[Mono-bugs] [Bug 65414][Nor] Changed - [PATCH] Thread Local Data Slots do not survive nested appdomain transitions

bugzilla-daemon@bugzilla.ximian.com bugzilla-daemon@bugzilla.ximian.com
Tue, 7 Sep 2004 15:00:04 -0400 (EDT)

Please do not reply to this email- if you want to comment on the bug, go to the
URL shown below and enter your comments there.

Changed by bmaurer@users.sf.net.


--- shadow/65414	2004-09-07 14:19:18.000000000 -0400
+++ shadow/65414.tmp.4634	2004-09-07 15:00:04.000000000 -0400
@@ -129,6 +129,55 @@
 Do you have an idea where the ThreadStatic values are stored?
 Apparently not: they are stored in a field pointed to by the Thread
 object. So it is no different having the hash as a direct field in
 MonoThread or having it as a field of a field which is what using
 ThreadStatic makes it become. If you see different behaviour there is
 some other bug or you didn't test properly.
+------- Additional Comments From bmaurer@users.sf.net  2004-09-07 15:00 -------
+There is a huge difference.
+Fields are assigned a slot in
+MonoVTable *
+mono_class_vtable (MonoDomain *domain, MonoClass *class)
+In this method there is the following code:
+                        gint32 special_static = 
+field_is_special_static (class, field);
+                        if (special_static != SPECIAL_STATIC_NONE) {
+                                guint32 size, align, offset;
+                                size = mono_type_size (field->type, 
+                                offset = 
+mono_alloc_special_static_data (special_static, size, align);
+                                if (!domain->special_static_fields)
+                                        domain->special_static_fields 
+= g_hash_table_new (NULL, NULL);
+                                g_hash_table_insert (domain-
+>special_static_fields, field, GUINT_TO_POINTER (offset));
+                                continue;
+                        }
+So ThreadStatic fields are per-appdomain, per-thread. This is very 
+different from fields in the Thread class which are only per-thread, 
+they are shared across appdomains.
+A good blog on this is here:
+By default, static fields are scoped to AppDomains.  In other words, 
+each AppDomain gets its own copy of all the static fields for the 
+types that are loaded into that AppDomain.  This is independent of 
+whether the code was loaded as domain-neutral or not.  Loading code 
+as domain neutral affects whether we can share the code and certain 
+other runtime structures.  It is not supposed to have any effect 
+other than performance.
+Static fields marked with System.ThreadStaticAttribute are scoped per-
+thread per-AppDomain.  You get convenient declarative thread-local 
+storage over and above the normal per-AppDomain cloning of static