Image: Image::encode() leaks memory

Created on 17 Sep 2015 · 8Comments · Source: Intervention/image

Hey, I'm working on a batch script that processes lots of images in a loop, always crashing due to memory exhaustion caused by intervention/image. Here is a very simplified script that reproduces this problem:

use Intervention\Image\ImageManager;

$manager = new ImageManager(array('driver' => 'gd'));

for ($i = 0; $i < 1000; $i++) {
    $image = $manager->make(__DIR__ . '/image.png');
    $image->encode('jpg');
    echo "$i. " . memory_get_peak_usage(true) . "\n";
}

I've traced this problem to this assignment https://github.com/Intervention/image/blob/master/src/Intervention/Image/AbstractEncoder.php#L87, which I believe creates a circular reference between the Image and Encoder instances, causing the memory to never be freed.

Simply unsetting the $this->image reference after the image is encoded fixes this problem.

public function process(Image $image, $format = null, $quality = null)
{
        ...

        $this->setImage(null);

        return $image->setEncoded($this->result);
}

Source

itsgoingd

All 8 comments

I would use destroy() to free memory in each iteration. Unsetting the image after encoding, might not be always wanted.

olivervogel on 18 Sep 2015

👍1

That doesn't fix the problem, it still leaks, just a lot less. Better workaround is to call gc_collect_cycles() in each iteration, it's still just a workaround though, end user shouldn't be expected to do this.

itsgoingd on 18 Sep 2015

👍1

So this seems to be a problem of the GD function. Or is it the code from Intervention Image leaking memory?

olivervogel on 19 Sep 2015

This is an issue with Intervention Image itself (it can be reproduced with both gd and imagick), I believe what is happening is:

on Image::make call an Image and Driver instances are created and reference to a Driver instance is stored as Image::$driver
new Encoder instance is created in the Driver constructor and stored as Driver::$encoder
on Image::encode call the Image instance is passed to Encoder::process, where it is stored as Encoder::$image (I guess this is done for convenience, so the Image instance doesn't have to be passed as argument all over the place)
now when I'm done with saving the encoded image and I unset the Image instance in my client-code (and I expect the memory to be freed at that point) a reference to the Image instance still exists in Encoder::$image, which itself isn't freed because it's referenced in Driver::$encoder which is referenced in Image::$driver - basically creating circular reference between the Image and Encoder instances

That's why unsetting the Image reference in Encoder::process after it's no longer needed fixes the problem. Unsetting Image reference in my client-code in that case frees the memory as no other references for that object exist at that point.

I hope that makes at least some sense, I'm pretty awful at explaining stuff. :)

itsgoingd on 23 Sep 2015

👍1

abhimanyu003 on 9 Oct 2015

I can confirm that $this->setImage(null); fixes also the problem for Imagick.

Test case using this picture (on the filesystem):

require 'vendor/autoload.php';

use Intervention\Image\ImageManager;

$manager = new ImageManager(array('driver' => 'imagick'));

for ($i = 0; $i < 10; $i++) {
    $image = $manager->make(__DIR__ . '/lichtenstein.jpg');
    $image->encode('png');
    $image->destroy();
    echo "$i. " . memory_get_peak_usage(true) . "\n";
}

Output without $this->setImage(null);: