After rummaging around in File::Temp's guts and inserting some print statements for debugging, it seems that each of children try to use the same strings for the temporary filename(s).

Under the covers, the random number generator is used to produce a random set of characters to replace the "XXXX" that you can pass in the filename template. But if you're forking, each child is going to inherit the same starting seed, possibly leading to each child generating the same "random" name. Oops.

One way around this might be to reseed the random number generator for each child after you fork (using srand(), and passing it the child's process id).

Another way might be to use the optional "SUFFIX" argument and stick the process id in the suffix. Try something like 

  ($fh, $filename) = tempfile($template, SUFFIX => ".$$")

[download]
and see if it works for you. Using the PID as a suffix a fairly standard convention.

In reply to Re: Poor randomness with File::Temp and fork(). by dws
in thread Poor randomness with File::Temp and fork(). by BazB

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