Got a Ruby heap dump? Great. Use this tool to see what's in it!
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Latest commit e21be68 Dec 30, 2017

Heapy (Ruby Heap Dump Inspector)

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A CLI for analyzing Ruby Heap dumps. Thanks to Sam Saffron for the idea and initial code.


Add this line to your application's Gemfile:

gem 'heapy'

And then execute:

$ bundle

Or install it yourself as:

$ gem install heapy


Step 1) Generate a heap dump. You could do this manually. Or you can use a tool like derailed_benchmarks

Step 2) Once you've got the heap dump, you can analyze it using this CLI:

$ heapy read tmp/2015-10-01T10:18:59-05:00-heap.dump

Generation: nil object count: 209191
Generation:  14 object count: 407
Generation:  15 object count: 638
Generation:  16 object count: 748
Generation:  17 object count: 1023
Generation:  18 object count: 805
# ...

NOTE: The reason you may be getting a "nil" generation is these objects were loaded into memory before your code began tracking the allocations. To ensure all allocations are tracked you can execute your ruby script this trick. First create a file trace.rb that only starts allocation tracing:

# trace.rb
require 'objspace'


Now make sure this command is loaded before you run your script, you can use Ruby's -I to specify a load path and -r to specify a library to require, in this case our trace file

$ ruby -I ./ -r trace script_name.rb

If the last line of your file is invalid JSON, make sure that you are closing the file after writing the ruby heap dump to it.

Digging into a Generation

You can drill down into a specific generation. In the previous example, the 17'th generation looks strangely large, you can drill into it:

$ heapy read tmp/2015-10-01T10:18:59-05:00-heap.dump 17
    Analyzing Heap (Generation: 17)

    allocated by memory (44061517) (in bytes)
      39908512  /app/vendor/ruby-2.2.3/lib/ruby/2.2.0/timeout.rb:79
       1284993  /app/vendor/ruby-2.2.3/lib/ruby/2.2.0/openssl/buffering.rb:182
        201068  /app/vendor/bundle/ruby/2.2.0/gems/json-1.8.3/lib/json/common.rb:223
        189272  /app/vendor/bundle/ruby/2.2.0/gems/newrelic_rpm-
        172531  /app/vendor/ruby-2.2.3/lib/ruby/2.2.0/net/http/header.rb:172
         92200  /app/vendor/bundle/ruby/2.2.0/gems/activesupport-4.2.3/lib/active_support/core_ext/numeric/conversions.rb:131

Reviewing all generations

If you want to read all generations you can use the "all" directive

$ heapy read tmp/2015-10-01T10:18:59-05:00-heap.dump all

You can also use T-Lo's online JS based Heap Analyzer for visualizations.


After checking out the repo, run $ bundle install to install dependencies. Then, run rake spec to run the tests.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to


Bug reports and pull requests are welcome on GitHub at This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.


The gem is available as open source under the terms of the MIT License.