Upper memory limit for PHP/Apache

Question

I'm getting the error when I run my PHP script....

Fatal error: Out of memory (allocated 1827405824) (tried to allocate 88800 bytes)

I've added this line to my PHP script..

ini_set("memory_limit","3000M");

This statement does seem to correctly control the memory usage, but I dont seem to be able to get it above about 1.8GB. Its as if the upper memory limit is being restricted somewhere else. I've also added to the php.ini...

memory_limit = 3000M

Does anyone know if the memory is restricted elsewhere?

I'm running a local server with Xampp. I have Windows 7, 64-bit with 4GB RAM. My script uses PHP's GD image library and I get the error when trying to allocate an image reference with ImageCreateTrueColor().

(I know this is a huge amount of memory - but this is just a one-of script, and its just a lot easier to do it this way.)

Thanks.

Update....

@elusive @Orbling I expect everybody's bored whith this question, but here is the simplified code which illustrates the problem.

<?php
    ini_set("memory_limit","4000000000");
    echo "ini_get = " . ini_get('memory_limit') . "<br>\n";
    echo "memory_get_usage = " . memory_get_usage(true) . "<br>\n";
    $bigImageHandle = imagecreatetruecolor(22200, 24800);  //this is line 5
?>

Browser output...

ini_get = 4000000000
memory_get_usage = 524288

Fatal error: Out of memory (allocated 1843396608) (tried to allocate 88800 bytes) in
E:\User\My_Webs\experiments\houseshunting\temp\osMaps\t1.php on line 5

I tested this out with a smaller set of tiles and the memory used by imagecreatetruecolor() and I estimate I need 2.7GB

Answer 1

You're running on a 64-bit operating system, but Apache and PHP are likely still 32-bit. If you're using mod_php, apache would be the limiting factor here.

32-bit processes are limited about 2GiB of RAM unless you used the /3GB switch and the software is aware of 3GB support.

That still leaves up about 200 MiB that seems unused, but its small enough that it can be used by various libraries that all have to be loaded in memory

As far as I know, the library usage won't show up in the committed memory, but still counts towards the 2GiB limit (much like device memory counts towards the 4GiB limit on 32-bit windows. Where installing 2 GiB graphics card brings you down to under 2GiB of usable RAM).

Most likely solution? Install a 64-bit PHP, and then dispatch it to that (using a system() call, perhaps)

Answer 2

Using Acquia Dev Desktop, I had many memory limit crashes.

After having increased the memory limit into PHP.ini.

php_value memory_limit                  1024M
php_value max_execution_time            3000

This issue was less frequent but still occuring ( Especially with Feature Recreate )

Into my httpd.conf I increased the StackThread to 16M

ThreadStackSize 16*1024*1024

And it solved the memory crash issue. Hope it can help

Answer 3

Which PHP version are you using?

The memory_limit variable is, or was, contained in a 32-bit integer, so can not go above 2GB.

See: http://bugs.php.net/bug.php?id=39132&edit=1

From the bottom comment on that bug report, it might be the routine that translates the human readable form to a number, try putting it in digits.

Answer 4

Check your Apache config (e.g., httpd.conf). There's likely an RLimitMEM directive limiting the memory allow for children processes handling requests.

So, you can set your PHP limit all you want, if Apache spawns the process with a memory limit, you can't exceed that.

If you're on a hosted service and have a shared server, likely you don't have access to this config and need to work with your provider. As you can see, it's configuration that applies server-wide... you're not likely going to get them to change this. Then again, if you're looking to spawn bigger than 1.5Gig processes, you prolly should be either solving the problem a different way (others have suggested this) or getting a dedicated server of some kind (e.g. EC2).

For example:

/usr/local/apache/conf
#RLimitMEM 85643200 104857600   # Limit to: 80Mb / process, 100Mb total
RLimitMEM 134217728 537395200   # Limit to: 128Mb / Process, 512Mb total

Answer 5

The issue is likely to be caused by running 32-bit apache and php. Try upgrading these to 64-bit binaries and see if that fixes the issue.

Answer 6

Try this

set_time_limit(300);
ini_set('memory_limit', '20000M');

Answer 7

Try this:

#php_value memory_limit 300M 
#php_value upload_max_filesize 200M 
#php_value post_max_size 200M 
#php_value max_execution_time 80000 
#php_value max_input_time 80000   

Answer 8

try ini_set('memory_limit', '-1');