{"id":745,"date":"2014-09-28T18:57:48","date_gmt":"2014-09-28T18:57:48","guid":{"rendered":"http:\/\/www.nikola-breznjak.com\/blog\/?p=745"},"modified":"2015-08-17T06:15:57","modified_gmt":"2015-08-17T06:15:57","slug":"php-memory_get_peak_usage-and-ini_setmemory_limit-1","status":"publish","type":"post","link":"https:\/\/nikola-breznjak.com\/blog\/stack-overflow\/php-memory_get_peak_usage-and-ini_setmemory_limit-1\/","title":{"rendered":"PHP memory_get_peak_usage and ini_set(‘memory_limit’, ‘-1’)"},"content":{"rendered":"

\"profile<\/a>
\nI’m a big fan of Stack Overflow<\/a> and I tend to contribute regularly (am currently in the top 0.X%<\/a>).\u00a0In this category (stackoverflow<\/a>)\u00a0of posts I will will be posting my top rated questions and answers. This, btw, is allowed as explained in the meta thread here<\/a>.<\/p>\n

My quesiton<\/a> was:<\/p>\n

I recently ran into memory allocation problems, so I started experimenting with the\u00a0ini_set('memory_limit', value);<\/code>\u00a0directive where I tried to enter values incrementaly. Now, searching through the web (and SO) I found out that I can put\u00a0-1<\/code>\u00a0as the\u00a0value<\/code>. So, I did and now the script runs fully to the end without breaking (before I used to get the memory allocation error).<\/p>\n

What I don’t understand, however, is that given these two lines at the end of the script’s file:<\/p>\n

$mem <\/span>=<\/span> memory_get_peak_usage<\/span>(<\/span>true<\/span>);<\/span>         \r\necho <\/span>\"Peak mem. usage: <b>\"<\/span>.<\/span> round<\/span>(<\/span>$mem <\/span>\/<\/span>1024<\/span>\/<\/span>10124<\/span>,<\/span>2<\/span>)<\/span>.<\/span>\"<\/b> MB\"<\/span>;<\/span><\/code><\/pre>\n
produce around\u00a010.8MB<\/strong>\u00a0and when I look into the\u00a0\/var\/log\/messages<\/code>\u00a0I can see this line:<\/p>\n
Nov<\/span>21<\/span>13<\/span>:<\/span>52<\/span>:<\/span>26<\/span> mail suhosin<\/span>[<\/span>1153<\/span>]:<\/span> ALERT<\/span>-<\/span>SIMULATION <\/span>-<\/span> script tried to increase  \r\nmemory_limit to <\/span>4294967295<\/span> bytes which <\/span>is<\/span> above the allowed value <\/span>(<\/span>attacker  \r\n<\/span>'xx.xxx.xxx.xxx'<\/span>,<\/span> file <\/span>'\/var\/www\/html\/file.php'<\/span>,<\/span> line <\/span>5<\/span>)<\/span><\/code><\/pre>\n
which means the script tried to alocate\u00a04096MB<\/strong>!<\/p>\n
How can this be? And also, what interest me the most is why didn’t the script execution stop in this case? Is it because of the\u00a0ini_set('memory_limit', '-1');<\/code>? I mean, I did read that putting\u00a0-1<\/code>\u00a0as the\u00a0value<\/code>is not recomended and I know where the problem lies in the script (reading too big amount of data at once in the memory), and I will go and fix it with sequential reading, but I’m just baffled about these data differences, so I would be gratefull if someone can shed some light on it.<\/p>\n
It is because the suhosin patch uses its own “hard” maximum memory limit,\u00a0suhosin.memory_limit<\/code><\/a>.<\/p>\n
From the configuration reference:<\/p>\n
Suhosin […] disallows setting the\u00a0memory_limit<\/code>\u00a0to a value\u00a0greater than the one the script started with<\/strong>, when this option is left at 0.<\/p><\/blockquote>\n
In other words, if you change the\u00a0memory_limit<\/code>\u00a0so that it is bigger than suhosin’s upper limit then it will simply assume that you are an “attacker” trying to do something suspicious<\/p><\/blockquote>\n","protected":false},"excerpt":{"rendered":"
I’m a big fan of Stack Overflow and I tend to contribute regularly (am currently in the top 0.X%).\u00a0In this category (stackoverflow)\u00a0of posts I will will be posting…<\/p>\n","protected":false},"author":1,"featured_media":609,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[35],"tags":[],"class_list":["post-745","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-stack-overflow"],"_links":{"self":[{"href":"https:\/\/nikola-breznjak.com\/blog\/wp-json\/wp\/v2\/posts\/745","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/nikola-breznjak.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/nikola-breznjak.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/nikola-breznjak.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/nikola-breznjak.com\/blog\/wp-json\/wp\/v2\/comments?post=745"}],"version-history":[{"count":2,"href":"https:\/\/nikola-breznjak.com\/blog\/wp-json\/wp\/v2\/posts\/745\/revisions"}],"predecessor-version":[{"id":1710,"href":"https:\/\/nikola-breznjak.com\/blog\/wp-json\/wp\/v2\/posts\/745\/revisions\/1710"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/nikola-breznjak.com\/blog\/wp-json\/wp\/v2\/media\/609"}],"wp:attachment":[{"href":"https:\/\/nikola-breznjak.com\/blog\/wp-json\/wp\/v2\/media?parent=745"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nikola-breznjak.com\/blog\/wp-json\/wp\/v2\/categories?post=745"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nikola-breznjak.com\/blog\/wp-json\/wp\/v2\/tags?post=745"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
The answer, by user\u00a0Sverri M. Olsen<\/a>\u00a0was:<\/p>\n