigs = false)
             );
             if (!interpreterAlreadyInitialized)
             {
-                Py_InitializeEx(initSigs ? 1 : 0);
+                Py_InitializeFromConfig(initSigs ? 1 : 0);
 
                 NewRun();
 
@@ -144,6 +146,7 @@ internal static void Initialize(bool initSigs = false)
                     NewRun();
                 }
             }
+
             MainManagedThreadId = Thread.CurrentThread.ManagedThreadId;
 
             Finalizer.Initialize();
@@ -190,6 +193,21 @@ internal static void Initialize(bool initSigs = false)
             hexCallable = new(() => new PyString("%x").GetAttr("__mod__"));
         }
 
+        static void Py_InitializeFromConfig(int install_signal_handlers)
+        {
+            // Initialize PyConfig
+            Delegates.PyConfig_InitPythonConfig(out _configs);
+            _configs.isolated = 1;
+            _configs.install_signal_handlers = install_signal_handlers;
+
+            PyStatus status = Delegates.Py_InitializeFromConfig(ref _configs);
+            if (status.type != PyStatusType.PyStatus_Ok)
+            {
+                Delegates.PyConfig_Clear(ref _configs);
+                // Handle initialization error
+            }
+        }
+
         static void NewRun()
         {
             run++;
@@ -324,6 +342,8 @@ internal static void Shutdown()
             {
                 PyGILState_Release(state);
             }
+
+            Delegates.PyConfig_Clear(ref _configs);
         }
 
         const int MaxCollectRetriesOnShutdown = 20;