<p dir="auto">I am using multiprocessing to speed up ARUCO target detection on a raspberry pi.<br>
(Keep in mind I have gotten this working using no multiprocessing.)</p>
<p dir="auto">Using this code:<br>
``<br>
workers = []<br>
for i in range(num_workers):<br>
workers.append(Worker_Bee(tasks,results,i))</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="for worker in workers:
    worker.start()  

for i in range(20):
    tasks.put(Image_Processor(vs.read()))
    time.sleep(.5)"><pre class="notranslate"><code class="notranslate">for worker in workers:
    worker.start()  

for i in range(20):
    tasks.put(Image_Processor(vs.read()))
    time.sleep(.5)
</code></pre></div>
<p dir="auto">``<br>
The Image_Processor looks at the frame vs.read() which is an image. The image processor tries to find targets in the image.<br>
The worker process Image_Processor hangs on the following line:<br>
corners, ids, rejectedImgPoints = aruco.detectMarkers(gray, self.aruco_dict, parameters=self.parameters)<br>
where gray is the image vs.read()<br>
I've check the arguments to aruco.detectMarkers and they seem to be correct (and as I've said before, I've ran this before without multiprocessing fine).<br>
There is no error message, and looking at top, I see the python process spawning but then quickly going away. The parent process stays.</p>
<p dir="auto">I've seen similar problems with openCV hanging on cvtColor or resize, but all of their problems are fixed for me (compiling with TBB options and such).</p>
<p dir="auto">Any advice on how to get this working?</p>
<h5 dir="auto">System information (version)</h5>
<ul dir="auto">
<li>OpenCV =&gt; 4.0.1</li>
<li>Operating System / Platform =&gt; Windows UWP (Hololens)</li>
<li>Compiler =&gt; Visual Studio 2017</li>
<li>CMake GUI =&gt; 3.14.2</li>
</ul>
<h5 dir="auto">Detailed description</h5>
<p dir="auto">Hi,</p>
<p dir="auto">I am able to build the OpenCv 4.0.1 with extra contrib for x86 and x64 on desktop.<br>
However failed for UWP platform on windows 10.</p>

<h5 dir="auto">Steps to reproduce</h5>
<p dir="auto">Fallowed steps as per the below link.</p>
<p dir="auto"><a href="https://medium.com/@rabbi.cse.sust.bd/how-to-build-opencv-for-universal-windows-platform-uwp-1a642ec09955" rel="nofollow">https://medium.com/@rabbi.cse.sust.bd/how-to-build-opencv-for-universal-windows-platform-uwp-1a642ec09955</a></p>
<p dir="auto">After fallowing steps CMake generate project successfully with extra contrib .</p>
<p dir="auto">When try to build the solution the module compilation fails.</p>