tunemygc doesn't sync with puma

[leonsp]

ruby 2.4.4p296 (2018-03-28 revision 63013) [x86_64-linux]
Using rails 4.2.10
Using tunemygc 1.0.71

TuneMyGC seems to start:

# bundle exec rails s -b 0.0.0.0 -p 8080
[tunemygc] Rails detected, loading railtie
=> Booting Puma
=> Rails 4.2.10 application starting in development on http://0.0.0.0:8080
=> Run `rails server -h` for more startup options
=> Ctrl-C to shutdown server
Setting Rails logger to STDOUT
Configuring Sentry
I, [2018-05-23T16:32:00.792099 #44]  INFO -- sentry: ** [Raven] Raven 2.3.1 ready to catch errors
I, [2018-05-23T16:32:01.476954 #44]  INFO -- sentry: ** [Raven] Raven 2.3.1 ready to catch errors
Puma starting in single mode...
* Version 3.11.4 (ruby 2.4.4-p296), codename: Love Song
* Min threads: 0, max threads: 16
* Environment: development
* Listening on tcp://0.0.0.0:8080
Use Ctrl-C to stop

But it doesn't sync when I Ctrl-C out of the process:

^C- Gracefully stopping, waiting for requests to finish
=== puma shutdown: 2018-05-23 16:33:26 +0000 ===
- Goodbye!
Exiting

Is there something I can do to force it to sync?