On Mon, Mar 18, 2013 at 10:12 AM, Ken Paul <[email protected]> wrote: > Is there a way to know how many child processes that have been forked by > its parent process?
Yes, just record the PID in a Set or Array. > The forked process may exit when it finishes, so if > parent process needs to know the status, it has to check it regularly. That's not how you typically do it. Typically you will fork child processes and then wait for them to terminate once you are doing with your work in the main process. If you want to limit the total number of processes created you could store work items in a queue, start n processes initially and then wait for one process to terminate. As long as there is work in the queue fork a new process. > I'm guess this number could be used to control the total numbers > processes to avert too many resources exhausted. Once the number is > reduced, new child could be forked. You just need to wait for termination (see above). http://www.ruby-doc.org/core-1.9.3/Process.html Example: #!/usr/bin/ruby $-w = true require 'set' N = 4 # work items are sleep seconds queue = 20.times.map { 2 + rand(5) } processes = Set.new until queue.empty? if processes.size >= N pid = Process.wait processes.delete pid end sl = queue.shift pid = fork do printf "PID %5d: Start\n", $$ sleep sl printf "PID %5d: Stop\n", $$ end processes.add pid end puts "Waiting for remaining processes..." Process.waitall puts "Done" -- remember.guy do |as, often| as.you_can - without end http://blog.rubybestpractices.com/ -- [email protected] | https://groups.google.com/d/forum/ruby-talk-google?hl=en --- You received this message because you are subscribed to the Google Groups "ruby-talk-google" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
