Thread Safety for SURF.create(...)

I have noticed that with a high computing load (LoadAvarage from 30 and higher) the detector is created, but undefinable errors occur when I use it. All input parameters (of the detector at create and the images) are identical.

SURF detector = SURF.create(...)

Has anyone else noticed this?

I use 4.6.0 on Linux.

Here is my first troubleshooting question about it: