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Bug #6634 » thread_deadlock_error_test.rb

Test code to show how this error occurs - we4tech (nhm tanveeer hossain khan), 04/30/2013 12:12 AM

 
require 'minitest/autorun'

class ThreadPool
attr_accessor :size, :threads, :jobs

def initialize(size)
@size = size
@jobs = Queue.new
@threads = create_threads
end

def create_threads
@size.times.map do |i|
Thread.start do
Thread.current[:id] = i

catch(:thread_quit) do
loop do
job, args = @jobs.pop
job.call *args
end
end
end
end
end

def join
threads.each &:join
end

def shutdown
size.times do
add { throw :thread_quit }
end

threads.map &:join
end

def add(*args, &job)
jobs << [job, args]
end

def queue_size;
jobs.size
end
end

describe ThreadPool do
before do
@pool = ThreadPool.new 2
@pool.extend MiniTest::Expectations
end

it 'generates "No live threads left. Deadlock?deadlock?"' do
100.times do |i|
@pool.add(i) do |i|
puts "doing (#{i + 1})..."
sleep 0.01
end
end

begin
@pool.join
rescue Exception => e
assert_equal 'No live threads left. Deadlock?', e.message
end
end

it 'works with workaround' do
100.times do |i|
@pool.add(i) do |i|
puts "doing (#{i + 1})..."
sleep 0.01
end
end

exception = nil

begin
Thread.start do
break until @pool.threads.select(&:alive?).size.zero?
end.join
sleep 1
rescue Exception => e
exception = e
end

assert_nil exception
end
end
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