backport fix from #5712

changes.d/fix.5712.md

@@ -0,0 +1 @@
+Fixed a bug preventing simulation of task retries if `submission retry delays` unset.

cylc/flow/task_events_mgr.py

@@ -803,13 +803,13 @@ def _process_message_check(
                     f"[{itask}] "
                     f"{self.FLAG_RECEIVED_IGNORED}{message}{timestamp}"
                 )
-
-            else:
+                return False
+            elif flag == self.FLAG_POLLED_IGNORED:
                 LOG.warning(
                     f"[{itask}] "
                     f"{self.FLAG_POLLED_IGNORED}{message}{timestamp}"
                 )
-            return False
+                return False
 
         severity = cast(int, LOG_LEVELS.get(severity, INFO))
         # Demote log level to DEBUG if this is a message that duplicates what

cylc/flow/task_job_mgr.py

@@ -979,8 +979,8 @@ def _set_retry_timers(
             rtconfig = itask.tdef.rtconfig
 
         submit_delays = (
-            rtconfig['submission retry delays']
-            or itask.platform['submission retry delays']
+            rtconfig.get('submission retry delays', [])
+            or itask.platform.get('submission retry delays', [])
         )
 
         for key, delays in [

tests/functional/modes/03-simulation.t

@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+# THIS FILE IS PART OF THE CYLC WORKFLOW ENGINE.
+# Copyright (C) NIWA & British Crown (Met Office) & Contributors.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Test that simulation mode runs, and reruns a failed task successfully
+# when execution retry delays is configured.
+
+. "$(dirname "$0")/test_header"
+set_test_number 2
+
+install_workflow "${TEST_NAME_BASE}" "${TEST_NAME_BASE}"
+run_ok "${TEST_NAME_BASE}-validate" cylc validate "${WORKFLOW_NAME}"
+workflow_run_ok "${TEST_NAME_BASE}-run" \
+    cylc play \
+        --no-detach \
+        --mode=simulation \
+        --reference-test "${WORKFLOW_NAME}"
+purge
+exit

tests/functional/modes/03-simulation/flow.cylc

@@ -0,0 +1,16 @@
+[scheduler]
+    [[events]]
+        workflow timeout = PT30S
+
+[scheduling]
+    initial cycle point = 2359
+    [[graph]]
+        R1 = get_observations
+
+[runtime]
+    [[get_observations]]
+        execution retry delays = PT2S
+        [[[simulation]]]
+            fail cycle points = all
+            fail try 1 only = True
+

tests/functional/modes/03-simulation/reference.log

@@ -0,0 +1,2 @@
+23590101T0000Z/get_observations -triggered off [] in flow 1
+23590101T0000Z/get_observations -triggered off [] in flow 1