Question

I have to render something with Imagick on PHP CLI.
I have noticed that every 3-5 days the server memory gets full, so i can’t even connet via ssh or ftp.

with memory_get_usage() i narrwoed the memory leak down to the imagick part of the script.
the script looks something like this:

$sourceImg = 'source.png';
$destImg = 'dest.png';
$background ='#00ff00';

$im = new Imagick();
$im->pingImage($sourceImg);
$im->readImage($sourceImg); 
$draw = new ImagickDraw();

for($i=1;$i<=5;$i++){
    $draw->setFillColor( $background);
    $draw->rectangle( 10*$i+5, 10, 10*$i+10, 20);
} 

$im->drawImage( $draw );
$im->writeImage( $destImg );
$im->destroy();

unset($im,$draw);

I destroy the image reference, and unset the imagick and imagickDraw object, but the script won’t release any memory.
The setFillColor() method takes the most memory

Can i do something else to free the space used by imageick?

image of the memory consumption

Answer 1

imagick uses a shared library and it’s memory usage is out of reach for PHP, so tuning PHP memory and garbage collection won’t help.

I had the same problem myself, trying to handle a multi-page-tiff image with 50 (!) pages of 3000×2000 pixels.
The solution is to have imagick put its pixel cache on disk.

Adding this prior to creating the Imagick object solved the problem for me:

// pixel cache max size
IMagick::setResourceLimit(imagick::RESOURCETYPE_MEMORY, 256);
// maximum amount of memory map to allocate for the pixel cache
IMagick::setResourceLimit(imagick::RESOURCETYPE_MAP, 256);

The goal is to make imagick put its pixel cache on disk instead of in RAM. The default place seems to be files /tmp/magick-XXnnnnn, so make sure /tmp is not on shmfs/ramdisk, or change the temp directory imagick uses.

Other resouce limits to investigate: imagick::RESOURCETYPE_DISK, imagick::RESOURCETYPE_FILE, and imagick::RESOURCETYPE_AREA.
They are described in the imagick::getResourceLimit() manual page (not so well in the page for setResourceLimit()).

In my image handling loop, I have set_time_limit(300), since the script takes ages to process this huge (when uncompress) image.

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EDIT : In recent versions, setResourceLimit() should not be called as a static method, but on the actual object instead, such as:

$im->setResourceLimit(imagick::RESOURCETYPE_MEMORY, 256);
$im->setResourceLimit(imagick::RESOURCETYPE_MAP, 256);
$im->setResourceLimit(imagick::RESOURCETYPE_AREA, 1512);
$im->setResourceLimit(imagick::RESOURCETYPE_FILE, 768);
$im->setResourceLimit(imagick::RESOURCETYPE_DISK, -1);