From 17e58ac70a0a0d4e89e987ffcf34ebe4247db2ab Mon Sep 17 00:00:00 2001
From: Victor Milovanov <lost@losttech.software>
Date: Tue, 23 Feb 2021 22:56:07 -0800
Subject: [PATCH] allow GIL state debugging; require GILState to be properly
 disposed

https://github.com/pythonnet/pythonnet/issues/1389#issuecomment-784716437
---
 src/runtime/pythonengine.cs | 26 +++++++++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)

diff --git a/src/runtime/pythonengine.cs b/src/runtime/pythonengine.cs
index 35ea3f6d2..bdacba4c1 100644
--- a/src/runtime/pythonengine.cs
+++ b/src/runtime/pythonengine.cs
@@ -4,6 +4,7 @@
 using System.Linq;
 using System.Reflection;
 using System.Runtime.InteropServices;
+using System.Threading;
 
 namespace Python.Runtime
 {
@@ -51,6 +52,9 @@ public static bool IsInitialized
             get { return initialized; }
         }
 
+        /// <summary>Set to <c>true</c> to enable GIL debugging assistance.</summary>
+        public static bool DebugGIL { get; set; } = false;
+
         internal static DelegateManager DelegateManager
         {
             get
@@ -668,7 +672,7 @@ public static GILState GIL()
                 PythonEngine.Initialize();
             }
 
-            return new GILState();
+            return PythonEngine.DebugGIL ? new DebugGILState() : new GILState();
         }
 
         public static PyScope CreateScope()
@@ -693,7 +697,7 @@ internal GILState()
                 state = PythonEngine.AcquireLock();
             }
 
-            public void Dispose()
+            public virtual void Dispose()
             {
                 if (this.isDisposed) return;
 
@@ -704,7 +708,23 @@ public void Dispose()
 
             ~GILState()
             {
-                Dispose();
+                throw new InvalidOperationException("GIL must always be released, and it must be released from the same thread that acquired it.");
+            }
+        }
+
+        public class DebugGILState : GILState
+        {
+            readonly Thread owner;
+            internal DebugGILState() : base()
+            {
+                this.owner = Thread.CurrentThread;
+            }
+            public override void Dispose()
+            {
+                if (this.owner != Thread.CurrentThread)
+                    throw new InvalidOperationException("GIL must always be released from the same thread, that acquired it");
+
+                base.Dispose();
             }
         }