CODEWITHSUNDEEP
ruby-on-railscucumber
ardavis
ardavis

Reputation: 9895

Why is the first Rails request extremely slow in testing?

In Ruby on Rails, when I run the rails server, the very first request seems to be extremely slow, the logs show that the slowness comes from the view rendering:

2017-08-14 10:24:12.707 [ 22139] [INFO ] Completed 200 OK in 18547ms (Views: 18501.6ms | ActiveRecord: 3.7ms)

I assume it's because it needs to connect to the database. The next request is of course, fast(er):

2017-08-14 11:01:54.937 [ 25662] [INFO ] Completed 200 OK in 765ms (Views: 714.0ms | ActiveRecord: 8.3ms)

I assume this has something to do with the cache, and it already has a database connection. I've tried to restart my server, restart the database, clear my browser cache and rake db:sessions:clear, but I am unable to get the first request to go slow again in development.

Here's where things get interesting. Every single time I run the cucumber tests, the very first request is always incredibly slow:

2017-08-14 11:19:52.879 [ 27729] [INFO ] Completed 200 OK in 38326ms (Views: 38306.8ms | ActiveRecord: 6.1ms)

It's even longer than it is in development for unknown reasons.

What is different between restarting the Rails server and re-running a test that makes the first request of the tests so slow? What steps can I take to troubleshoot such an issue?

(It's no fun waiting 30 seconds every time we want to run one of our cucumber tests)

Upvotes: 3

Views: 515

Answers (1)

ardavis
ardavis

Reputation: 9895

Unfortunately the answer was extremely isolated to our code, but I wanted to share the answer in-case anyone else ever ran into this situation.

I noticed that if I ran rake tmp:cache:clear the first request in the browser would be really slow again. I investigated that command and saw it cleared out the #{Rails.root}/tmp directory.

I then found this line in the Cucumber env.rb:

Dir.foreach("#{Rails.root}/tmp") { |f|
  FileUtils.rm_rf("#{Rails.root}/tmp/#{f}")
}

That appeared to be the culprit the entire time. I don't know why that was added (3 years ago...)

Upvotes: 2

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