[FIX] registry: make invalidation flags thread-specific

The registry attributes 'registry_invalidated' and 'cache_invalidated'
are used to flag that the current request has modified the registry or
invalidated the ormcache, respectively.  This provides a simple yet
efficient way to signal registry changes or cache invalidations to other
workers.

However, those flags were not meant to be used with multi-threaded
workers.  For instance, a thread may signal registry changes that are
actually made by another thread.  It can also happen that a thread
changes the registry, which makes another thread crash (like a thread
modifying a dict while another one iterates over it), and the latter
will reset the registry to its original state because it misinterprets
the registry changes as its own changes.

The situation can even get worse, making threads crash in cascade and
eventually leaving the registry in an inconsistent state.  When this
happens, the worker is broken and has to be manually restarted.

The fix consists in making those flags thread-specific.  This does not
prevent thread crashing because of concurrent changes, but at least it
avoids leaving the worker in a broken state.

closes odoo/odoo#77244

X-original-commit: cdbd315f
Signed-off-by: Raphael Collet (rco) <rco@openerp.com>

odoo/modules/registry.py

@@ -141,8 +141,7 @@ class Registry(Mapping):
         self.cache_sequence = None
 
         # Flags indicating invalidation of the registry or the cache.
-        self.registry_invalidated = False
-        self.cache_invalidated = False
+        self._invalidation_flags = threading.local()
 
         with closing(self.cursor()) as cr:
             self.has_unaccent = odoo.modules.db.has_unaccent(cr)
@@ -556,6 +555,24 @@ class Registry(Mapping):
 
         return model._table in self._ordinary_tables
 
+    @property
+    def registry_invalidated(self):
+        """ Determine whether the current thread has modified the registry. """
+        return getattr(self._invalidation_flags, 'registry', False)
+
+    @registry_invalidated.setter
+    def registry_invalidated(self, value):
+        self._invalidation_flags.registry = value
+
+    @property
+    def cache_invalidated(self):
+        """ Determine whether the current thread has modified the cache. """
+        return getattr(self._invalidation_flags, 'cache', False)
+
+    @cache_invalidated.setter
+    def cache_invalidated(self, value):
+        self._invalidation_flags.cache = value
+
     def setup_signaling(self):
         """ Setup the inter-process signaling on this registry. """
         if self.in_test_mode():