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I was revisiting a code which had a parallel_while and wanted to do same thing explicitly instead of using parallel_while (since that being deprecated). What I understood from the source for parallel_while is that it creates an empty task and makes every new task a child of that root empty task and waits on the root, which acts like a barrier. In my code to achieve the same, I have created a root empty task, generated by the master thread. Then, I allow multiple threads to create new tasks and add it as a child to the root. When I want to join, I wait on the root empty task. This works fine, however I am having trouble understanding why, my assumption would be that it should not have. Let me elaborate my confusion below.

Now when a thread wants to add a new child to the root, it needs a running task on that thread to do so (if I am not mistaken). My question is: How does a thread make a task an additional child of the root before starting running a task? When an initialize the task scheduler every thread should have null for tbb::task::self() (The master thread is running but since what it is doing is not a tbb::task, self() should be null for that, too). If that is the case, how is the very first job start executing?

Sagnak