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https://github.com/SamSaffron/memory_profiler

memory_profiler for ruby
https://github.com/SamSaffron/memory_profiler

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memory_profiler for ruby

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[![CI](https://github.com/SamSaffron/memory_profiler/actions/workflows/ci.yml/badge.svg)](https://github.com/SamSaffron/memory_profiler/actions/workflows/ci.yml)

[![Gem Version](https://badge.fury.io/rb/memory_profiler.svg)](https://rubygems.org/gems/memory_profiler)



# MemoryProfiler



A memory profiler for Ruby



## Requirements



Ruby(MRI) Version 3.1.0 and above.



## Installation



Add this line to your application's Gemfile:



    gem 'memory_profiler'



And then execute:



    $ bundle



Or install it yourself as:



    $ gem install memory_profiler



## Usage



There are two ways to use `memory_profiler`:

* command line

* convenience API



### Command Line



The easiest way to use memory_profiler is via the command line, which requires no modifications to your program. The basic usage is:



```

$ ruby-memory-profiler [options] run [--] command [command-options]

```



Example:



```

$ ruby-memory-profiler --pretty run -- rubocop --cache false



$ ruby-memory-profiler --max=10 --pretty run -- ruby notify_users.rb 1 2 3 --quiet

```



For a full list of options, execute the following command:



```

$ ruby-memory-profiler -h

```



### Convenience API



```ruby

require 'memory_profiler'

report = MemoryProfiler.report do

  # run your code here

end



report.pretty_print

```



Or, you can use the `.start`/`.stop` API as well:



```ruby

require 'memory_profiler'



MemoryProfiler.start



# run your code



report = MemoryProfiler.stop

report.pretty_print

```



**NOTE:**  `.start`/`.stop` can only be run once per report, and `.stop` will

be the only time you can retrieve the report using this API.



## Options



### `report`



The `report` method can take a few options:



* `top`: maximum number of entries to display in a report (default is 50)

* `allow_files`: include only certain files from tracing - can be given as a String, Regexp, or array of Strings

* `ignore_files`: exclude certain files from tracing - can be given as a String or Regexp

* `trace`: an array of classes for which you explicitly want to trace object allocations



Check out `Reporter#new` for more details.



```

pry> require 'memory_profiler'

pry> MemoryProfiler.report(allow_files: 'rubygems'){ require 'mime-types' }.pretty_print

Total allocated 82375

Total retained 22618



allocated memory by gem

-----------------------------------

rubygems x 305879



allocated memory by file

-----------------------------------

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb x 285433

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/basic_specification.rb x 18597

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems.rb x 2218

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/specification.rb x 1169

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/defaults.rb x 520

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_gem.rb x 80

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/version.rb x 80



. . .

```



### `pretty_print`



The `pretty_print` method can take a few options:



* `to_file`: a path to your log file - can be given a String

* `color_output`: a flag for whether to colorize output - can be given a Boolean

* `retained_strings`: how many retained strings to print - can be given an Integer

* `allocated_strings`: how many allocated strings to print - can be given a Integer

* `detailed_report`: should report include detailed information - can be given a Boolean

* `scale_bytes`: flag to convert byte units (e.g. 183200000 is reported as 183.2 MB, rounds with a precision of 2 decimal digits) - can be given a Boolean

* `normalize_paths`: flag to remove a gem's directory path from printed locations - can be given a Boolean

*Note: normalized path of a "location" from Ruby's stdlib will be prefixed with `ruby/lib/`. e.g.: `ruby/lib/set.rb`, `ruby/lib/pathname.rb`, etc.*



Check out `Results#pretty_print` for more details.



For example to report to file, use `pretty_print` method with `to_file` option and `path_to_your_log_file` string:

```

$ pry

pry> require 'memory_profiler'

pry> MemoryProfiler.report(allow_files: 'rubygems'){ require 'mime-types' }.pretty_print(to_file: 'path_to_your_log_file')



$ less my_report.txt

Total allocated 82375

Total retained 22618



allocated memory by gem

-----------------------------------

rubygems x 305879



. . .

```



## Example Session



You can easily use memory_profiler to profile require impact of a gem, for example:



```

pry> require 'memory_profiler'

pry> MemoryProfiler.report{ require 'mime-types'  }.pretty_print

Total allocated 82375

Total retained 22618



allocated memory by gem

-----------------------------------

mime-types-2.0 x 3668277

2.1.0-github/lib x 2035704

rubygems x 305879

other x 40



allocated memory by file

-----------------------------------

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb x 3391763

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb x 2021853

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb x 285433

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types/loader.rb x 227033

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types/cache.rb x 48663

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/basic_specification.rb x 18597

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/x86_64-linux/json/ext/parser.so x 8200

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/x86_64-linux/json/ext/generator.so x 2463

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems.rb x 2218

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/specification.rb x 1169

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/defaults.rb x 520

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types/loader_path.rb x 417

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/version.rb x 409

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types.rb x 361

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/generic_object.rb x 241

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/ext.rb x 200

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json.rb x 120

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_gem.rb x 80

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/version.rb x 80

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime-types.rb x 40

(pry) x 40



allocated memory by location

-----------------------------------

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb:155 x 1985709

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:522 x 927503

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:632 x 827676

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:302 x 499525

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:625 x 281047

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:521 x 265920

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:629 x 265920

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:523 x 265920

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55 x 222705

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types/loader.rb:215 x 218105

[REDACTED]



allocated]objects by gem

-----------------------------------

mime-types-2.0 x 56564

2.1.0-github/lib x 22210

rubygems x 3600

other x 1



allocated objects by file

-----------------------------------

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb x 56237

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb x 21978

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb x 3388

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types/cache.rb x 291

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/basic_specification.rb x 169

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/x86_64-linux/json/ext/parser.so x 124

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems.rb x 53

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/x86_64-linux/json/ext/generator.so x 37

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/specification.rb x 26

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types/loader.rb x 24

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/defaults.rb x 13

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/version.rb x 7

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types.rb x 6

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types/loader_path.rb x 5

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/ext.rb x 5

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json.rb x 3

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/generic_object.rb x 3

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_gem.rb x 2

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/version.rb x 2

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime-types.rb x 1

(pry) x 1



allocated objects by location

-----------------------------------

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:522 x 21337

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb:155 x 21095

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:632 x 9972

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:523 x 6648

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:521 x 6648

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:629 x 6648

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55 x 3307

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:302 x 2955

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:625 x 1663

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb:60 x 837

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:224 x 312

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types/cache.rb:62 x 287

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/x86_64-linux/json/ext/parser.so:0 x 124

[REDACTED]



retained memory by gem

-----------------------------------

mime-types-2.0 x 1496813

2.1.0-github/lib x 519954

rubygems x 76195



retained memory by file

-----------------------------------

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb x 1447316

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb x 516679

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb x 75946

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types/cache.rb x 48583

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/x86_64-linux/json/ext/generator.so x 2263

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/x86_64-linux/json/ext/parser.so x 892

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types/loader.rb x 577

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types/loader_path.rb x 297

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/basic_specification.rb x 169

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/specification.rb x 80

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types.rb x 40

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/generic_object.rb x 40

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/ext.rb x 40

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/version.rb x 40



retained memory by location

-----------------------------------

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb:155 x 516181

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:302 x 499525

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:632 x 414007

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:625 x 280878

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:629 x 132960

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:523 x 66480

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:135 x 58151

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:224 x 52728

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types/cache.rb:62 x 48503

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55 x 17795

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/x86_64-linux/json/ext/generator.so:0 x 2263

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/x86_64-linux/json/ext/parser.so:0 x 892

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types/loader.rb:239 x 577

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types/loader_path.rb:15 x 257

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/basic_specification.rb:124 x 169

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb:122 x 89

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:46 x 89

[REDUCTED]



retained objects by gem

-----------------------------------

mime-types-2.0 x 15211

2.1.0-github/lib x 7089

rubygems x 318



retained objects by file

-----------------------------------

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb x 14918

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb x 7045

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb x 315

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types/cache.rb x 289

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/x86_64-linux/json/ext/generator.so x 32

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/x86_64-linux/json/ext/parser.so x 9

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/specification.rb x 2

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types/loader_path.rb x 2

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types/loader.rb x 1

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types.rb x 1

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/version.rb x 1

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/generic_object.rb x 1

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/ext.rb x 1

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/basic_specification.rb x 1



retained objects by location

-----------------------------------

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb:155 x 7035

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:632 x 4987

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:629 x 3324

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:302 x 2955

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:625 x 1662

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:523 x 1662

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:224 x 312

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55 x 300

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/types/cache.rb:62 x 287

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/x86_64-linux/json/ext/generator.so:0 x 32

/home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:135 x 15

[REDUCTED]



Allocated String Report

-----------------------------------

"application" x 12050

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:522 x 4820

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:521 x 2410

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:632 x 2410

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:629 x 2410

"" x 6669

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:522 x 6648

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55 x 11

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:266 x 4

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb:71 x 1

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb:72 x 1

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb:69 x 1

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:0 x 1

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_gem.rb:39 x 1

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb:70 x 1

"/" x 3342

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:523 x 3324

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55 x 13

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb:60 x 4

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:135 x 1

"encoding" x 3336

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb:155 x 3324

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55 x 10

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:135 x 1

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb:60 x 1

"registered" x 3328

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb:155 x 3324

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55 x 4

"content-type" x 3327

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb:155 x 3324

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55 x 3

"references" x 2944

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb:155 x 2940

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55 x 4

"IANA" x 2824

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb:155 x 1412

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:302 x 1412

[REDUCTED]



Retained String Report

-----------------------------------

"IANA" x 2824

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb:155 x 1412

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:302 x 1412

"application" x 2410

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:632 x 1205

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:629 x 1205

"base64" x 1527

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/json/common.rb:155 x 1525

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:70 x 1

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55 x 1

"audio" x 300

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:632 x 150

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:629 x 150

"video" x 188

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:632 x 94

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:629 x 94

"text" x 155

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:629 x 77

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/gems/2.1.0/gems/mime-types-2.0/lib/mime/type.rb:632 x 77

    /home/sam/.rbenv/versions/2.1.0-github/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55 x 1

[REDUCTED]



```



The data is also available in the MemoryProfiler::Results object returned.



### Retained vs Allocated



The report breaks down 2 key concepts.



**Retained**: long lived memory use and object count retained due to the execution of the code block.



**Allocated**: All object allocation and memory allocation during code block.



As a general rule "retained" will always be smaller than or equal to allocated.



Memory profiler will tell you aggregate costs of the above, for example requiring the mime-types gem above results in approx 2MB of retained memory in 22K or so objects. The actual RSS cost will always be slightly higher as MRI heaps are not squashed to size and memory fragments. In future we may be able to calculate a rough long term GC cost of retained objects (for major GCs).



Memory profiler also performs some String analysis to help you find strings that would heavily benefit from #freeze. In the example above the string IANA is retained in memory 2824 times, this costs you a minimum of RVALUE_SIZE (40 on x64) * 2824.



## Contributing



1. Fork it

2. Create your feature branch (`git checkout -b my-new-feature`)

3. Commit your changes (`git commit -am 'Add some feature'`)

4. Push to the branch (`git push origin my-new-feature`)

5. Create new Pull Request