Bug #65723 [Nab]: Memory limit of string

Edit report at https://bugs.php.net/bug.php?id=65723&edit=1 ID: 65723 User updated by: m dot banaszek at smartmedia dot com dot pl Reported by: m dot banaszek at smartmedia dot com dot pl Summary: Memory limit of string Status: Not a bug Type: Bug Package: Scripting Engine problem Operating System: Windows 8 PHP Version: Irrelevant Block user comment: N Private report: N New Comment: Hello, i'm very sorry there should be line : "$string .= $strb; ". I tested your simplified code on my production machine. For 50 tests script fail always on 480MB I use windows serwer 2008 r2 x64, iis 7, php 5.4.14. When use array for test memory usage grows up to 1,9GB as expected. I found temporary solution "http://www.ntcore.com/4gb_patch.php". after patch, string test use 1,5 GB memory and array over 3GB Previous Comments: ------------------------------------------------------------------------ [2013-09-20 20:58:47] aharvey@php.net There are some issues with your test: in its default "string" mode, memory usage never actually increases. If I change it to "array" mode, it behaves how the manual says it will — 81 iterations succeed ($strb is 10,000,000 bytes in size, and the effective memory limit is 838,860,800 bytes), and then the script errors out with an out of memory error (there are 810,000,000 bytes in the array, plus overhead for the array itself, plus $strb, plus general overhead). Bear in mind that the memory limit applies to the entire runtime, not individual variables. A simpler, clearer test is this: <?php ini_set('memory_limit', '800M'); $buffer = ''; while (true) { $buffer .= str_repeat(' ', 10000000); printf("Length of buffer: %d\nMemory usage: %d\n", strlen($buffer), memory_get_usage()); } ?> In short, this behaves as expected and documented. ------------------------------------------------------------------------ [2013-09-20 11:24:10] m dot banaszek at smartmedia dot com dot pl Description: ------------ The PHP manual now states, that strings are limited to 2GB. However in test script, I specify a memory limit to 800MB. I wrote a PHP application where memory usage is growing over time. Unfortunately the size of a single string variable doesn't exceed memory limit of 300-400MB and my test stops. Testing my script on 5.4.17,18,19 and 5.3.10 of PHP versions, but any of this versions don't supported my memory limit or 2GB memory. Test script: --------------- <?php ini_set('memory_limit', '800M'); $string = '1234567890'; $strb = ''; for ($i = 0; $i < 1000000; $i++) $strb .= $string; $arr = array(); $i = 0; $testType = 'string'; //'array' while (1) { $i++; if ('string' == $testType) { error_log((strlen($string) / 1000000) . ' - ' . (memory_get_usage() / 1000000)); } else { $arr[] = $strb . $i; error_log((strlen($string) / 1000000) . ' - ' . (memory_get_usage() / 1000000)); } error_log((count($arr)) . ' - ' . (memory_get_usage() / 1000000)); } Expected result: ---------------- Memory usage grow to about 800MB. Actual result: -------------- Memory error of 300-400MB. So the memory usage does not continually grow to 800MB. ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=65723&edit=1