Improve stall logic

Occasionally, the suite can be marked as stalled, even though the task
pool only contains succeeded tasks. This change fixes the problem.

lib/cylc/task_pool.py

@@ -797,15 +797,21 @@ def warn_stop_orphans(self):
 
     def pool_is_stalled(self):
         """Return True if no active, queued or clock trigger awaiting tasks"""
+        can_be_stalled = False
         for itask in self.get_tasks():
             if itask.point > self.stop_point:
                 # Don't consider task beyond stop point
                 continue
+            if itask.state.status in [
+                    TASK_STATUS_SUCCEEDED, TASK_STATUS_EXPIRED]:
+                # Succeeded and expired tasks don't stall the suite
+                continue
             if itask.state.status in TASK_STATUSES_NOT_STALLED or (
                     not itask.start_time_reached() and
                     itask.state.status not in TASK_STATUSES_FINAL):
                 return False
-        return True
+            can_be_stalled = True
+        return can_be_stalled
 
     def report_stalled_task_deps(self):
         """Return a set of unmet dependencies"""

tests/events/31-dont-stall-succeeded.t

@@ -0,0 +1,38 @@
+#!/bin/bash
+# THIS FILE IS PART OF THE CYLC SUITE ENGINE.
+# Copyright (C) 2008-2017 NIWA
+# 
+# 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 no stall when task pool has succeeded tasks only.
+. "$(dirname "$0")/test_header"
+set_test_number 4
+
+install_suite "${TEST_NAME_BASE}" "${TEST_NAME_BASE}"
+run_ok "${TEST_NAME_BASE}-validate" cylc validate "${SUITE_NAME}"
+run_ok "${TEST_NAME_BASE}-run" cylc run "${SUITE_NAME}"
+TIMEOUT=$(($(date +%s) + 60))
+while (($(date +%s) < TIMEOUT)) && \
+    ! grep -q '\[t1\.1\] .* succeeded' "${SUITE_RUN_DIR}/log/suite/log"
+do
+    sleep 1
+done
+grep_ok '\[t1\.1\] .* succeeded' "${SUITE_RUN_DIR}/log/suite/log"
+
+sleep 5
+cylc stop --max-polls=10 --interval=2 "${SUITE_NAME}" 1>'/dev/null' 2>&1
+run_fail "${TEST_NAME_BASE}-stall" \
+    grep -q -F 'WARNING - suite stalled' "${SUITE_RUN_DIR}/log/suite/log"
+purge_suite "${SUITE_NAME}"
+exit

tests/events/31-dont-stall-succeeded/suite.rc

@@ -0,0 +1,13 @@
+#!jinja2
+[cylc]
+    disable automatic shutdown = True
+    [[events]]
+        abort on stalled = True
+        abort on inactivity = True
+        inactivity = PT1M
+[scheduling]
+    [[dependencies]]
+        graph=t1
+[runtime]
+    [[t1]]
+        script = true