add comment

python/instrumentation/openinference-instrumentation-llama-index/src/openinference/instrumentation/llama_index/_callback.py

@@ -390,6 +390,10 @@ def __setitem__(self, key: _EventId, value: _EventData) -> None:
         if key not in self and len(self) >= self._capacity > 0:
             # pop the oldest straggler by insertion order
             _, event_data = self.popitem(last=False)
+            # FIXME: It's unclear whether we should call `_finish_tracing` here or just drop
+            # the event data, and if we call finish tracing, what status we should set it to?
+            # Note that calling `_finish_tracing` here sets the `end_time` to now because
+            # stragglers have no `end_time` (their `on_event_end` has not been called).
             _finish_tracing(event_data)
         super().__setitem__(key, value)