Class: ThreadPool

Inherits:
Object
  • Object
show all
Defined in:
lib/threadpool.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(size) ⇒ ThreadPool

Creates a new ThreadPool with size threads, waiting at your beck and call.



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# File 'lib/threadpool.rb', line 9

def initialize(size)
  self.size  = size
  self.queue = Queue.new
  
  # create a pool of threads the size requested
  self.pool = Array.new(size) { thread }
end

Instance Attribute Details

#queue ⇒ Object

Returns the value of attribute queue.



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# File 'lib/threadpool.rb', line 3

def queue
  @queue
end

#size ⇒ Object

Returns the value of attribute size.



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# File 'lib/threadpool.rb', line 2

def size
  @size
end

Instance Method Details

#execute(*args, &job) ⇒ Object

Schedules a job to be run with the given args. Returns only once the queue of jobs to be performed is empty.

This is primarily intended for preventing front-loading an arbitraril large number of jobs into the queue. However, it works simply by calling Thread.pass until the queue is empty. This has the disadvantage of spinning the processor the all the threads are mostly waiting on I/O or sleeping. It also means that if other threads are scheduling jobs, this may never return.

Ideally, this method would pause the current thread until the job has begun execution, but this is surprisingly difficult to do with the Ruby built-in Queue class, which we use for the job queue.



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# File 'lib/threadpool.rb', line 39

def execute(*args, &job)
  self.schedule(*args, &job)
  
  Thread.pass until self.queue.empty?
end

#schedule(*args, &job) ⇒ Object

Schedules a job to be run with the given args. Returns immediately.



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# File 'lib/threadpool.rb', line 20

def schedule(*args, &job)
  self.queue.push [job, args]
end

#shutdown ⇒ Object

Cleans up after the ThreadPool, quitting and joining all remaining threads. No more jobs can be run in the pool once this method has been called.



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# File 'lib/threadpool.rb', line 50

def shutdown
  self.size.times { self.schedule { Thread.exit } }
  self.pool.each  {|thread| thread.join }
end