fixed crash in finalizer of CLR types defined in Python, that survive engine shutdown (pythonnet#1260)

lostmsu · web-flow · commit e2ab3ae4fd55 · 2020-12-18T13:30:06.000+01:00
pythonnet#1256 pythonnet#1256 During engine shutdown all links from Python to .NET instances are severed. If an instance of CLR class defined in Python survives the shutdown (for example, a reference is stored in static field) and later gets finalized, it will attempt to severe link again, which is an invalid operation. The fix is to check if the link has already been severed and skip that step during finalization.
diff --git a/src/runtime/classderived.cs b/src/runtime/classderived.cs
@@ -858,7 +858,7 @@ public static void Finalize(IPythonDerivedType obj)
             {
                 if (0 == Runtime.Py_IsInitialized() || Runtime.IsFinalizing)
                 {
-                    self.gcHandle.Free();
+                    if (self.gcHandle.IsAllocated) self.gcHandle.Free();
                     return;
                 }
             }
@@ -873,7 +873,7 @@ public static void Finalize(IPythonDerivedType obj)
                     // If python's been terminated then just free the gchandle.
                     if (0 == Runtime.Py_IsInitialized() || Runtime.IsFinalizing)
                     {
-                        self.gcHandle.Free();
+                        if (self.gcHandle.IsAllocated) self.gcHandle.Free();
                         return;
                     }
 

Original file line number	Diff line number	Diff line change
`@@ -858,7 +858,7 @@ public static void Finalize(IPythonDerivedType obj)`
`858`	`858`	`{`
`859`	`859`	`if (0 == Runtime.Py_IsInitialized() \|\| Runtime.IsFinalizing)`
`860`	`860`	`{`
`861`		`- self.gcHandle.Free();`
	`861`	`+ if (self.gcHandle.IsAllocated) self.gcHandle.Free();`
`862`	`862`	`return;`
`863`	`863`	`}`
`864`	`864`	`}`
`@@ -873,7 +873,7 @@ public static void Finalize(IPythonDerivedType obj)`
`873`	`873`	`// If python's been terminated then just free the gchandle.`
`874`	`874`	`if (0 == Runtime.Py_IsInitialized() \|\| Runtime.IsFinalizing)`
`875`	`875`	`{`
`876`		`- self.gcHandle.Free();`
	`876`	`+ if (self.gcHandle.IsAllocated) self.gcHandle.Free();`
`877`	`877`	`return;`
`878`	`878`	`}`
`879`	`879`