These 2 lines confuse me 

kill 0, $pid while sleep 1 and $timeout--;
kill 3, $pid if $timeout;

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What are you trying to do here? It appears, that you repeat sleep(1) until $timeout is 0. In this case, the second line does nothing, so your thread is not terminated. Probably you wanted to have 
sleep 1 while kill(0, $pid) && $timeout--;
kill 3, $pid if $timeout;

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Could it be, that running thread messes up the array?

In reply to Re: One piece of code, two mysteries! by andal
in thread One piece of code, two mysteries! (UPDATED.) by BrowserUk

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