From dabada88421a54a13507570a75bfc80b9ba5218c Mon Sep 17 00:00:00 2001
From: Ronnie Dutta <61982285+MetRonnie@users.noreply.github.com>
Date: Mon, 7 Dec 2020 11:16:54 +0000
Subject: [PATCH 1/3] Fix failure to shutdown on keyboard interrupt

---
 cylc/flow/scheduler.py     | 4 ++--
 cylc/flow/scheduler_cli.py | 8 +-------
 2 files changed, 3 insertions(+), 9 deletions(-)

diff --git a/cylc/flow/scheduler.py b/cylc/flow/scheduler.py
index fd546fec9e0..b07a06d9f3b 100644
--- a/cylc/flow/scheduler.py
+++ b/cylc/flow/scheduler.py
@@ -611,7 +611,7 @@ async def start_scheduler(self):
             await self.shutdown(exc)
             raise exc from None
 
-        except Exception as exc:
+        except (KeyboardInterrupt, asyncio.CancelledError, Exception) as exc:
             try:
                 await self.shutdown(exc)
             except Exception as exc2:
@@ -643,7 +643,7 @@ async def run(self):
             await self.configure()
             await self.start_servers()
             await self.log_start()
-        except Exception as exc:
+        except (KeyboardInterrupt, asyncio.CancelledError, Exception) as exc:
             await self.shutdown(exc)
             raise
         else:
diff --git a/cylc/flow/scheduler_cli.py b/cylc/flow/scheduler_cli.py
index fbfa04bf584..f5dbe2d3e27 100644
--- a/cylc/flow/scheduler_cli.py
+++ b/cylc/flow/scheduler_cli.py
@@ -406,13 +406,7 @@ async def _run(parser, options, reg, is_restart, scheduler):
     # stop cylc stop
     except SchedulerError:
         ret = 1
-    except KeyboardInterrupt as exc:
-        try:
-            await scheduler.shutdown(exc)
-        except Exception as exc2:
-            # In case of exceptions in the shutdown method itself.
-            LOG.exception(exc2)
-            raise exc2 from None
+    except (KeyboardInterrupt, asyncio.CancelledError):
         ret = 2
     except Exception:
         ret = 3

From d0e5dd2f99976df7d9900930554179ca289ae66e Mon Sep 17 00:00:00 2001
From: Ronnie Dutta <61982285+MetRonnie@users.noreply.github.com>
Date: Mon, 7 Dec 2020 11:30:31 +0000
Subject: [PATCH 2/3] Update changelog

---
 CHANGES.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/CHANGES.md b/CHANGES.md
index 7d76a08419c..7acb057fe55 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -164,6 +164,10 @@ task outputs/message triggers are now validated.
 workflow in a sub-directory of a run directory (as `cylc scan` would not be
 able to find it).
 
+[#3982](https://github.com/cylc/cylc-flow/pull/3982) - Fix bug preventing
+workflow from shutting down properly on a keyboard interrupt (Ctrl+C) in
+Python 3.8+.
+
 -------------------------------------------------------------------------------
 ## __cylc-8.0a2 (2020-07-03)__
 

From 7cfb0ec3f72f70952513e18dafea62198b9a16d0 Mon Sep 17 00:00:00 2001
From: Ronnie Dutta <61982285+MetRonnie@users.noreply.github.com>
Date: Mon, 7 Dec 2020 20:23:44 +0000
Subject: [PATCH 3/3] Ensure any exceptions are logged properly in
 scheduler.run()

---
 cylc/flow/scheduler.py | 34 +++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/cylc/flow/scheduler.py b/cylc/flow/scheduler.py
index b07a06d9f3b..25dac4df33f 100644
--- a/cylc/flow/scheduler.py
+++ b/cylc/flow/scheduler.py
@@ -612,12 +612,7 @@ async def start_scheduler(self):
             raise exc from None
 
         except (KeyboardInterrupt, asyncio.CancelledError, Exception) as exc:
-            try:
-                await self.shutdown(exc)
-            except Exception as exc2:
-                # In case of exceptions in the shutdown method itself
-                LOG.exception(exc2)
-            raise exc from None
+            await self.handle_exception(exc)
 
         else:
             # main loop ends (not used?)
@@ -644,8 +639,7 @@ async def run(self):
             await self.start_servers()
             await self.log_start()
         except (KeyboardInterrupt, asyncio.CancelledError, Exception) as exc:
-            await self.shutdown(exc)
-            raise
+            await self.handle_exception(exc)
         else:
             # note start_scheduler handles its own shutdown logic
             await self.start_scheduler()
@@ -1619,16 +1613,19 @@ async def shutdown(self, reason):
 
         """
         if isinstance(reason, SchedulerStop):
-            LOG.info('Suite shutting down - %s', reason.args[0])
+            LOG.info(f'Suite shutting down - {reason.args[0]}')
         elif isinstance(reason, SchedulerError):
-            LOG.error('Suite shutting down - %s', reason)
+            LOG.error(f'Suite shutting down - {reason}')
         elif isinstance(reason, SuiteConfigError):
             LOG.error(f'{SuiteConfigError.__name__}: {reason}')
         elif isinstance(reason, PlatformLookupError):
             LOG.error(f'{PlatformLookupError.__name__}: {reason}')
         else:
             LOG.exception(reason)
-            LOG.critical('Suite shutting down - %s', reason)
+            if str(reason):
+                LOG.critical(f'Suite shutting down - {reason}')
+            else:
+                LOG.critical('Suite shutting down')
 
         if self.proc_pool:
             self.proc_pool.close()
@@ -1836,3 +1833,18 @@ def process_cylc_stop_point(self):
         if stoppoint is not None:
             self.options.stopcp = str(stoppoint)
             self.pool.set_stop_point(get_point(self.options.stopcp))
+
+    async def handle_exception(self, exc):
+        """Gracefully shut down the scheduler.
+
+        This re-raises the caught exception, to be caught higher up.
+
+        Args:
+            exc: The caught exception to be logged during the shutdown.
+        """
+        try:
+            await self.shutdown(exc)
+        except Exception as exc2:
+            # In case of exceptions in the shutdown method itself
+            LOG.exception(exc2)
+        raise exc from None