Pathos.multiprocessing raised the message "Aborted system call"

I have written some code that uses multiprocessing. I posted the code here . Now the code is working fine and I got the final results, even the last part of the graph is done, but with an error message at the end:

Exception OSError: (4, 'Interrupted system call') in <Finalize object, dead> ignored

      

        
        
        
      

    

I don't know why this error message happened. Can anyone explain this?