Rollbar 1.1.0->1.2.9 upgrade reduced performance

[gdeglin]

Hi. After upgrading to Rollbar 1.2.9 we noticed that NewRelic is reporting an additional 1ms being used by Rollbar that was not previously present. Admittedly this is not that much, but we have some API related actions that get called 300 times per second, so this adds up.

Here's a Newrelic graph with the red area starting after the 1.2.9 upgrade, and then ending after we downgraded back to 1.1.0.

[brianr]

Thanks @gdeglin . By chance do you have a more detailed trace available? I'm guessing the 1ms is taken up in fetch_scope:

https://github.com/rollbar/rollbar-gem/blob/master/lib/rollbar/middleware/rails/rollbar.rb#L36

but unclear which part of that is the bulk of the time.

[jondeandres]

This is cause since actually we get the current request data always and not only when there are errors, so it appears in the calling stack for each request, increasing a bit the response time.

It's only 1ms and probably not easy to improve it, but we can take a look :-).

[gdeglin]

@brianr Sorry, I don't have a more detailed trace than this. Sounds like @jondeandres is probably right about the problem though.

Thanks for taking a look! 1.1.0 is working fine, but I want to make sure we don't get caught off guard when you deprecate the old interface. An additional 1ms on all endpoints represents around 15% more CPU load for us.

[brianr]

Thanks @gdeglin.

@jondeandres perhaps we could gather the request context only when an error happens? Maybe this could be accomplished by having a proc that returns the scope, and then only call that proc when the data is needed.

[jondeandres]

@brianr we can try that solution yes. Actually we do something similar por person_data but not for request_data. Let's see how it works.

Update soon :-)

[brianr]

Hi @gdeglin -- we've pushed a change to master (8df754d) that should fix the performance issue.

Do you think you'd be able to try it in your environment and see if the performance is the same as in 1.1.0?

You can install it with:

gem 'rollbar', :git => 'git://github.com/rollbar/rollbar-gem.git', :ref => '8df754de95f10dec304a37845e38078c58265a8b'

[gdeglin]

@brianr Looks like the fix worked. Thanks!

[brianr]

Awesome, thanks for trying it out so quickly! We'll get this out in a new release soon.

[brianr]

Released in 1.3.0 (now up on rubygems). Thanks again!