optionally avoid Sidekiq::Stats#fetch_stats!

[adamvduke]

#9 adds the option to not report global sidekiq stats, but still initializes a Sidekiq::Stats instance which makes the calls to redis. The Sidekiq::Stats instance should only be initialized if the sidekiq_stats option is true.

[phstc]

@nhocki do you mind reviewing it? 🍻

I don't have a Sidekiq + StatsD setup to test it right now. 🐼

[adamvduke]

I also did some testing and noticed that the change didn't have a significant impact on the timings that get reported to statsd. It seems that is because fetching the stats is currently outside the scope of the timer. The middleware doesn't seem to be reporting how long it takes for a worker to run in total. It only reports how long the #perform method takes. Is that something that should be changed?

[adamvduke]

This is an identical set of 100000 jobs that just sleep for 0.03 seconds each with the only difference being changing the initializer from true to false. The second batch processed 7 minutes faster, and roughly 50% more jobs processed per time interval. Also note, ~75% drop in redis operations.

[phstc]

@adamvduke thanks. Added to master 🍻

[adamvduke]

🍻