Monty and I had an argument recently regarding pthread_yield() and std::this_thread::yield() usage. I do want to make this discussion public, so that we can pick either approach, get it documented and make sure everybody is aware of reasoning and decision. Probably even add a bb check that wouldn't allow unwanted function calls to pass. Lets try to keep this discussion focused on std::this_thread::yield() and avoid discussing other C++11 features. Since I'm biased towards std::this_thread::yield() I'd let Monty elaborate his concerns and explain why he prefers pthread_yield(). But generally it comes to compatibility and portability. My position is: pthread_yield() should be removed in favour of std::this_thread::yield(). Benefits: 1. Must be available to all current MariaDB versions. C++11 is a must since 2018. 2. Compatibility and portability, which we don't have to care about. 3. I have no performance concerns after analysing how it is implemented by clang and gcc. 4. Goes inline with "MDEV-35461 - Remove redundant checks for standard library functions" 5. Standard things looks more community-friendly, e.g. why should MSVC developers care about POSIX threads? Currently pthread_yield() can be defined to: 1. SwitchToThread() - Win32 (Wlad, 2009) MSVC seems to support std::this_thread::yield() since 2015: https://learn.microsoft.com/en-us/cpp/standard-library/thread-functions?view... 2. thr_yield() - Solaris (Serg, 2009) Oracle Developer Studio 12.6 supports std::this_thread::yield() since 2017: https://docs.oracle.com/cd/E77782_01/html/E77789/bkabe.html#OSSCPgnyio 3. pthread_yield_np() - OS X (Serg, 2009) XCode is based on clang, which supports std::this_thread::yield() since 2013. sched_yield() - default (Serg, 2009) pthread_yield() - deprecated since 2021 (Serg, 2009) Possible concerns: 1. Compatibility with recent platforms. C++11 is widely available, thread models seem to be well supported. InnoDB uses std::this_thread_yield() since 2021. 2. Compatibility with older (ancient?) platforms. We're way off into C++11 since 2018. Making recent MariaDB compile on such platforms is probably going to be a heavy effort. If we do really want to have these platforms supported, they must be present in buildbot. 3. Performance impact of std::this_thread::yield(). See below. In many cases it is just a wrapper around functions like sched_yield. clang: libcxx/include/__thread/this_thread.h:inline _LIBCPP_HIDE_FROM_ABI void yield() _NOEXCEPT { __libcpp_thread_yield(); } libcxx/src/support/win32/thread_win32.cpp:void __libcpp_thread_yield() { SwitchToThread(); } libcxx/include/__thread/support/pthread.h:inline _LIBCPP_HIDE_FROM_ABI void __libcpp_thread_yield() { sched_yield(); } gcc additionally supports VxWorks: yield() noexcept { #if defined _GLIBCXX_HAS_GTHREADS && defined _GLIBCXX_USE_SCHED_YIELD __gthread_yield(); #endif } int __gthread_yield (void) { return taskDelay (0); } __GTHREAD_INLINE int __gthread_yield (void) { return __gthrw_(sched_yield) (); } Regards, Sergey