using TBB for non-parallel tasks

Question

I want to get a thread-pool behavior using TBB. But whenever I read documents about TBB they always talk about parallel-for, parallel-dowhile etc. In contrast what I need is a main thread to assign tasks to a thread pool so those tasks will be executed 'on their own' - execute tasks asynchronously. Tasks here can be event handling for a GUI.

Is the TBB task scheduler appropriate for such behavior? The impression I got from task scheduler is that it's only beneficial if I have tasks that can be broken down and executed in parallel to each other.

Download the "Design Patterns" guide from http://threadingbuildingblocks.org/documentation.php. It specifically mentions offloading long-running tasks from the GUI thread (see Chapter 8, "GUI Thread"), and has a simple example showing how it's done. — Jim Mischel, Nov 28 '11 at 20:41

score 10 · Accepted Answer · edited Mar 12 '14 at 03:58

Starting from version 3.0, TBB has support for asynchronous execution of tasks. For that, a special work offering method tbb::task::enqueue() was added. Unlike tbb::task::spawn(), this method guarantees that the enqueued task will be executed even if the originating thread never enters a task dispatch method such as wait_for_all().

A short usage example for task::enqueue():

class MyTask : public tbb::task {
    /*override*/ tbb::task* execute() {
        // Do the job
        return NULL; // or a pointer to a new task to be executed immediately
    }
};

MyTask* t = new (tbb::task::allocate_root()) MyTask();
tbb::task::enqueue(*t);
// Do other job; the task will be executed asynchronously

As @JimMishell mentioned in the comment, an example how to use it for handling of GUI events can be found in "Design Patterns"; and the formal description of the method is available in the Reference manual (see TBB documentation for both).

using TBB for non-parallel tasks

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