The error occurs because you are calling tempdir before your loop. This makes File::Temp call srand internally, and all subsequent forks inherit the seeded random value.

Thanks for this! I did not know this is how things work, didn't bother looking through the source for more than a few minutes.

FWIW, I call tempdir first because I want all the forks to dump their files into the same dir so I can collect their output easily in the parent when they finish. (I would think this would be a common pattern, but maybe not.)

This is why I included slightly more source than you personally would prefer -- I wanted to show a bit of why I am doing this the way I am doing it. It is reduced considerably from the actual code (down to 26 lines not counting __DATA__ vs. 13 lines for yours). On further consideration, I would probably cut it down as you suggest, and deal with any "why did you do this" questions as they come up (instead of preempting them).

In any case, I doubt I would have stumbled on anything involving srand no matter how much I cut down my code, as it was never in my code! I only know about it because you pointed it out to me, so thanks.

RT

In reply to Re^2: File::Temp randomness when forking by ryantate
in thread File::Temp randomness when forking by ryantate

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