ThreadPool

ThreadPool is a class that you can instantiate to build a pool of running threads. The threads wait on a Ruby Queue object for jobs - in the form of ruby blocks or lambdas - to perform.

ThreadPool was written with the intention of being used on JRuby but will work on other rubies too especially Ruby 1.9+. Note: At the moment no effort has been made to patch Ruby 1.8.* for any threading issues.

Send errors or issues to: Daniel Bush < dlb.id.au -at- gmail.com >

Basic Workflow

ThreadPool uses a dispatch method with a block for putting jobs in the queue to be processed asynchronously:

# Create 5 threads
tp = ThreadPool.new(5)

# Dispatch an asynchronous task.
tp.dispatch do
  # your task
end

# Wait for all threads to finish
tp.join

Or lambdas/procs

func = lambda { ... your task ... }
tp.dispatch func

In fact as long as it responds to call you're probably ok.

You can also pass arguments to dispatch and they will be handed to the block when it is taken from the queue:

tp.dispatch(foo, bar) do |foo, bar|
  print "foo: #{foo}; bar: #{bar}\n"
end

…or in the case of a Proc:

my_proc = Proc.new { |foo, bar| print "foo: #{foo}; bar: #{bar}\n" }
tp.dispatch(my_proc, foo, bar)

At the moment it's assumed that you won't try to handle or modify thread control within the task itself.

You can add or remove threads from the thread pool using ThreadPool#increment and ThreadPool#decrement. These methods haven't been fully tested yet.

ThreadPool also has a SyncQueue class which represents a single queue and a single thread that synchronously executes the jobs in this queue. You can instantiate one of these and it will run separate to the thread pool. To be honest I'm not sure why you need it but I was looking at the Grand Central Dispatch technique which seemed to have a similar concept.

To get the documentation, type: rdoc --exclude=tests/ in the root directory of this project.

ThreadPool is very new at this stage and there may still be some obvious errors. Whilst the code is very simple, it is relatively untested aside from several live tests that you can use to see how it works.

You can run all the live tests like this (in linux/unix shell):

$ cd tests/live
$ sh test-all.sh

Some rspec tests are in specs/. Install rspec (gem install rspec) and use the spec command to run them.

Regards, Daniel Bush