Yeah the default behavior is to switch back. It’s possible to pin a goroutine to a thread with runtime.LockOSThread(). However I don’t believe it avoids the stack switching. It’s purpose it to make sure that Thread Local Storage works properly. The runtime is pretty smart though so it might already do the optimization you suggested in someway. I know it has a goroutine specifically for monitoring if a thread is stuck in a external call and therefore spawns a new thread to continue work (sysmon)