[spark] Refine comment in Starting ray worker spark task (ray-project…

…#47670)

Signed-off-by: Weichen Xu <[email protected]>
Signed-off-by: ujjawal-khare <[email protected]>

python/ray/util/spark/cluster_init.py

@@ -1595,11 +1595,21 @@ def ray_cluster_job_mapper(_):
                 extra_env=ray_worker_node_extra_envs,
             )
         except Exception as e:
+            # In the following 2 cases, exception is raised:
+            # (1)
+            # Starting Ray worker node fails, the `e` will contain detail
+            # subprocess stdout/stderr output.
+            # (2)
             # In autoscaling mode, when Ray worker node is down, autoscaler will
             # try to start new Ray worker node if necessary,
-            # but we use spark job to launch Ray worker node process,
-            # to avoid trigger spark task retries, we swallow exception here
-            # to make spark task exit normally.
+            # and it creates a new spark job to launch Ray worker node process,
+            # note the old spark job will reschedule the failed spark task
+            # and raise error of "Starting Ray worker node twice with the same
+            # node id is not allowed".
+            #
+            # For either case (1) or case (2),
+            # to avoid Spark triggers more spark task retries, we swallow
+            # exception here to make spark the task exit normally.
             _logger.warning(f"Ray worker node process exit, reason: {repr(e)}.")
 
         yield 0