If you look at the manual, you'll see that fork either returns the pid (and spawns a child) or undef if the fork was unsuccessful causing the code after the unless to finally execute, i.e. whenever the system is being sufficiently thrashed to get an undef() back from fork. Note also the conditions under which the manual states that zombies will be accumulated. The OP code meets the criteria for a zombie factory of von Neumann proportions. In fact the intended functionality only gets executed whenever there is a spawn error and sufficient spawn errors are generated to cause "unless" to function precisely because this code is thrashing the machine enough to cause such errors in turn enough to cause the branches with execs to be executed approximately in parallel, because the spawn error cirmsumstances will occur simultaneously of course. Furthermore, the OPs actual symptoms are explained by this analysis but conflict with yours.

-M

Free your mind

In reply to Re^3: Waiting for an External Program to Finish Executing by Moron
in thread Waiting for an External Program to Finish Executing by awohld

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