My code is in C++; I am using thread_group directly. The thread group call a function member of the same class. In side this function member I called another class's function member to finish the task. The task is completely "embarrassingly parallel", thus I expect it scale very well. But it didn't, the performance of my code I describe above is even worse than when I use boost thread to call a executable instead of the function member of the same class. I don't understand what's going on. Any suggestions are really appreciated!!! -- View this message in context: http://old.nabble.com/Performance-problem-with-boost-thread-tp26779904p26779... Sent from the Boost - Dev mailing list archive at Nabble.com.