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manumilou/array-is-not-thread-safe.rb

Created March 19, 2019 22:29
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Appending to arrays is not thread-safe in Ruby.
Raw
array-is-not-thread-safe.rb
array = []
5.times.map do
Thread.new do
1000.times do
array << nil
end
end
end.each(&:join)
puts array.size
@manumilou
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Making this code atomic to ensure that it can't be interrupted until it's finished. The simplest way to make an operation like this atomic is to use a lock.

array = []
mutex = Mutex.new

5.times.map do
  Thread.new do

    mutex.synchronize do
      1000.times do
        array << nil
      end
    end

  end
end.each(&:join)

puts array.size

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