Set execution polling delays correctly

CHANGES.md

@@ -42,6 +42,10 @@ workflow source argument), and rename the `--flow-name` option to
 
 ### Fixes
 
+[#4844](https://github.com/cylc/cylc-flow/pull/4844) - Fixes bug where
+execution polling intervals used in combination with an execution time limit
+resulted in incorrect polling intervals.
+
 [#4829](https://github.com/cylc/cylc-flow/pull/4829) -
 Suppress deprecated configuration warnings in Cylc 7 compatibility mode.
 

cylc/flow/task_events_mgr.py

@@ -1511,13 +1511,15 @@ def _reset_job_timers(self, itask):
                 if not time_limit_delays:
                     time_limit_delays = [60, 120, 420]
                 timeout = time_limit + sum(time_limit_delays)
-                # Remove excessive polling before time limit
-                while sum(delays) > time_limit:
-                    del delays[-1]
-                # But fill up the gap before time limit
-                if delays:
-                    size = int((time_limit - sum(delays)) / delays[-1])
-                    delays.extend([delays[-1]] * size)
+                if sum(delays) > time_limit:
+                    # Remove excessive polling before time limit
+                    while sum(delays) > time_limit:
+                        del delays[-1]
+                else:
+                    # Fill up the gap before time limit
+                    if delays:
+                        size = int((time_limit - sum(delays)) / delays[-1])
+                        delays.extend([delays[-1]] * size)
                 time_limit_delays[0] += time_limit - sum(delays)
                 delays += time_limit_delays
         else:  # if itask.state.status == TASK_STATUS_SUBMITTED:

tests/functional/execution-time-limit/04-polling-intervals.t

@@ -0,0 +1,59 @@
+#!/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 execution time limit works correctly with polling intervals
+
+. "$(dirname "$0")/test_header"
+set_test_number 6
+
+init_workflow "${TEST_NAME_BASE}" << __FLOW__
+[scheduling]
+    [[graph]]
+        R1 = nolimit & limit95M & limit1H  & limit10M & limit70S
+[runtime]
+    [[root]]
+        script = "echo Hello"
+        execution polling intervals = 3*PT30S, PT10M, PT1H
+    [[nolimit]]
+    [[limit95M]]
+        execution time limit = PT95M
+    [[limit1H]]
+        execution time limit = PT1H
+    [[limit10M]]
+        execution time limit = PT10M
+    [[limit70S]]
+        execution time limit = PT70S
+__FLOW__
+
+run_ok "${TEST_NAME_BASE}-validate" cylc validate "${WORKFLOW_NAME}"
+
+cylc play "${WORKFLOW_NAME}"
+
+poll_grep_workflow_log "INFO - DONE"
+
+# NOTE: execution timeout polling is delayed by PT1M to let things settle
+# PT10M = (3*PT3S + PT9M30S) - PT1M
+grep_workflow_log_ok grep-limit10M "\[1/limit10M running job:01 flows:1\] health: execution timeout=PT20M, polling intervals=3\*PT30S,PT9M30S,PT2M,PT7M,..."
+# PT60M = (3*PT3S + PT10M + PT49M30S) - PT1M
+grep_workflow_log_ok grep-limit1H "\[1/limit1H running job:01 flows:1\] health: execution timeout=PT1H10M, polling intervals=3\*PT30S,PT10M,PT49M30S,PT2M,PT7M,..."
+# PT70S = (2*PT30S + PT1M10S) - PT1M
+grep_workflow_log_ok grep-limit70S "\[1/limit70S running job:01 flows:1\] health: execution timeout=PT11M10S, polling intervals=2\*PT30S,PT1M10S,PT2M,PT7M,..."
+# PT95M = (3*PT3S + PT10M + PT1H + PT24M30S) - PT1M
+grep_workflow_log_ok grep-limit95M "\[1/limit95M running job:01 flows:1\] health: execution timeout=PT1H45M, polling intervals=3\*PT30S,PT10M,PT1H,PT24M30S,PT2M,PT7M,..."
+grep_workflow_log_ok grep-no-limit "\[1/nolimit running job:01 flows:1\] health: execution timeout=None, polling intervals=3\*PT30S,PT10M,PT1H,..."
+
+purge