During the 2-minute timeout wait to kill test4.sh, nothing else is happening (not even the run_on_start/finish for test5.sh). I still have 2 forkable processes (of the defined 3) that are not being used

That's completely false!!!

on_start for test5 runs long before test4 finishes. Check the timestamps; your output is out of order. (You probably redirected the output, which caused STDOUT to become block buffered. Use $| = 1; to disable buffering on STDOUT.) 

Thu May 14 16:52:40 2015 Started ==> test4.sh
Thu May 14 16:52:40 2015 Started ==> test5.sh
Thu May 14 16:52:43 CDT 2015 I am running test4.sh
Thu May 14 16:52:43 CDT 2015 I am running test5.sh
[If you were to print out when test5 ends, it would be here]
Thu May 14 16:52:53 CDT 2015 I am running test4.sh
Thu May 14 16:53:03 CDT 2015 I am running test4.sh
Thu May 14 16:53:13 CDT 2015 I am running test4.sh
Thu May 14 16:53:23 CDT 2015 I am running test4.sh
Thu May 14 16:53:33 CDT 2015 I am running test4.sh
Thu May 14 16:53:43 CDT 2015 I am running test4.sh
Thu May 14 16:53:53 CDT 2015 I am running test4.sh
Thu May 14 16:54:03 CDT 2015 I am running test4.sh
Thu May 14 16:54:13 CDT 2015 I am running test4.sh
Thu May 14 16:54:23 CDT 2015 I am running test4.sh
Thu May 14 16:54:33 CDT 2015 I am running test4.sh
Thu May 14 16:54:43 CDT 2015 I am running test4.sh

[download]

When test5 is running, there's only one unused process, and that's because there's nothing for that process to do. Only when test5 finishes do you have two unused processes, and that's because there's nothing for those two processes to do (since you want all processes to end before pausing before running the test suite again).

You are right about on_finish, though. on_finish code is not guaranteed to run immediately when the child ends. It will run when the parent reaps the child, which will happen at some point before wait_all_children returns.

In reply to Re^4: Parallel::ForkManager and wait_all_children by ikegami
in thread Parallel::ForkManager and wait_all_children by rgren925

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