rebaseline_server: periodically log tasks_queue size

gm/rebaseline_server/compare_rendered_pictures.py

Index: gm/rebaseline_server/compare_rendered_pictures.py
diff --git a/gm/rebaseline_server/compare_rendered_pictures.py b/gm/rebaseline_server/compare_rendered_pictures.py
index 1207979f535d39f80431197d83d39bbff2601302..d5460f446122f45b48511e654a0270ca575432ac 100755
--- a/gm/rebaseline_server/compare_rendered_pictures.py
+++ b/gm/rebaseline_server/compare_rendered_pictures.py
@@ -206,6 +206,9 @@ class RenderedPicturesComparisons(results.BaseComparisons):
             results.KEY__RESULT_TYPE__NOCOMPARISON,
         ])
 
+    logging.info('Starting to add imagepairs to queue.')
+    self._image_diff_db.log_queue_size_if_changed(limit_verbosity=False)
+
     union_dict_paths = sorted(set(setA_dicts.keys() + setB_dicts.keys()))
     num_union_dict_paths = len(union_dict_paths)
     dict_num = 0
@@ -266,6 +269,9 @@ class RenderedPicturesComparisons(results.BaseComparisons):
             if result_type != results.KEY__RESULT_TYPE__SUCCEEDED:
               failing_image_pairs.add_image_pair(one_imagepair)
 
+    logging.info('Finished adding imagepairs to queue.')
+    self._image_diff_db.log_queue_size_if_changed(limit_verbosity=False)
+
     if self._prefetch_only:
       return None
     else: