free

(C) John Mair (banisterfiend) 2010

force immediate garbage collection of Ruby objects

free provides the Object#free method enabling a user to garbage collect an object on demand and free all its internal structures.

free also has rubygems-test support; to participate, first install free, then:

  1. Install rubygems-test: gem install rubygems-test
  2. Run the test: gem test free
  3. Finally choose 'Yes' to upload the results.

Example: Freeing a String

Let's free a String:

hello = "hello world"
id = hello.object_id

hello.free

# Note we go through the id as accessing the freed object directly
# may cause a segfault
ObjectSpace._id2ref(id) #=> RangeError: _id2ref': 0x1c1a63c is recycled object

Example: Destructors

Free also supports object destructors. If the __destruct__ method is implemented on the object being freed it will be called before freeing takes place; and the return value of free will be the return value of __destruct__:

o = Object.new
def o.__destruct__
  :killed
end

o.free #=> :killed

Features and limitations

Features

  • Can free any object (but be careful, see below)
  • Works in both Ruby 1.8 and 1.9.
  • Some protection from freeing critical objects and immediate values.
  • Supports object destructors
  • Can free multiple objects at same time, e.g: Free.free a, b, c

Limitations

  • Beta software, beware.
  • Supports MRI and YARV only.
  • Not complete protection from freeing silly things, e.g core classes. Be sensible :)
  • Can be dangerous - free will force garbage collection on an object
  • even if references to it still exist. Trying to access an already
  • freed object may result in unexpected behaviour or segfaults.

Caveats

Benchmarks have shown that free can significantly improve performance, but only when the objects you free are very large (approximately > 10K in size).

It is not recommended you free small or medium-sized objects as you will actually negatively impact performance - as the free process itself incurs some overhead.

In general you should benchmark your application with and without free before you decide to use it.

Contact

Problems or questions contact me at github

Special Thanks

Coderrr for the idea

License

(The MIT License)

Copyright (c) 2011 (John Mair)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.