Question

Basically I am developing an opencv application. I have built OpenCV with_tbb option in cmake.

I would like to use intel tbb to run a parallel thread that at some intervals updates some global variables. Something like:

vector<int> mySharedVar;

void secondaryThreadFunction() {
 while(true) {
   Do some operations
   And update mySharedVar if necessarily  

   usleep(1000);
 }
}

int main() {
   run in parallel secondaryThreadFunction;

   in the master Thread keep doing something based on mySharedVar

   while(true) {
    do something;
   }
}

How can I run secondaryThreadFunction() on another thread ?

Answer 1

Intel TBB is not meant to be used for that kind of purpose.
Quote from the Tutorial:

Intel® Threading Building Blocks targets threading for performance.
Most general-purpose threading packages support many different kinds
of threading, such as threading for asynchronous events in graphical
user interfaces. As a result, general-purpose packages tend to be
low-level tools that provide a foundation, not a solution. Instead,
Intel® Threading Building Blocks focuses on the particular goal of
parallelizing computationally intensive work, delivering higher-level,
simpler solutions.

The thing you wanna do can be easily achived with either boost::thread or the C++11 threading features:

   // using async
   auto fut = std::async(std::launch::async, secondaryThreadFunction);
   // using threads (for boost, just replace std with boost)
   std::thread async_thread(secondaryThreadFunction);

   in the master Thread keep doing something based on mySharedVar

   while(true) {
    do something;
   }

   // in case of using threads
   async_thread.join();

Keep in mind to sync the access to any shared variables.