Batch generator hangs with multithread

[23pointsNorth]

When using alongside the keras ImageDataGenerator with multithreading=True, the process hangs on recv(). Switching the number of workers to 0 (i.e. no multithread) works as expected.

Versions:
imgaug: 0.2.5 (from master 13May18)
python: 3.5
keras: 2.1.3

I saw the last merged PR #126 tacking in the same direction, and have confirmed that the installed version has it, but problem persists.

[aleju]

Do you maybe have a minimal working example? It's fairly hard to test for these rare cases, even more so when a different library is added to the mix.

[mmisono]

I encountered the similar problem (Python 3.6, imgaug 0.2.5, Ubuntu 16.04).
After some investigation, I found that cv2.resize() called in the imgaug.augumenters.Scale() hangs.
It seems OpenCV has some multithreading issue.

In my environment, calling cv2.setNumThreads(0) fixes the problem (though in this case obviously OpenCV use only one thread..)

Possibly related thread: opencv/opencv#5150

[mmisono]

related: pytorch/pytorch#1355