Imagemagick only uses one core

Question

I am running an Ubuntu server with 8 cores. However imagemagick always only uses 1 single core.
Running identify -version returns:

Version         


        

Answer 1

I was able to reproduce this behavior on Ubuntu 10.04. ImageMagick from apt-get seems to have the OpenMP feature, and configure with the -fopenmp flag, but the feature doesn't seem to be enabled. This can be verified by running the following line, and comparing the "FEATURES" list (if present) to the various configuration flags.

identify -list Configure | less

I was able to resolve this by following the article "Installing ImageMagick from Source on Ubuntu 8.04" which detailed the following process.

• Remove ImageMagick
• Install all the needed image/graphic dependency libraries through apt-get
• Download
  • wget http://www.imagemagick.org/download/ImageMagick-6.8.6-6.tar.gz
• Follow basic ./configure, make, & sudo make install steps
• Export library path to /usr/local/lib

This seems to work as OpenMP is now present under "FEATURES" list, and when I execute convert logo: -resize 500% -bench 10 logo.png. I see the following

Performance[1]: 10i 0.750ips 1.000e 18.750u 0:13.330
Performance[2]: 10i 0.751ips 0.500e 18.660u 0:13.320
Performance[3]: 10i 0.738ips 0.496e 18.840u 0:13.550
Performance[4]: 10i 0.469ips 0.385e 19.560u 0:21.320

And these results match what I would expect.