"Quit thread"

- this is interesting. It looks like you are quiting the thread that spawned jobs before it has the chance to finish.

Is not it possible that you are calling Finish (perhaps via ~CoWork) from other thread than the one that scheduled the work? Or in other words, have CoWork instance shared between threads?

It is true that between 'classic' and 'C++11' I have changed the logic so that each 'master thread' has its own pool of worker threads, to avoid work stealing. Perhaps it was not a good idea after all..