Do not add producer that has been added by saver

strax/context.py

@@ -1006,7 +1006,7 @@ def _get_end_targets(plugins: dict) -> ty.Tuple[str]:
         """Get the datatype that is provided by a plugin but not depended on by any other plugin."""
         provides = [prov for p in plugins.values() for prov in strax.to_str_tuple(p.provides)]
         depends_on = [dep for p in plugins.values() for dep in strax.to_str_tuple(p.depends_on)]
-        uniques = list(set(provides) ^ set(depends_on))
+        uniques = list(set(provides) - set(depends_on))
         return strax.to_str_tuple(uniques)
 
     @property
@@ -1310,7 +1310,8 @@ def concat_loader(*args, **kwargs):
         if len(intersec):
             raise RuntimeError(f"{intersec} both computed and loaded?!")
         if len(targets) > 1:
-            final_plugin = [t for t in targets if t in self._get_end_targets(plugins)][:1]
+            pendants = set(targets) & set(self._get_end_targets(plugins))
+            final_plugin = tuple(pendants - set(loaders))[:1]
             self.log.warning(
                 "Multiple targets detected! This is only suitable for mass "
                 f"producing dataypes since only {final_plugin} will be "

strax/processors/post_office.py

@@ -113,7 +113,12 @@ def state(self):
         result.append(f"Total time spent: {sum(self.time_spent.values())}")
         return "\n".join(result)
 
-    def register_producer(self, iterator: ty.Iterator[ty.Any], topic: ty.Union[str, ty.Tuple[str]]):
+    def register_producer(
+        self,
+        iterator: ty.Iterator[ty.Any],
+        topic: ty.Union[str, ty.Tuple[str]],
+        registered: ty.Tuple[str, ...] = tuple(),
+    ):
         """Register iterator as the source of messages for topic.
 
         If topic is a tuple of strings, the iterator should produce (topic -> message) dicts, with
@@ -128,7 +133,8 @@ def register_producer(self, iterator: ty.Iterator[ty.Any], topic: ty.Union[str,
                 # Multi-output producer, recurse
                 for sub_topic in topic:
                     self._multi_output_topics[sub_topic] = topic
-                    self.register_producer(iterator, sub_topic)
+                    if sub_topic not in registered:
+                        self.register_producer(iterator, sub_topic)
                 return
         assert isinstance(topic, str)
         if topic in self._producers:

strax/processors/single_thread.py

@@ -35,9 +35,12 @@ def __init__(
                 continue
             plugins_seen.append(p)
 
+            # Some data_types might be already saved and can be loaded;
+            # remove them from the list of provides
             self.post_office.register_producer(
                 p.iter(iters={dep: self.post_office.get_iter(dep, d) for dep in p.depends_on}),
                 topic=strax.to_str_tuple(p.provides),
+                registered=tuple(components.loaders),
             )
 
         dtypes_built = {d: p for p in components.plugins.values() for d in p.provides}