ID: 25007 Updated by: [EMAIL PROTECTED] Reported By: dcowgill at mail dot communityconnect dot com -Status: Assigned +Status: Closed Bug Type: Performance problem Operating System: Linux PHP Version: 4.3.3RC3 Assigned To: iliaa New Comment:
This bug has been fixed in CVS. In case this was a PHP problem, snapshots of the sources are packaged every three hours; this change will be in the next snapshot. You can grab the snapshot at http://snaps.php.net/. In case this was a documentation problem, the fix will show up soon at http://www.php.net/manual/. In case this was a PHP.net website problem, the change will show up on the PHP.net site and on the mirror sites in short time. Thank you for the report, and for helping us make PHP better. Previous Comments: ------------------------------------------------------------------------ [2003-08-10 18:20:07] dcowgill at mail dot communityconnect dot com Description: ------------ >From the docs for rand: "In older versions of PHP, you had to seed the random number generator before use with srand(). Since 4.2.0 this is no longer necessary." The implication is that rand seeds the RNG the first time it is called, unless srand has been previously called; however, rand seeds the RNG every time (or until srand is explicitly called). This results in a significant increase in running time (about an order of magnitude). The above also applies to mt_rand, except that the performance penalty is greater (apparently because its seed-generation algorithm is more expensive). (the patch to ext/standard/rand.c to correct the problem is trivial) Reproduce code: --------------- // t1.php <? for ($i=0; $i<100000; $i++) rand(0,10); ?> // t2.php <? srand(); for ($i=0; $i<100000; $i++) rand(0,10); ?> Actual result: -------------- $ time php t1.php real 0m0.729s user 0m0.650s sys 0m0.080s $ time php t2.php real 0m0.101s user 0m0.100s sys 0m0.000s ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=25007&edit=1
