Bug #71153 [NEW]: Performance Degradation in ArrayIterator with large arrays

From: kontakt at beberlei dot de Operating system: Linux/Ubuntu 15.04 PHP version: 7.0.1 Package: *General Issues Bug Type: Bug Bug description:Performance Degradation in ArrayIterator with large arrays Description: ------------ When creating array iterators with large array, iterating over them will be *much* slower than just iterating over the array itself. The larger the array gets the exponentially slower the iteration gets. Memory usage increases as well. For the same script PHP 5 doesn't have the problem, it is pretty fast on any size of array iterator. This problem was found in Twig, see my explanation comment: https://github.com/twigphp/Twig/issues/1810 Test script: --------------- <?php class Node implements IteratorAggregate { private $nodes; public function __construct(array $nodes) { $this->nodes = $nodes; } public function getIterator() { return new ArrayIterator($this->nodes); } public function getNodes() { return $this->nodes; } public function visitIterator() { foreach ($this as $node) { $node->visitIterator(); } } public function visitNodes() { foreach ($this->getNodes() as $node) { $node->visitNodes(); } } } gc_disable(); $sizes = [1000, 10000, 20000, 65000, 66000, 100000]; foreach ($sizes as $size) { echo "Array Size $size\n"; $nodes = []; for ($i = 0; $i < $size; $i++) { $nodes[] = new Node([]); } $node = new Node($nodes); $time = microtime(true); $node->visitNodes(); echo "Array: " . number_format(microtime(true) - $time , 4) . " " . memory_get_peak_usage() . "\n"; $time = microtime(true); $node->visitIterator(); echo "Iterator: " . number_format(microtime(true) - $time , 4) . " " . memory_get_peak_usage() . "\n"; echo "\n"; } Expected result: ---------------- PHP 7 being faster than PHP 5 on every size of ArrayIterator, not just with size 1000. Actual result: -------------- Array Size 1000 Array: 0.0001 695232 Iterator: 0.0009 730208 Array Size 10000 Array: 0.0019 2464128 Iterator: 0.0607 3003872 Array Size 20000 Array: 0.0027 5898752 Iterator: 0.5189 5898752 Array Size 65000 Array: 0.0130 14741656 Iterator: 5.0322 14741656 Array Size 66000 Array: 0.0107 24079792 Iterator: 12.1315 24079792 Array Size 100000 Array: 0.0141 32198240 Iterator: 34.8082 32198240 -- Edit bug report at https://bugs.php.net/bug.php?id=71153&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=71153&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=71153&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=71153&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=71153&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=71153&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=71153&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=71153&r=needscript Try newer version: https://bugs.php.net/fix.php?id=71153&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=71153&r=support Expected behavior: https://bugs.php.net/fix.php?id=71153&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=71153&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=71153&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=71153&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=71153&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=71153&r=dst IIS Stability: https://bugs.php.net/fix.php?id=71153&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=71153&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=71153&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=71153&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=71153&r=mysqlcfg