From: Stephan Maka <stephan@...>
Date: 2006-04-18T01:55:59+09:00
Subject: IO not closed by GC

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Hello,

I often use constructions like the following:

os = IO.popen('uname -sr').readlines.to_s.strip

I assume that the Garbage Collector throws away the IO instance created
by IO::popen, because it's simply not needed after that line anymore.

What I've experienced is, that it leaves a zombie for each time I use
such an instruction.

---

loop {
  zombies = IO.popen('ps ax|grep defunct|wc -l').readlines.to_s.strip
  puts "Number of zombies: #{zombies}"
}

---

This code produces about 100 defunct processes in about 2 seconds.
Operating system is FreeBSD 6.1-RC.

However, if I close the IO object manually, defunct processes stay
constantly at 2-3.

---

loop {
  io = IO.popen('ps ax|grep defunct|wc -l')
  zombies = io.readlines.to_s.strip
  io.close
  puts "Number of zombies: #{zombies}"
}

---

Is this assumed behaviour or a bug? I guess there's a close(2) or
waitpid(2) missing in the IO code...

Stephan.

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