Wand silently crashes if hugging face transformers library is imported immediately before Wand import

[matoles]

The following code behaves as expected:

from wand.image import Image # MUST BE RUN BEFORE `from transformers import ... ` or will produce silent failure
from transformers import PreTrainedTokenizer # MUST BE RUN AFTER `from wand.image import... ` or will produce silent failure

with Image(filename='/path/to/filename.pdf') as wand_img:
    for page in wand_img.sequence:
        page_img = Image(page)
        print('foo')

However, if the libraries are imported in the opposite order, Wand will silently terminate on line 6:

from transformers import PreTrainedTokenizer # MUST BE RUN AFTER `from wand.image import... ` or will produce silent failure
from wand.image import Image # MUST BE RUN BEFORE `from transformers import ... ` or will produce silent failure

with Image(filename='/path/to/filename.pdf') as wand_img:
    for page in wand_img.sequence:
        page_img = Image(page) # crashes
        print('foo')

transformers version 4.6.1
Wand version 0.6.6

[emcconville]

Works as expected for me on Fedora with both ImageMagick 6 & 7. However, PDF & Image.sequence can be very resource intensive. Try converting each page in the PDF document to an image on disk without the RAM overhead.

with Image(filename='/path/to/filename.pdf') as wand_img:
   wand_img.save(filename='/path/to/page-%04d.png')

[matoles]

Good to know.

Maybe it's OS specific. My specs:
macOS Big Sur
v11.2.3
Chip: Apple M1
Memory: 16GB

[alext]

I think this may be caused by pytorch (a dependency of transformers) bundling its own version of libiomp5.

I've been hitting segfaults if torch is imported before wand on macs recently. This started when the system libomp was been upgraded to 12.0.0 (from homebrew). Debugging the stacktrace revealed that libiomp5 bundled with torch was in the call stack. I just raised this as an issue against pytorch here: pytorch/pytorch#60094

[emcconville]

Good point @alext ! Mixing OpenMP & OpenCL libraries can be deadly. As wand loads libraries through ctypes, there's no way to control what linked dylib/so are previously loaded. There could also be a issue with Apples M1 chip, but without the developer transition kits available, I could only guess.

[emcconville]

Rebooting this issue after a year. Can anyone with a M1 chip retest this with the latest master branch?