Tuesday Session 4: Digging Deep with ActiveSupport::Notifications

Presenter: Matt Sanders @nextmat

What get measured gets managed

production != development
when problem happens you can already to be tracking the problem areas

Performance Monitoring

action controller request time
total request vs slow requests

SQL Monitoring

check requests by model

What to with data

custom logging - adding things to logger - pappertrail
custom event in New Relic
StatsD
KISS
save data for later - postpone sql explains

Performance

all subsribers are run in same thread as request
background slow subscribers

Power Moves

Conditional Instrumentation
- rollout
- turn on specific notifications for specific users
Simplifying Repetitive Instrumentation
- extend Forwardable
- LogSubscriber

Use Outside of Rails

activesupport/notifications can be on it's own
gems that use this
- faraday
- excon
what else can you do
- lograge
  - detactes existing log subscribers
- harness
- search rails for .instrument

Discuss Conventions for team

put subscribers in intializer
don't use for core events use for notifications

Take aways

what are the important things for our apps
what are our important metrics, what's the top 2
student action notifications