Steals INT if ran in a thread that dies prematurely

[ripienaar]

I have a complex case where I want to use systemu to run programs but the thread that happens in might sometimes die.

here's a simple bit of code that demonstrates:

Signal.trap("INT") do
    puts "Int!"
end

Process.kill(2, $$)

s = Thread.new {
    systemu("sleep 10") do |pid|
        Process.waitpid(pid)
    end
}

sleep 4

s.terminate
puts "terminated thread..."

sleep 10

3.times {
    Process.kill(2, $$)
    puts "self killed..."
    sleep 0.5
}

Process.kill(9, $$)

If you run this you'll see the first Int gets received, it then starts a thread that sleeps for 10 seconds - but 4 seconds into the 10 the thread gets killed.

The sleep continues till its past its 10 seconds - thats great and what I want - but after that the INT signal is ignored.

The calling thread wont exit often but its possible something can go wrong and so loosing INT is a problem. In cases where the thread doesn't exit then INT is still fine

[ahoward]

you probably want to use this idiom to organize your pids before you starting handling signals

q = Queue.new

Thread.new{ systemu('sleep 10'){|pid| q.push(pid)} }

pid = q.pop

causing an entire process to wait from inside a thread is meaningless in ruby: everything stops there