in reply to Did I create a concurrent program?

Your mytest routine will run concurrently, but you have a race condition. You should pass the value of $j into the thread at thread creation time instead of accessing a global variable. As your threads run, there is a chance that two threads will try to use the same value in $j to move a file. Also, there is little sense in using threads for IO operations, as IO operations that use the full bandwidth of the bus available seldom benefit from parallelization.

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Re^2: Did I create a concurrent program?
by JavaFan (Canon) on Nov 19, 2008 at 14:05 UTC
    Your mytest routine will run concurrently, but you have a race condition. You should pass the value of $j into the thread at thread creation time instead of accessing a global variable. As your threads run, there is a chance that two threads will try to use the same value in $j to move a file.
    Aren't Perl variables supposed to be non-shared by default?
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Re^2: Did I create a concurrent program?
by jweden1 (Initiate) on Nov 19, 2008 at 22:30 UTC
    Thanks, I didn't consider that. Thanks for all the advice everyone. I had a problem doing something like this: 
    threads->create(\&mytest($j));

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    ...and then reading in $j via @_ in the subroutine. This may have something to do with passing by reference via \&? Sorry, I forget what the error was but it wasn't allowed. Any ideas why?
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