Cancel scheduled tasks when cogs unload

When cogs reload, they used new Scheduler instances, which aren't aware
of previously scheduled tasks. This led to duplicate scheduled tasks
when cogs re-scheduled tasks upon initialisation.

Fixes #1080
Fixes BOT-7H

1 files changed, 4 insertions, 0 deletions

diff --git a/bot/cogs/reminders.py b/bot/cogs/reminders.py
index b5998cc0e..670493bcf 100644
--- a/bot/cogs/reminders.py
+++ b/bot/cogs/reminders.py
@@ -37,6 +37,10 @@ class Reminders(Cog):
 
         self.bot.loop.create_task(self.reschedule_reminders())
 
+    def cog_unload(self) -> None:
+        """Cancel scheduled tasks."""
+        self.scheduler.cancel_all()
+
     async def reschedule_reminders(self) -> None:
         """Get all current reminders from the API and reschedule them."""
         await self.bot.wait_until_guild_available()