From e2557c83a833371546ed93a33d1547e0871b1ebe Mon Sep 17 00:00:00 2001
From: Frederic Devernay <frederic.devernay@m4x.org>
Date: Tue, 6 Jul 2021 16:47:57 -0700
Subject: [PATCH] AppManager: fix Python interpreter

- GIL must be acquired before calling Py_Main
- Py_Main releases it for us
- Py_Main calls Py_Finalize for us
---
 Engine/AppManager.cpp | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/Engine/AppManager.cpp b/Engine/AppManager.cpp
index 4d4c341660..05be6613d2 100644
--- a/Engine/AppManager.cpp
+++ b/Engine/AppManager.cpp
@@ -3411,6 +3411,10 @@ AppManager::tearDownPython()
 
     return;
 #endif
+    if ( !Py_IsInitialized() ) {
+        return;
+    }
+
     ///See https://web.archive.org/web/20150918224620/http://wiki.blender.org/index.php/Dev:2.4/Source/Python/API/Threads
 #if !defined(NDEBUG)
     QThread* curThread = QThread::currentThread();
@@ -3499,14 +3503,19 @@ AppManager::launchPythonInterpreter()
         throw std::runtime_error("AppInstance::launchPythonInterpreter(): interpretPythonScript(" + s + " failed!");
     }
 
-    PythonGILLocker pgl;
+    PyGILState_Ensure(); // Py_Main does PyGILState_Release() for us.
+
+    assert(PyThreadState_Get());
+#if PY_VERSION_HEX >= 0x030400F0
+    assert(PyGILState_Check()); // Not available prior to Python 3.4
+#endif
+
 #if PY_MAJOR_VERSION >= 3
     // Python 3
     Py_Main(1, &_imp->commandLineArgsWide[0]);
 #else
     Py_Main(1, &_imp->commandLineArgsUtf8[0]);
 #endif
-
 }
 
 int