Merge branch 'master' into string-marshaling-cache

pythonnet · dmitriyse · Aug 31, 2017 · Sep 2, 2017 · Sep 2, 2017 · Sep 2, 2017
commit ffceeed7f6ba2aad398d7c00d22539f5dfb3b2d3
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -29,7 +29,7 @@ This document follows the conventions laid out in [Keep a CHANGELOG][].
 
 -   Fixed secondary PythonEngine.Initialize call, all sensitive static variables now reseted.
     This is a hidden bug. Once python cleaning up enough memory, objects from previous engine run becomes corrupted.
--   Fixed Visual Studio 2017 compat (#434) for setup.py
+-   Fixed Visual Studio 2017 compat ([#434][i434]) for setup.py
 -   Fixed crash on exit of the Python interpreter if a python class
     derived from a .NET class has a `__namespace__` or `__assembly__`
     attribute ([#481][i481])

diff --git a/src/runtime/assemblymanager.cs b/src/runtime/assemblymanager.cs
@@ -17,8 +17,16 @@ internal class AssemblyManager
     {
         // modified from event handlers below, potentially triggered from different .NET threads
         // therefore this should be a ConcurrentDictionary
+        //
+        // WARNING: Dangerous if cross-app domain usage is ever supported
+        //    Reusing the dictionary with assemblies accross multiple initializations is problematic. 
+        //    Loading happens from CurrentDomain (see line 53). And if the first call is from AppDomain that is later unloaded, 
+        //    than it can end up referring to assemblies that are already unloaded (default behavior after unload appDomain - 
+        //     unless LoaderOptimization.MultiDomain is used);
+        //    So for multidomain support it is better to have the dict. recreated for each app-domain initialization
         private static ConcurrentDictionary<string, ConcurrentDictionary<Assembly, string>> namespaces =
             new ConcurrentDictionary<string, ConcurrentDictionary<Assembly, string>>();
+
         //private static Dictionary<string, Dictionary<string, string>> generics;
         private static AssemblyLoadEventHandler lhandler;
         private static ResolveEventHandler rhandler;