ZODB Components: Fix deadlock between import lock and aq_method_lock.

product/ERP5Type/dynamic/component_package.py

@@ -241,25 +241,6 @@ class ComponentDynamicPackage(ModuleType):
     As per PEP-302, raise an ImportError if the Loader could not load the
     module for any reason...
     """
-    # In Python < 3.3, the import lock is a global lock for all modules:
-    # http://bugs.python.org/issue9260
-    #
-    # So, release the import lock acquired by import statement on all hooks to
-    # load objects from ZODB. When an object is requested from ZEO, it sends a
-    # RPC request and lets the asyncore thread gets the reply. This reply may
-    # be a tuple (PICKLE, TID), sent directly to the first thread, or an
-    # Exception, which tries to import a ZODB module and thus creates a
-    # deadlock because of the global import lock
-    #
-    # Also, handle the case where find_module() may be called without import
-    # statement as it does change anything in sys.modules
-    import_lock_held = True
-    try:
-      imp.release_lock()
-    except RuntimeError:
-      import_lock_held = False
-
-    try:
     site = getSite()
     name = fullname[len(self._namespace_prefix):]
 
@@ -327,15 +308,8 @@ class ComponentDynamicPackage(ModuleType):
     source_code_str = component.getTextContent(validated_only=True)
     version_package = self._getVersionPackage(version)
 
-    finally:
-      # Internal release of import lock at the end of import machinery will
-      # fail if the hook is not acquired
-      if import_lock_held:
-        imp.acquire_lock()
-
     # All the required objects have been loaded, acquire import lock to modify
     # sys.modules and execute PEP302 requisites
-    if not import_lock_held:
     imp.acquire_lock()
     try:
       # The module *must* be in sys.modules before executing the code in case
@@ -393,10 +367,6 @@ class ComponentDynamicPackage(ModuleType):
 
       return module
     finally:
-      # load_module() can be called outside of import machinery, for example
-      # to check first if the module can be handled by Component and then try
-      # to load it without going through the same code again
-      if not import_lock_held:
       imp.release_lock()
 
   def load_module(self, fullname):
@@ -404,8 +374,34 @@ class ComponentDynamicPackage(ModuleType):
     Make sure that loading module is thread-safe using aq_method_lock to make
     sure that modules do not disappear because of an ongoing reset
     """
-    with aq_method_lock:
+    # In Python < 3.3, the import lock is a global lock for all modules:
+    # http://bugs.python.org/issue9260
+    #
+    # So, release the import lock acquired by import statement on all hooks to
+    # load objects from ZODB. When an object is requested from ZEO, it sends a
+    # RPC request and lets the asyncore thread gets the reply. This reply may
+    # be a tuple (PICKLE, TID), sent directly to the first thread, or an
+    # Exception, which tries to import a ZODB module and thus creates a
+    # deadlock because of the global import lock
+    #
+    # Also, handle the case where find_module() may be called without import
+    # statement as it does change anything in sys.modules
+    import_lock_held = True
+    try:
+      imp.release_lock()
+    except RuntimeError:
+      import_lock_held = False
+
+    aq_method_lock.acquire()
+    try:
       return self.__load_module(fullname)
+    finally:
+      aq_method_lock.release()
+
+      # Internal release of import lock at the end of import machinery will
+      # fail if the hook is not acquired
+      if import_lock_held:
+        imp.acquire_lock()
 
   def find_load_module(self, name):
     """