I didn't realize that it was already implicitly sorted by time. Thanks for answering
在2023年6月6日星期二 UTC+8 00:27:51<Ian Lance Taylor> 写道： > On Mon, Jun 5, 2023 at 5:08 AM fliter <imc...@gmail.com> wrote: > > > > Thanks for your answer. But I wonder if the elements behind the queue > may wait for a very long time? Can we maintain a waiting time after > entering the queue for each coroutine, and acquire locks from high to low > > The queue is already FIFO ordered. The goroutine at the head of the > queue is the one that has been in the queue the longest. I don't see > what benefit we would get from recording a waiting time with the > queue. > > Ian > > > > > > 在2023年6月4日星期日 UTC+8 01:07:52<Ian Lance Taylor> 写道： > >> > >> On Sat, Jun 3, 2023 at 12:35 AM fliter <imc...@gmail.com> wrote: > >> > > >> > > >> > In sync/mutex.go, there is a comment like the following: > >> > > >> > ```go > >> > // Mutex fairness. > >> > // > >> > // Mutex can be in 2 modes of operations: normal and starvation. > >> > // In normal mode waiters are queued in FIFO order, but a woken up > waiter > >> > // does not own the mutex and competes with new arriving goroutines > over > >> > // the ownership. New arriving goroutines have an advantage -- they > are > >> > // already running on CPU and there can be lots of them, so a woken up > >> > // waiter has good chances of losing. In such case it is queued at > front > >> > // of the wait queue. If a waiter fails to acquire the mutex for more > than 1ms, > >> > // it switches mutex to the starvation mode. > >> > ``` > >> > > >> > > >> > I wonder if the waiter here refers to the goroutine at the head of > the queue, or any goroutine in the queue? > >> > >> In that comment "waiter" refers to the goroutine at the head of the > >> queue. When a mutex is unlocked, it wakes up the first waiter, if > >> any. > >> > >> Ian > > > > -- > > You received this message because you are subscribed to the Google > Groups "golang-nuts" group. > > To unsubscribe from this group and stop receiving emails from it, send > an email to golang-nuts...@googlegroups.com. > > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/8a9dd408-a4cc-45e6-b806-e8a25cb4e309n%40googlegroups.com > . > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/7e4dcf3c-ad5f-42e8-bb39-4892d5f085a6n%40googlegroups.com.
