[PHP]Fatal error: Allowed memory size of x bytes exhausted (tried to allocate y bytes)

A user complained to me that my PHP web applications stopped working today. After I digged into the error log, I found that following message:

PHP Fatal error:  Allowed memory size of 262144 bytes exhausted (tried to allocate 261900 bytes) in Unknown on line 0

Obviously, this is related to the memory error. Therefore I tried to increase the limit of memory_limit in php.ini. Since I have 8G of memory in my box, I think it is okay to set the memory limit of PHP to 4GB.

;memory_limit = 128M
memory_limit = 4096M

When I restart the Apache/PHP, I found another nightmare. My web application stopped working! When the user tries to access http://mywebsite/index.php, instead of rendering the code, the browser kept prompting the user to download the file.

After scratching my head for a while, I found that I missed something, which is very very important. I was running XAMPP (32-bit) on a Fedora 64-bit machine. See the problem? Since XAMPP is running in 32-bit, it does not understand what is 4096 MB. (If you install 4GB of memory in any Windows 32-bit machine, you will notice that Windows can only allocate 3GB of them, and the 1GB left memory is sitting inside your computer and doing nothing…) Therefore, I decrease the memory_limit to 2048MB, and that solved the problem.

Time to move away from XAMPP.


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One Reply to “[PHP]Fatal error: Allowed memory size of x bytes exhausted (tried to allocate y bytes)”

  1. Daniel

    Thank you so much. I was sitting on PC the last 4hours and didn’t think of the 32bit limitation…
    I was hitting the same problem in PHP running on IIS.


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