Adds sentinel return value to prevent sweeper from crashing (facebook…

…research#2479)

plugins/hydra_submitit_launcher/hydra_plugins/hydra_submitit_launcher/config.py

@@ -29,6 +29,8 @@ class BaseQueueConf:
     stderr_to_stdout: bool = False
 
     # If True, the launcher will not wait for the job to finish (useful for very long runs)
+    # This value is not passed to submitit, it is used by the launcher itself. When enabled,
+    # a set of sentinel values are returned to the sweeper to indicate that the job is running.
     no_block: bool = False
 
 

plugins/hydra_submitit_launcher/hydra_plugins/hydra_submitit_launcher/submitit_launcher.py

@@ -5,7 +5,13 @@
 from typing import Any, Dict, List, Optional, Sequence
 
 from hydra.core.singleton import Singleton
-from hydra.core.utils import JobReturn, filter_overrides, run_job, setup_globals
+from hydra.core.utils import (
+    JobReturn,
+    filter_overrides,
+    run_job,
+    setup_globals,
+    JobStatus,
+)
 from hydra.plugins.launcher import Launcher
 from hydra.types import HydraContext, TaskFunction
 from omegaconf import DictConfig, OmegaConf, open_dict
@@ -145,7 +151,8 @@ def launch(
         jobs = executor.map_array(self, *zip(*job_params))
 
         if self.no_block:
-            return []
+            sentinal = JobReturn(status=JobStatus.COMPLETED, _return_value=None)
+            return [sentinal] * num_jobs
         else:
             return [j.results()[0] for j in jobs]