fibur.markdown

Fibur

Fibur is a library that allows concurrency during Ruby I/O operations without needing to make use of callback systems. Traditionally in Ruby, to achieve concurrency during blocking I/O operations, programmers would make use of Fibers and callbacks. Fibur eliminates the need for wrapping your I/O calls with Fibers and a callback. It allows you to write your blocking I/O calls the way you normally would, and still have concurrent execution during those I/O calls.

Example

Say you have a method that fetches data from a network resource:

require 'net/http'
def network_read uri
  Net::HTTP.get_response uri
end

We need to fetch that data say 100 times, so we'll wrap it in a loop:

100.times { network_read }

If we benchmark this code:

require 'benchmark'
require 'net/http'
require 'uri'

def network_read(uri)
  Net::HTTP.get_response uri
end

n = 50000
uri = URI('http://google.com/')

Benchmark.bm do |x|
  x.report('loop') { 100.times { network_read(uri) } }
end

On my machine it takes about 5 seconds:

$ ruby test.rb
       user     system      total        real
loop  0.210000   0.070000   0.280000 (  5.731776)

Now lets modify our benchmark to wrap each call to network_read in a Fibur:

require 'benchmark'
require 'net/http'
require 'uri'
require 'fibur' # use the Fibur gem.

def network_read(uri)
  Net::HTTP.get_response uri
end

n = 50000
uri = URI('http://google.com/')

Benchmark.bm(5) do |x|
  x.report('loop') { 100.times { network_read(uri) } }
  x.report('fibur') {
    100.times.map {
      Fibur.new { network_read(uri) }
    }.map(&:join)
  }
end

Output from our benchmark:

$ ruby -I. test.rb
            user     system      total        real
loop    0.220000   0.070000   0.290000 (  5.732683)
fibur   0.110000   0.050000   0.160000 (  0.197434)

Wrapping each call to network_read in a fibur brought the time down to 0.2 seconds! Using Fiburs, we were able to gain full concurrency during our I/O operations, and we didn't have to modify our network_read method.

Installation

Fibur only works on Ruby 1.9, and you can get it by installing the fibur gem.

How does it work?

I encourage you to check out the source.