Bot fails to gracefully shut down

[ruthgrace]

The bot does not necessarily shut down gracefully. Here is an example from when reconnection after Slack team migration fails.

2016-08-28 03:43:52,136 Bot WARNING: Slack has initiated a team migration to a new server.  Attempting to reconnect...
2016-08-28 03:43:52,237 requests.packages.urllib3.connectionpool INFO: Starting new HTTPS connection (1): slack.com
2016-08-28 03:43:52,326 requests.packages.urllib3.connectionpool DEBUG: "POST /api/rtm.start HTTP/1.1" 200 64
2016-08-28 03:43:52,329 requests.packages.urllib3.connectionpool INFO: Starting new HTTP connection (1): localhost
2016-08-28 03:43:52,331 Webserver WARNING: Shutdown code received.  Stopping webserver...
2016-08-28 03:43:52,331 werkzeug INFO: 127.0.0.1 - - [28/Aug/2016 03:43:52] "POST /_/shutdown HTTP/1.1" 200 -
2016-08-28 03:43:52,331 requests.packages.urllib3.connectionpool DEBUG: "POST /_/shutdown HTTP/1.1" 200 0

After this, the docker container was not shut down, circumventing automatic restart.

[arcticfoxnv]

This is most likely due to a plugin starting a thread and not stopping it when the bot shuts down. Python won't force background threads to exit when the main thread exits.

[balajijegan]

https://docs.python.org/3/library/threading.html#threading.Thread.daemon

Why not set all plugins as daemon threads? The only downside is lock or any other operation the thread might be doing.

[arcticfoxnv]

Mostly because the bot was written with 2.7 in mind. At the time, python 3 wasn't a viable choice for our environment, and bot frameworks at the time were written for python 3. Additionally, existing frameworks didn't handle saving their config+state to anywhere other than local storage, which was a non-starter for the project.

Given python 2.7 is going away soon, everything should be python 3 anyways, and there are much better bot frameworks for python 3 than this one, I'm not sure how much time you would want to spend on rewriting the plugin system.

[balajijegan]

This issue is now resolved and we have not seen this issue after the python 3 rewrite and fixes that @amckenna-pinterest did.