OpenCV in parallel threads
I'm writing a multithreaded application (Linux, OpenCV 3.4), where the captured image is processed in parallel threads, each doing a different type of processing on a copy of the image. The two threads don't share any variables, so normally there is no concurrence problem.
One of the threads calculates a optical flow (using calcOpticalFlowPyrLK), the other contains a connectedComponentsWithStats function.
However, if during the processing the CPU usage reaches 100%, the calcOpticalFlowPyrLK function hangs (it won't return).
If I comment either the calcOpticalFlowPyrLK or the connectedComponentsWithStats function (or disable one of the two threads), I don't have any hangups, so I suspect this might be the problem. The other OpenCV functions I use are not multithreaded AFAIK.
[I compiled OpenCV with TBB support for parallelization (OpenCL, Cuda and OpenMP are not enabled). As my program is in C++/Qt, I use QThread for multithreading.]
EDIT The problem persists if OpenCV is compiled without TBB support...
Do you have any ideas what can be the problem?
Can you specify compiler, exact version (if it's 3.4.3 ect), did you build it yourself from source, exact compiler flags.
If possible, can you make a tiny sample that produces the same result?