Following code review, better docstring and take the lock less often

theano/gof/cmodule.py

@@ -1268,8 +1268,11 @@ class ModuleCache(object):
     """
 
     def clear_old(self, age_thresh_del=None, delete_if_problem=False):
-        """
-        Delete entries from the filesystem for cache entries that are too old.
+        """Delete entries from the filesystem for cache entries that are too old.
+
+        This refreshes the content of the cache. Don't hold the lock
+        while calling this method, this is useless. It will be taken
+        if needed.
 
         Parameters
         ----------
@@ -1380,12 +1383,17 @@ class ModuleCache(object):
                                         to_rename, to_delete)
 
     def clear_unversioned(self, min_age=None):
-        """
-        Delete unversioned dynamic modules.
+        """Delete unversioned dynamic modules.
 
         They are deleted both from the internal dictionaries and from the
         filesystem.
 
+        No need to have the lock when calling this method. It does not
+        take the lock as unversioned module aren't shared.
+
+        This method does not refresh the cache content, it just
+        accesses the in-memory known module(s).
+
         Parameters
         ----------
         min_age
@@ -1471,9 +1479,7 @@ class ModuleCache(object):
                     if age > min_age:
                         to_del.append(os.path.join(self.dirname, filename))
 
-        if not to_del:
-            return
-        with compilelock.lock_ctx():
+        # No need to take the lock as it isn't shared.
         for f in to_del:
             _rmtree(f,
                     msg='old unversioned', level=logging.INFO,