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
