问题描述

如果 real_usage 参数设置为 true，PHP DOCS 会说它将获得系统分配的实际内存大小.如果它是 false 它将获得 emalloc()

If the real_usage argument is set to true the PHP DOCS say it will get the real size of memory allocated from system. If it's false it will get the memory reported by emalloc()

这两个选项中的哪一个返回最大值.相对于php.ini中的内存限制值分配的内存?

Which one of these 2 options returns the max. memory allocated relative to the memory limit value in php.ini ?

我想知道脚本离达到该限制有多近.

I want to know how close was the script to hit that limit.

推荐答案

好的，让我们用一个简单的脚本来测试一下:

Ok, lets test this using a simple script:

ini_set('memory_limit', '1M');
$x = '';
while(true) {
  echo "not real: ".(memory_get_peak_usage(false)/1024/1024)." MiB
";
  echo "real: ".(memory_get_peak_usage(true)/1024/1024)." MiB

";
  $x .= str_repeat(' ', 1024*25); //store 25kb more to string
}

输出:

not real: 0.73469543457031 MiB
real: 0.75 MiB

not real: 0.75910949707031 MiB
real: 1 MiB

...

not real: 0.95442199707031 MiB
real: 1 MiB

not real: 0.97883605957031 MiB
real: 1 MiB

PHP Fatal error:  Allowed memory size of 1048576 bytes exhausted (tried to allocate 793601 bytes) in /home/niko/test.php on line 7

似乎真正的使用是从系统分配的内存 - 这似乎是在比脚本当前所需的更大的存储桶中分配的.(我猜是出于性能原因).这也是php进程使用的内存.

Seems like real usage is the memory allocated from the system - which seems to get allocated in larger buckets than currently needed by the script. (I guess for performance reasons). This is also the memory the php process uses.

$real_usage = false 使用量是您在脚本中实际使用的内存使用量，而不是 Zend 的内存管理器分配的实际内存量.

The $real_usage = false usage is the memory usage you actually used in your script, not the actual amount of memory allocated by Zend's memory manager.

阅读这个问题了解更多信息.

简而言之:要了解您离内存限制有多近，请使用 $real_usage = true

In short: to get how close are you to the memory limit, use $real_usage = true

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