Should I always destroy Imagick objects?

Question

Imagick has two methods: clear () and destroy ().

But I'm not sure when to use them.

For example, do I need to destroy () even after rewriting the only link I have?

$img = new Imagick($path1); // do something with $img, then load a different image $img = new Imagick($path2); // should I have destroyed $img before doing this? 

Does Imagick free resources if I rewrite a link?

If not, it is both annoying and scary.

Answer 1

I did a quick and dirty test, image1 - 85kb image2 - 457kb

 $start = microtime(); for($i=0; $i<10; $i++){ $img = new Imagick('./image1.jpg'); $img->setImageResolution(72,72); $img->resampleImage(72,72,imagick::FILTER_UNDEFINED,0); $img->destroy(); $img = new Imagick('./image2.jpg'); $img->setImageResolution(72,72); $img->resampleImage(72,72,imagick::FILTER_UNDEFINED,0); $img->destroy(); } $end = microtime(); $len = $end - $start; echo number_format($len, 2),'<br /> <br />'; function kb($n){ return ceil($n/1024); } echo 'memory usage - ',kb(memory_get_usage()),' / ',kb(memory_get_peak_usage()),' <br />'; 

And then I commented out the destruction lines and ran it again. it seemed strange that using destroy() uses more memory, but only 3 or 4 k. the timer was no different, and when I ran the basic load test on the apache platform

 ab -n 20 -c 5 http://ubunty.local/sandbox/stackexchange/imagick.php 

It did not seem to have much.

I expected to destroy less memory. even using image2 in another variable doesn't seem to matter

 $img2 = new Imagick('./image2.jpg'); 

If there is a reason to use → destroy (), then as far as I can tell, this should be to the point that I forgot to measure.