class SimpleThreadPool
Simple thread pool for executing blocks in parallel in a controlled manner. Threads are not re-used by the pool to prevent any thread local variables from leaking out.
Public Class Methods
# File lib/simple_thread_pool.rb, line 11 def initialize(max_threads) @max_threads = max_threads @lock = Mutex.new @threads = [] @processing_ids = [] end
Public Instance Methods
Call this method to spawn a thread to run the block. If the thread pool is already full, this method will block until a thread is free. The block is responsible for handling any exceptions that could be raised.
The optional id argument can be used to provide an identifier for a block. If one is provided, processing will be blocked if the same id is already being processed. This ensures that each unique id is executed one at a time sequentially.
# File lib/simple_thread_pool.rb, line 26 def execute(id = nil, &block) loop do # Check if a new thread can be added without blocking. while !can_add_thread?(id) sleep(0.001) end @lock.synchronize do # Check again inside a synchronized block if the thread can still be added. if can_add_thread?(id) @processing_ids << id unless id.nil? add_thread(id, block) return end end end end
Call this method to block until all current threads have finished executing.
# File lib/simple_thread_pool.rb, line 45 def finish active_threads = @lock.synchronize { @threads.select(&:alive?) } active_threads.each(&:join) nil end
Synchronize data access across the thread pool. This method will block waiting on the same internal Mutex the thread pool uses to manage scheduling threads.
# File lib/simple_thread_pool.rb, line 54 def synchronize(&block) @lock.synchronize(&block) end
Private Instance Methods
Spawn a thread in this method to ensure that it doesn't accidentally pick up any local variables.
# File lib/simple_thread_pool.rb, line 65 def add_thread(id, block) main_thread = Thread.current @threads << Thread.new do begin block.call # Return nil to ensure no objects are leaked. nil ensure @lock.synchronize do @processing_ids.delete(id) unless id.nil? @threads.delete(Thread.current) end main_thread.wakeup if main_thread.alive? end end nil end
# File lib/simple_thread_pool.rb, line 60 def can_add_thread?(id) @threads.size < @max_threads && (id.nil? || !@processing_ids.include?(id)) end