Run any code in parallel Processes(> use all CPUs) or Threads(> speedup blocking operations).
Best suited for map-reduce or e.g. parallel downloads/uploads.

Install

sudo gem install parallel

Usage

# 2 CPUs -> work in 2 processes (a,b + c)
results = Parallel.map(['a','b','c']) do |one_letter|
  expensive_calculation(letter)
end

# 3 Processes -> finished after 1 run
results = Parallel.map(['a','b','c'], :in_processes=>3){|one_letter| ... }

# 3 Threads -> finished after 1 run
results = Parallel.map(['a','b','c'], :in_threads=>3){|one_letter| ... }

Same can be done with each Parallel.each(['a','b','c']){|one_letter| ... } or each_with_index or map_with_index

Processes

• Speedup through multiple CPUs
• Speedup for blocking operations
• Protects global data
• Extra memory used ( very low on REE through copy_on_write_friendly )
• Child processes are killed when your main process is killed through Ctrl+c or kill -2

Threads

• Speedup for blocking operations
• Global data can be modified
• No extra memory used

Processes/Threads are workers, they grab the next piece of work when they finish

TODO

• JRuby / Windows support <-> possible ?

Authors

###Contributors (alphabetical)

• TJ Holowaychuk -- tj<$at$>vision-media.ca

Michael Grosser
grosser.michael@gmail.com
Hereby placed under public domain, do what you want, just do not hold me accountable...