if i allocate more than 5501 threads, subsequent threads fail to run. these threads live a very short time and only maybe ten max are alive at any one time. for example if i'm iterating over every song in my music library and doing some quick process, after about 5500 songs, the program stops working. i'm exiting the threads normally, so housekeeping is performed (tho it would be performed anyway, right?) i checked and when it crashes there are indeed only about five threads running. so SOME resource is not getting released, it's not my resource, it's something to do with boost::threads. as a test, i created one thread, then on that thread i loop and create 30,000 threads. the only thing the thread does is increment a counter and exit, so no more than a couple threads are live at once. why is it throwing an exception?? call stack: #0 0x001cebaf in boost::detail::sp_counted_impl_p<boost::detail::thread_data<CFork_Preemptive> >::sp_counted_impl_p at sp_counted_impl.hpp:67 #1 0x001cec0f in boost::detail::shared_count::shared_count<boost::detail::thread_data<CFork_Preemptive> > at shared_count.hpp:87 #2 0x001d008a in boost::shared_ptr<boost::detail::thread_data_base>::shared_ptr<boost::detail::thread_data<CFork_Preemptive> > at shared_ptr.hpp:187 #3 0x001d0110 in boost::thread::make_thread_info<CFork_Preemptive> at thread.hpp:136 #4 0x001d0149 in boost::thread::thread<CFork_Preemptive> at thread.hpp:186 #5 0x001c6e92 in CThreads::Fork at CThreads.cpp:765 template<class X> class sp_counted_impl_p: public sp_counted_base { private: X * px_; sp_counted_impl_p( sp_counted_impl_p const & ); sp_counted_impl_p & operator= ( sp_counted_impl_p const & ); typedef sp_counted_impl_p<X> this_type; public: explicit sp_counted_impl_p( X * px ): px_( px ) { <<--- throw happens right here #if defined(BOOST_SP_ENABLE_DEBUG_HOOKS) boost::sp_scalar_constructor_hook( px, sizeof(X), this ); #endif } virtual void dispose() // nothrow { #if defined(BOOST_SP_ENABLE_DEBUG_HOOKS) boost::sp_scalar_destructor_hook( px_, sizeof(X), this ); #endif boost::checked_delete( px_ ); }