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Ruby Performance Tools

Update: We now offer a hosted metrics service for Ruby developers which can give you useful feedback about your code. Check out Caliper, to get started with metrics for your project.

I have been interested in all of the tools that exist for Ruby developers. I give you the first of a series of posts where I will be looking at some of the more interesting Ruby tools.

Recently a few different Rail performance tools / web services have been released. They are leaps and bounds better than just watching your developer log and trying to fix performance issues, or just tracking down slow MySQL queries. I went ahead and installed and worked with a few of these tools and wrote a bit about my thoughts and experience with each of them.


ruby-prof does what every other profiler does, but it is much faster than the one built in to Ruby. It also makes it easy to output the information you are seeking to HTML pages, such as call graphs. If you are just looking for a simple write up to get started with ruby-prof I recommend the previous link. I will talk a little more about the kinds of problems I find and how I have solved them with ruby-prof.

I have used ruby-prof a number of times to isolate the ways to speed up my code. I haven’t used it to identify why an entire Rails application is slow (there are better tools I discuss later for that), but if you have a small but highly important piece of code ruby-prof is often the best way to isolate the problem. I used ruby-prof to identified the two slowest lines of code of a spellchecker, which was rewritten to become twice as fast.

Most recently I used it to identify where the code was spending all of its time in a loop for a file syncer. It turns out that for thousands of files each time through the loop we were continually calling over and over. Putting a small cache around that call essentially eliminated all delays in our file synchronization. Below is a simple example of how a few lines of code can make all the difference in performance and how easily ruby-prof can help you isolate the problem areas and where to spend your time. I think seeing the code that ruby-prof helped isolate, and the changes made to the code might be useful if you are new to profiling and performance work.

changes in our spellchecker / recommender

 #OLD Way
 alteration = []
    n.times {|i| LETTERS.each_byte {
        |l| alteration << word[0...i].strip+l.chr+word[i+1..-1].strip } }
 insertion = []
     (n+1).times {|i| LETTERS.each_byte {
        |l| insertion << word[0...i].strip+l.chr+word[i..-1].strip } }
 #NEW Way
    #pre-calculate the word breakups
    word_starts = []
    word_missing_ends = []
    word_ends = []
    (n+1).times do |i|
      word_starts << word[0...i]
      word_missing_ends << word[i+1..-1]
      word_ends << word[i..-1]

 alteration = []
    n.times {|i|
      alteration = alteration.concat LETTERS.collect { |l|
        word_starts[i]+l+word_missing_ends[i] } }
 insertion = []
    (n+1).times {|i|
      insertion = insertion.concat LETTERS.collect { |l|

        word_starts[i]+l+word_ends[i] } }

Changes in our file syncer

 path_name =
 path_name = get_relative_path(path)

  def get_relative_path(path)
    return @path_cache[path] if @path_cache.member?(path)
    retval =
    @path_cache[path] = retval
    return retval

New Relic

New Relic is a performance monitoring tool for Rails apps. It has a great development mode that will help you track down performance issues before they even become a problem, and live monitoring so that you can find any hiccups that are slowing down the production application. The entire performance monitoring space for Ruby/Rails seems to be heating up. I guess it is easy to see why, when scaling has been such an issue for some Rails apps. Just playing around with New Relic was exciting and fun. I could quickly track down the slowest pages, and our most problematic SQL calls, in this case I was testing New Relic on Seekler (an old project of ours) since I didn’t think I would find much interesting on our current Devver site. Seekler had some glaring performance issues and I think if we had New Relic from the beginning we could have avoided many of them. Sounds like I might have a day project involving New Relic and giving Seekler as much of a performance boost as possible. New Relic turned out to be my favorite of the performance monitoring tools. For a much more detailed writeup check out RailsTips New Relic Review.

newrelic screenshot
New Relic screenshot


TuneUp another easy-to-install and use Rails performance monitoring solution. The problem I had with TuneUp was I couldn’t get it working on test app for these sorts of things. I tried running Seekler with TuneUp, but had no luck. I found that many people on the message boards seemed to be having various compatibility issues. I looked at the TuneUp screencast and the kind of information that they give you and I feel like this would be equal to New Relic if it works for you. I am emailing back and forth with FiveRuns support who have been very attentive and helpful, so if I get it working I will update this section.

Ruby Run

RubyRun provides live performance monitoring and debugging tools. I hadn’t ever heard of this product before I started doing some research while writing this blog article. I am sorry to say but this was the hardest to set up, and gave back less valuable information. I think they need a simple screencast on how to get set up and get useful information back. After getting setup and running I could only get ugly CSV reports that didn’t tell me much more than the regular Rails log files. I started reading the RubyRun Manual but it was about as long as Moby Dick and all I wanted was how to view simple easy-to-read reports which is a snap in New Relic and TuneUp. Since the site didn’t mention RubyRun providing better data than New Relic or TuneUp which were much more user friendly, I don’t think I would recommend RubyRun.

UPDATE: After reading about my difficulties with RubyRun the great folks from Rubysophic got in touch with me. They offered to help me get the tool working and posted a RubyRun quick start guide to their site. I got it working in a snap thanks to an email from their dev and the amazingly simple quick start guide. I still didn’t get the same depth of information that I got with New Relic, although RubyRun has a ton of settings so it is likely you can get more depth to the reports. Something worth pointing out is that RubyRun is working on Seekler, which I haven’t been able to get TuneUp running on. So if you have been having problems with TuneUp or New Relic, definitely give RubyRun a look. In the end I think the other offerings are slightly more user friendly (less complex settings), and easier to explore the data (link in the feed to both reports, at least when in developer mode). That being said RubyRun offers some great information and options that the others don’t and with a bit more UI tuning RubyRun would be at the top of the pack. Thanks to the helpful devs at Rubysophic for helping me to get the most out of RubyRun.

RubyRun screenshot
RubyRun screenshot
RubyRun second screen shot
screenshot of a different RubyRun report

If there are any other Ruby performance tools worth checking out let me know. Obviously, if you have experience with any of these tools I would love to hear your thoughts on them.


Written by DanM

September 28, 2008 at 2:35 pm

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  1. […] Ruby Performance Tools […]

  2. […] He then gives a brief but well written overview of each of four of the existing Rails Performance Management tools. Take a look here […]

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