At Tuesday 2003/02/25 08:26, you wrote:
Russell Hind said: > Is yield intended to always yield to another thread if one can run? > Because the code for yield is > > void thread::yield() > { > #if defined(BOOST_HAS_WINTHREADS) > Sleep(0); > #elif defined(BOOST_HAS_PTHREADS) > # if defined(BOOST_HAS_SCHED_YIELD) > int res = 0; > res = sched_yield(); > assert(res == 0); > # elif defined(BOOST_HAS_PTHREAD_YIELD) > int res = 0; > res = pthread_yield(); > assert(res == 0); > # else > xtime xt; > xtime_get(&xt, TIME_UTC); > sleep(xt); > # endif > #elif defined(BOOST_HAS_MPTASKS) > MPYield(); > #endif > } > > Taken from the main CVS. > > Sleep(0) on Win32 will only yield to another thread of equal or higher > priority, not to lower priority threads. > > In boost::detail::lightweight_mutex::scoped_lock, it is mentioned that > Sleep(1) will get around. Is the behaviour of Sleep(0) the intended use > of yield? > > explicit scoped_lock(lightweight_mutex & m): m_(m) > { > while( InterlockedExchange(&m_.l_, 1) ) > { > // Note: changed to Sleep(1) from Sleep(0). > // According to MSDN, Sleep(0) will never yield > // to a lower-priority thread, whereas Sleep(1) > // will. Performance seems not to be affected. > > Sleep(1); > } > } > > (I don't actually use yield yet, so currently have no preference for > either, but just wondered what the intended use of yield was)
I'll look into this and fix it. Thanks.
-- William E. Kempf
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Victor A. Wagner Jr. http://rudbek.com The five most dangerous words in the English language: "There oughta be a law"
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