From:
Operating system: OS X 10.6.8
PHP version: 5.3.6
Package: Performance problem
Bug Type: Bug
Bug description:strpos() performs poorly when given start index
Description:
------------
When strpos() is given an index position to start searching, it actually
performs
more poorly than when the parameter is left off (thus defaulting to "0").
One
would expect that giving it a starting index would improve performance
since it
could skip checking so many characters.
I've been able to reproduce this issue consistently with the attached
script.
Two loops, each run 1 million times. The first loop specifies a start index
of 2,
whereas the second one doesn't specify one. You would expect the first loop
to run
faster. Try reversing this (giving the second loop a start index) and you
will see
the execution time results flip, as well.
My framework makes heavy use of strpos() and I discovered this issue when I
attempted to optimize strpos() by skipping the first few characters of the
string
to be checked. No go.
Test script:
---------------
<?php
$k = 'image:0:{name}.{ext}';
$start = microtime(TRUE);
for ($i = 0; $i < 1000000; $i++) {
strpos($k, '{', 2);
}
echo "<p>Seconds: ".(microtime(TRUE) - $start).'</p>';
$start = microtime(TRUE);
for ($i = 0; $i < 1000000; $i++) {
strpos($k, '{');
}
echo "<p>Seconds: ".(microtime(TRUE) - $start).'</p>';
Expected result:
----------------
Specifying a start index would result in better performance since it has
less to
check.
Actual result:
--------------
Specifying a start index actually has a negative impact on the performance
of the
script, possibly due to logic where it must check if the index is positive
or
negative.
--
Edit bug report at https://bugs.php.net/bug.php?id=55254&edit=1
--
Try a snapshot (PHP 5.4):
https://bugs.php.net/fix.php?id=55254&r=trysnapshot54
Try a snapshot (PHP 5.3):
https://bugs.php.net/fix.php?id=55254&r=trysnapshot53
Try a snapshot (trunk):
https://bugs.php.net/fix.php?id=55254&r=trysnapshottrunk
Fixed in SVN:
https://bugs.php.net/fix.php?id=55254&r=fixed
Fixed in SVN and need be documented:
https://bugs.php.net/fix.php?id=55254&r=needdocs
Fixed in release:
https://bugs.php.net/fix.php?id=55254&r=alreadyfixed
Need backtrace:
https://bugs.php.net/fix.php?id=55254&r=needtrace
Need Reproduce Script:
https://bugs.php.net/fix.php?id=55254&r=needscript
Try newer version:
https://bugs.php.net/fix.php?id=55254&r=oldversion
Not developer issue:
https://bugs.php.net/fix.php?id=55254&r=support
Expected behavior:
https://bugs.php.net/fix.php?id=55254&r=notwrong
Not enough info:
https://bugs.php.net/fix.php?id=55254&r=notenoughinfo
Submitted twice:
https://bugs.php.net/fix.php?id=55254&r=submittedtwice
register_globals:
https://bugs.php.net/fix.php?id=55254&r=globals
PHP 4 support discontinued:
https://bugs.php.net/fix.php?id=55254&r=php4
Daylight Savings: https://bugs.php.net/fix.php?id=55254&r=dst
IIS Stability:
https://bugs.php.net/fix.php?id=55254&r=isapi
Install GNU Sed:
https://bugs.php.net/fix.php?id=55254&r=gnused
Floating point limitations:
https://bugs.php.net/fix.php?id=55254&r=float
No Zend Extensions:
https://bugs.php.net/fix.php?id=55254&r=nozend
MySQL Configuration Error:
https://bugs.php.net/fix.php?id=55254&r=mysqlcfg
