Handle to a figure, axes, uipanel, or image graphics object, specified as a handle. If h is an axes or figure handle containing multiple images, then getimage uses the first image returned by findobj(h,'Type','image').
getimage
I tried to reproduce the error with a simple test script that only calls getimagesize() with the given URL - but this not crash. It simple leads to an exception saying that the URL could not be loaded (which is fine as the URL is wrong)
The problem turned out to be a call to getimagesize (in my case around line 72 in lib/Varien/Image/Adapter/Gd2.php). Even though the image file in question was located on the site itself, the parameter to getimagesize was an HTTP URL. Because of a weird firewall configuration, the server was unable to contact itself via HTTP, so request hang and for reasons unknown, php-fpm stopped serving requests all together.
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