OpenMP support

[BenMorel]

Hi,

I've noticed that all my Gmagick code runs on a single CPU core, which is a pity on servers with 8 cores or more, given that GraphicsMagick supports OpenMP.

Is there a reason for this? Imagick leaves the choice to enable OpenMP, can we do the same for Gmagick?

[Danack]

Gmagick does not do any processing itself - it passes all image processing to GraphicsMagick

If you have compiled GraphicsMagick with OpenMP enabled, probably with the --enable-openmp flag set, and with a suitable version of OpenMP installed, it should 'just work'.

However.....you really ought to test it. I am not convinced OpenMP is stable either with ImageMagick or GraphicsMagick. At least for me I was seeing weird shutdown errors in PHP when OpenMP was enabled.

[BenMorel]

As mentioned in greater details in my question on StackOverflow, I did compile GraphicsMagick with OpenMP (configure --enable-openmp --enable-shared, make, make install, and then Gmagick against it (phpize, configure, make), but Gmagick was still using a single core, as far as I could see!

[Danack]

To be clear, Gmagick doesn't really touch the threads. If you've compiled with OpenMP enabled for GraphicsMagick, then it should 'just work' for Gmagick.

There is a function to set the resource limit, what happens when you call it?

$gmagick->setResourceLimit(\Gmagick::RESOURCETYPE_THREADS, 4);

not saying it will work - it should be working by default.

Actually, the result of getResultLimit would be interesting as well.

[BenMorel]

Hi, sorry I'm a bit (18 months) late. Coming back to this. I tried:

$gmagick->getResourceLimit(Gmagick::RESOURCETYPE_THREADS);

But I get an error:

Undefined class constant 'RESOURCETYPE_THREADS'

Could this be why OpenMP is not used in Gmagick?

Looking at the source code, this constant is available when ThreadsResource is defined. How does it get defined?