Bug #72745 [Opn->Wfx]: reset() work much slower than foreach()

Edit report at https://bugs.php.net/bug.php?id=72745&edit=1 ID: 72745 Updated by: nikic@php.net Reported by: sailormax at inbox dot lv Summary: reset() work much slower than foreach() -Status: Open +Status: Wont fix Type: Bug Package: Arrays related PHP Version: 7.0.9 Block user comment: N Private report: N New Comment: I'm afraid there is not much we can do here. The problem you're running into is that reset($arr2) is forced to actually perform the copy that was delayed in the $arr2 = $arr line. This means you're copying the array on each iteration. The reason is that reset($arr2) actually modifies $arr2 (it modifies the internal array pointer), while as of PHP 7 by-value foreach no longer modifies $arr2 (it uses an external array pointer). If possible, try to avoid using reset(), or alternatively don't copy the array beforehand. Doing reset($arr) (without $arr2 = $arr) should give you non-quadratic performance. Previous Comments: ------------------------------------------------------------------------ [2016-08-03 15:22:41] sailormax at inbox dot lv Description: ------------ reset() work much slower than foreach() under PHP7 Looks like developers optimized foreach(), but forgot about reset(). Under PHP5 speeds are similar. Test script: --------------- $arr = array_fill(0, 10000, "a"); $ts = microtime(true); $first_key = -1; foreach ($arr as $k => $v) { $arr2 = $arr; reset($arr2); $first_key = key($arr2); } echo microtime(true)-$ts, "<br />\n"; echo $first_key, "<br />\n"; $ts = microtime(true); $first_key = -1; foreach ($arr as $k => $v) { $arr2 = $arr; foreach ($arr2 as $k2 => $v2) break; $first_key = $k2; } echo microtime(true)-$ts, "<br />\n"; echo $first_key, "<br />\n"; Expected result: ---------------- 0.0011060237884521 0 0.0011060237884521 0 Actual result: -------------- 0.64054489135742 0 0.0011060237884521 0 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=72745&edit=1