#42465 [NEW]: rand() and mt_rand() return same values from forked processes

From: bugs at nazarenko dot net Operating system: Linux, Solaris PHP version: 5CVS-2007-08-28 (snap) PHP Bug Type: Math related Bug description: rand() and mt_rand() return same values from forked processes Description: ------------ Using CLI, if more than 1 process is forked with pcntl_fork() both functions mt_rand() and rand() return same values in all child processes. This only happens when there was a call to mt_rand()/rand() in the parent process before forking. Reproduce code: --------------- Compiled latest available snapshot under Solaris 10 and SuSE Linux 10.1 with the following configure options: --disable-all --disable-cgi --enable-pcntl --disable-ipv6 The test script is the following: <?php echo mt_rand(0,255)."\n"; # comment this line out to see difference for ($i=0; $i<3; $i++) { if (pcntl_fork() == 0) { die(mt_rand(0,255)."\n"); } } ?> Expected result: ---------------- Expected result is 4 random numbers generated by 4 different Unix processes (1 parent and 3 children). Actual result: -------------- The actual result (both on Solaris and Linux) is that all 3 numbers generated by the children are the same. Now comment out the first echo command belonging to the parent process and the result is 3 random numbers generated by children. -- Edit bug report at http://bugs.php.net/?id=42465&edit=1 -- Try a CVS snapshot (PHP 4.4): http://bugs.php.net/fix.php?id=42465&r=trysnapshot44 Try a CVS snapshot (PHP 5.2): http://bugs.php.net/fix.php?id=42465&r=trysnapshot52 Try a CVS snapshot (PHP 6.0): http://bugs.php.net/fix.php?id=42465&r=trysnapshot60 Fixed in CVS: http://bugs.php.net/fix.php?id=42465&r=fixedcvs Fixed in release: http://bugs.php.net/fix.php?id=42465&r=alreadyfixed Need backtrace: http://bugs.php.net/fix.php?id=42465&r=needtrace Need Reproduce Script: http://bugs.php.net/fix.php?id=42465&r=needscript Try newer version: http://bugs.php.net/fix.php?id=42465&r=oldversion Not developer issue: http://bugs.php.net/fix.php?id=42465&r=support Expected behavior: http://bugs.php.net/fix.php?id=42465&r=notwrong Not enough info: http://bugs.php.net/fix.php?id=42465&r=notenoughinfo Submitted twice: http://bugs.php.net/fix.php?id=42465&r=submittedtwice register_globals: http://bugs.php.net/fix.php?id=42465&r=globals PHP 3 support discontinued: http://bugs.php.net/fix.php?id=42465&r=php3 Daylight Savings: http://bugs.php.net/fix.php?id=42465&r=dst IIS Stability: http://bugs.php.net/fix.php?id=42465&r=isapi Install GNU Sed: http://bugs.php.net/fix.php?id=42465&r=gnused Floating point limitations: http://bugs.php.net/fix.php?id=42465&r=float No Zend Extensions: http://bugs.php.net/fix.php?id=42465&r=nozend MySQL Configuration Error: http://bugs.php.net/fix.php?id=42465&r=mysqlcfg