[GitHub] ashb commented on a change in pull request #4516: [AIRFLOW-2524] Handle StopIteration in CloudWatch logs retrieval

[GitBox <gi...@apache.org>]

ashb commented on a change in pull request #4516: [AIRFLOW-2524] Handle StopIteration in CloudWatch logs retrieval
URL: https://github.com/apache/airflow/pull/4516#discussion_r247428826
 
 

 ##########
 File path: airflow/contrib/hooks/sagemaker_hook.py
 ##########
 @@ -304,7 +304,15 @@ def multi_stream_iter(self, log_group, streams, positions=None):
         positions = positions or {s: Position(timestamp=0, skip=0) for s in streams}
         event_iters = [self.log_stream(log_group, s, positions[s].timestamp, positions[s].skip)
                        for s in streams]
-        events = [next(s) if s else None for s in event_iters]
+        events = []
+        for s in event_iters:
+            if not s:
+                events.append(None)
+                continue
+            try:
+                events.append(next(s))
+            except StopIteration:
+                events.append(None)
 
 Review comment:
   This seems.... odd to me. StopIteration inside a `for` loop should already be handled:
   
   
   ```python
   def mkiter():
       yield 1
       yield 2
       yield 3
       raise StopIteration()
   
   for a in mkiter():
       print(a)
   print("done")
   ```
   
   When run:
   
   ```python
   >>> def mkiter():
   ...     yield 1
   ...     yield 2
   ...     yield 3
   ...     raise StopIteration()
   ...
   >>> mkiter()
   <generator object mkiter at 0x10b9d9308>
   >>> for a in mkiter():
   ...     print(a)
   ...
   1
   2
   3
   >>> print("done")
   done
   ```

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