Here's the POD for my new Parallel::Simple module:
NAME Parallel::Simple - the simplest way to run code blocks in parallel
SEE ALSO Parallel::ForkControl, Parallel::ForkManager, and Parallel::Jobs are all similarly themed, and offer different interfaces and advanced fea- tures. I suggest you skim the docs on all three (in addition to mine) before choosing the right one for you. Or you can foolishly trust the executive summaries below:
Parallel::ForkControl
Only takes one subroutine reference to run, but provides wonderful ways to control how many children are forked and keeping activity below certain thresholds. Arguments to the run() method will be passed on to the subroutine you specified during construction, so there's some run-time flexibility. It is not yet possible to learn anything about what happened to the forked children, such as inspecting return or exit values.
Conclusion: Best for repetitive, looped tasks, such as fetching web pages or running a command across a cluster of machines in paral- lel.
Incidentally, Parallel::ForkControl would be far more useful with the following two changes:
o Support some kind of feedback - return/exit values at a mini- mum, or even a single value summary, like the return value of my prun method.
o Allow the user to specify the Code value in the run method instead of during construction. Then Parallel::ForkControl could do everything this module does and more, albeit with a more sophisticated interface.
Parallel::ForkManager
Unique in the Parallel::* world in that it keeps the user somewhat involved in the forking process. Rather than taking a code refer- ence, you call the start() method to fork and test the return value to determine whether you are now the parent or child... almost like just calling fork yourself. :)
Provides control over how many child processes to allow, and blocks new forks until some previous children have exited. Let's child determine the process exit value. Provides a trigger mechanism to run callbacks when certain events happen (child start, child exit, and start blocking). You must supply a callback for the child exit event to inspect the exit value of the child.
Conclusion: While also designed for repetitive, looped tasks, it is far more flexible, being a thin wrapper around fork rather than taking over child creation and management entirely. Useful mostly if you want to limit child processes to a certain number at a time and/or if the native system calls scare you.
Parallel::Jobs
Different in that it executes shell commands as opposed to subrou- tines or code blocks. Provides all the features of the open3 func- tion, including explicit control over STDIN, STDOUT, and STDERR on all 'jobs'. Lets you monitor jobs for output and exit events (with associated details for each event).
Conclusion: Great for shell commands! Not great for not shell com- mands.
This is a phenomenal initial cut of a POD. The review of relevant other modules in SEE ALSO and the philisophical differences with each deserves particular note. Bravo.
-- </chris>
"There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author)
