Got the following error while loading thumbnail images in a wiki installation.
Error creating thumbnail: libgomp: Thread creation failed: Resource temporarily unavailable
The issue was with only a couple of images and others were working fine.
The issue might be with the wgMaxShellMemory parameter in the media wiki configuration. Check the configuration file for this.
# vi includes/DefaultSettings.php
Increased the parameter value $wgMaxShellMemory and the images started loading fine.
If this doesn’t worked, you can also try increasing the shell execution (wgMaxShellFileSize) value in the above file.