Hello,

I am looking for a way to interrupt a QtConcurrent::blockingMap's job. I tried calling clear() on the QThreadPool's global instance, but it doesn't work as I expected. Here is a minimal example showing what I'm trying to do.

Qt Code: 
  1. #include <QtConcurrent>
  2. #include <QThreadPool>
  3.  
  4. #include <vector>
  5.  
  6. int main(int argc, char ** argv)
  7. {
  8.   std::vector<int> ones(100, 1);
  9.   ones[10] = 123; // special value
  10.  
  11.   QThreadPool::globalInstance()->setMaxThreadCount(1);
  12.  
  13.   auto times_two = [](int & i)
  14.   {
  15.     if (i == 123) // when reaching the special value, I want to stop the other jobs here
  16.       QThreadPool::globalInstance()->clear();
  17.     else
  18.       i *= 2;
  19.   };
  20.  
  21.   QtConcurrent::blockingMap(ones.begin(), ones.end(), times_two);
  22.  
  23.   return 0;
  24. }
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Here, each value inside a vector is multiplied by 2, until a special value (123) is found. Then, the call to clear() seems to have no effect whatsoever, i.e. the lambda "times_two" is called on the rest of the vector. But according to the documentation, QThreadPool::clear() is supposed to "remove the runnables that are not yet started from the queue".

Is there something I am doing wrong here ?

Thanks.