From: scope at planetavent dot de Operating system: Windows Server 2008 / RHEL 6.3 PHP version: 5.4.10 Package: Strings related Bug Type: Bug Bug description:poor efficiency of strtr() using array with keys of very different length
Description: ------------ As the documentation of strtr() points out, strtr "... will be the most efficient when all the keys have the same size". Using keys of very different lengths results in poor performance, even on very small inputs. If the str_repeat() for "m" in the test script is adjusted to 20000 the resulting runtime increases to 45 seconds for strtr() while str_replace() does not increase notably. There are cases where the replacement array is built dynamically, so there might be little control over the keylengths. It's easy to expand the example such that strtr() takes several hours compared to just a few seconds using str_replace(). Test script: --------------- <?php $text = str_repeat( 'm', 2000 ); $long_from_a = str_repeat( 'a', 1 ); $long_from_x = str_repeat( 'x', 1500 ); $replacements = array( $long_from_a => 'b', $long_from_x => 'y' ); $start = microtime( true ); $result_1 = strtr( $text, $replacements ); echo "strtr: " . number_format( microtime( true ) - $start, 4 ) . "\n"; $start = microtime( true ); $result_2 = str_replace( array_keys( $replacements ), array_values( $replacements ), $text ); echo "str_replace: " . number_format( microtime( true ) - $start, 4 ) . "\n"; echo $result_1 === $result_2 ? "results match!\n": "no match!\n"; Expected result: ---------------- strtr: 0.0001 str_replace: 0.0001 results match! Actual result: -------------- strtr: 2.4203 str_replace: 0.0001 results match! -- Edit bug report at https://bugs.php.net/bug.php?id=63893&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=63893&r=trysnapshot54 Try a snapshot (PHP 5.3): https://bugs.php.net/fix.php?id=63893&r=trysnapshot53 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=63893&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=63893&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=63893&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=63893&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=63893&r=needscript Try newer version: https://bugs.php.net/fix.php?id=63893&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=63893&r=support Expected behavior: https://bugs.php.net/fix.php?id=63893&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=63893&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=63893&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=63893&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=63893&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=63893&r=dst IIS Stability: https://bugs.php.net/fix.php?id=63893&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=63893&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=63893&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=63893&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=63893&r=mysqlcfg
