Question

I’m trying to port a C# thread pool into C++ but have encountered some serious problems. Some of the features of the C# thread pool are:

1. Define the maximum number of concurrent threads explicitly
2. Each thread is defined using a AutoResetEvent
3. Each workitem in the thread are overloaded so that it can have delegate functions as its private members.

For example,

private static void RunOrBlock(WorkItem workitem) {
  workItem.ThreadIndex = WaitHandle.WaitAny(threadUnoccupied);
  ThreadPool.QueueUserWorkItem(threadWorker, workItem);
}

private static void threadWorker(object o) {
  WorkItem workItem = (workItem) o;
  workItem.Run();
  threadUnoccupied[workItem.ThreadIndex].Set();
}

WorkItem is defined as:

public abstract class WorkItem {
  protected int threadIndex;
  public abstract void Run();
  public int ThreadIndex {
    get { return threadIndex; }
    set { threadIndex = value; } 
  }

Does someone know if there exists a open-source threading pool that has similar functionalities? If not, what will be the correct way to implement such a threading pool? Thanks!

Answer 1

I’m not certain about their specific functionalities, but for open source threadpools in c++ look at boost threadpool or zthreads.

If you just need a threadpool like functionality and have a compiler which supports it, you could also just use openmp 3.0 tasks. This is what I would choose if possible, since "boost" threadpool didn’t look very convincing at a glance (so might have quite a bit of overhead) and it seems like zthreads isn’t actively developed anymore (at least at first glance, I’m not 100% sure).

In the not exactly foss, but might be usable if you can live with the licensing (or are ready to invest quite a bit of money…) Intel Threading Building Blocks is pretty much treadpool based