JezK
Edit File: thread_pool.rb
require 'thread' require 'set' require 'rake/promise' module Rake class ThreadPool # :nodoc: all # Creates a ThreadPool object. # The parameter is the size of the pool. def initialize(thread_count) @max_active_threads = [thread_count, 0].max @threads = Set.new @threads_mon = Monitor.new @queue = Queue.new @join_cond = @threads_mon.new_cond @history_start_time = nil @history = [] @history_mon = Monitor.new @total_threads_in_play = 0 end # Creates a future executed by the +ThreadPool+. # # The args are passed to the block when executing (similarly to # <tt>Thread#new</tt>) The return value is an object representing # a future which has been created and added to the queue in the # pool. Sending <tt>#value</tt> to the object will sleep the # current thread until the future is finished and will return the # result (or raise an exception thrown from the future) def future(*args, &block) promise = Promise.new(args, &block) promise.recorder = lambda { |*stats| stat(*stats) } @queue.enq promise stat :queued, :item_id => promise.object_id start_thread promise end # Waits until the queue of futures is empty and all threads have exited. def join @threads_mon.synchronize do begin stat :joining @join_cond.wait unless @threads.empty? stat :joined rescue Exception => e stat :joined $stderr.puts e $stderr.print "Queue contains #{@queue.size} items. " + "Thread pool contains #{@threads.count} threads\n" $stderr.print "Current Thread #{Thread.current} status = " + "#{Thread.current.status}\n" $stderr.puts e.backtrace.join("\n") @threads.each do |t| $stderr.print "Thread #{t} status = #{t.status}\n" # 1.8 doesn't support Thread#backtrace $stderr.puts t.backtrace.join("\n") if t.respond_to? :backtrace end raise e end end end # Enable the gathering of history events. def gather_history #:nodoc: @history_start_time = Time.now if @history_start_time.nil? end # Return a array of history events for the thread pool. # # History gathering must be enabled to be able to see the events # (see #gather_history). Best to call this when the job is # complete (i.e. after ThreadPool#join is called). def history # :nodoc: @history_mon.synchronize { @history.dup }. sort_by { |i| i[:time] }. each { |i| i[:time] -= @history_start_time } end # Return a hash of always collected statistics for the thread pool. def statistics # :nodoc: { :total_threads_in_play => @total_threads_in_play, :max_active_threads => @max_active_threads, } end private # processes one item on the queue. Returns true if there was an # item to process, false if there was no item def process_queue_item #:nodoc: return false if @queue.empty? # Even though we just asked if the queue was empty, it # still could have had an item which by this statement # is now gone. For this reason we pass true to Queue#deq # because we will sleep indefinitely if it is empty. promise = @queue.deq(true) stat :dequeued, :item_id => promise.object_id promise.work return true rescue ThreadError # this means the queue is empty false end def start_thread # :nodoc: @threads_mon.synchronize do next unless @threads.count < @max_active_threads t = Thread.new do begin while @threads.count <= @max_active_threads break unless process_queue_item end ensure @threads_mon.synchronize do @threads.delete Thread.current stat :ended, :thread_count => @threads.count @join_cond.broadcast if @threads.empty? end end end @threads << t stat( :spawned, :new_thread => t.object_id, :thread_count => @threads.count) @total_threads_in_play = @threads.count if @threads.count > @total_threads_in_play end end def stat(event, data=nil) # :nodoc: return if @history_start_time.nil? info = { :event => event, :data => data, :time => Time.now, :thread => Thread.current.object_id, } @history_mon.synchronize { @history << info } end # for testing only def __queue__ # :nodoc: @queue end def __threads__ # :nodoc: @threads.dup end end end