CMFActivity: enable node preference by default in some safe cases

product/CMFActivity/ActiveObject.py

@@ -68,6 +68,8 @@ class ActiveObject(ExtensionClass.Base):
         - "same": prefer execution on this node, to make
                   better use of the ZODB Storage cache
         - "": no node preference
+        - None (default): let CMFActivity decide between the above 2 choice
+                          (see ActivityTool.activateObject)
 
       at_date           --  request execution date for this activate call
                             (default: date of commit)

product/CMFActivity/ActivityTool.py

@@ -91,6 +91,11 @@ _server_address = None
 ROLE_IDLE = 0
 ROLE_PROCESSING = 1
 
+# Activating a path means we tried to avoid loading useless
+# data in cache so there would be no gain to expect.
+# And all nodes are likely to have tools already loaded.
+NO_DEFAULT_NODE_PREFERENCE = str, BaseTool
+
 # Logging channel definitions
 import logging
 # Main logging channel
@@ -1205,14 +1210,25 @@ class ActivityTool (BaseTool):
         url = object.getPhysicalPath()
       if serialization_tag is not None:
         kw['serialization_tag'] = serialization_tag
-      if node is not None:
-        if node != 'same':
+      while 1: # not a loop
+        if node is None:
+          # The caller lets us decide whether we prefer to execute on same node
+          # (to increase the efficiency of the ZODB Storage cache).
+          if (isinstance(object, NO_DEFAULT_NODE_PREFERENCE)
+              # A grouped activity is the sign we may have many of them so make
+              # sure that this node won't overprioritize too many activities.
+              or kw.get('group_method_id', '') != ''):
+            break
+        elif node == '':
+          break
+        elif node != 'same':
           raise ValueError("Invalid node argument %r" % node)
         try:
           kw['node'] = 1 + self.getNodeList(
             role=ROLE_PROCESSING).index(getCurrentNode())
         except ValueError:
           pass
+        break
       return ActiveWrapper(self, url, oid, activity,
                            active_process, active_process_uid, kw,
                            getattr(self, 'REQUEST', None))

product/CMFActivity/tests/testCMFActivity.py

@@ -2490,7 +2490,7 @@ class TestCMFActivity(ERP5TypeTestCase, LogInterceptor):
 
     activities = 'SQLDict', 'SQLQueue'
     for activities in product(activities, activities):
-      for node, expected in (None, '21'), ("same", '12'):
+      for node, expected in (None, '12'), ('', '21'), ('same', '12'):
         o._setTitle('0')
         # The dance around getNodeDict is to simulate the creation of
         # activities from 2 different nodes. We also change title in 2