note 117967 added to function.srand

srand and mt_srand are both initialized only once per process ID. You cannot re-seed your rand algorithms after the first "srand", "mt_srand", "rand", "mt_rand", "shuffle", or any other rand-like function. I have been facing an issue where after forking my process, all childs were generating exactly the same rand values. This was due a first "shuffle" call on the parent process, so I could not re-seed the childs. To solve my issue, I simple called "rand" N times, to offset the child rand generators. # Offset the child rand generator by its PID $n = (getmypid() % 100) * (10 * abs(microtime(true) - time())); for ($n; $n > 0; $n--) { rand(0, $n); } Since each pcntl_fork takes a while to be completed, the microtime offers an extra offset, other than one PID increment. This small code will make at the WORST hypothesis 1000 iterations. ---- Server IP: 72.52.91.14 Probable Submitter: 189.14.1.241 ---- Manual Page -- http://php.net/manual/en/function.srand.php Edit -- https://master.php.net/note/edit/117967 Del: integrated -- https://master.php.net/note/delete/117967/integrated Del: useless -- https://master.php.net/note/delete/117967/useless Del: bad code -- https://master.php.net/note/delete/117967/bad+code Del: spam -- https://master.php.net/note/delete/117967/spam Del: non-english -- https://master.php.net/note/delete/117967/non-english Del: in docs -- https://master.php.net/note/delete/117967/in+docs Del: other reasons-- https://master.php.net/note/delete/117967 Reject -- https://master.php.net/note/reject/117967 Search -- https://master.php.net/manage/user-notes.php