On Friday, 21 October 2016 09:05:10 UTC-4, Michael Liu wrote: > > I've a race scenario used with Mutex.Lock with Lock() and Unlock(). now > multi-routines try to lock the resource and start a few logical code if the > Lock.Lock() succesfully. other routines don't need to block util > Lock.Unlock() that they can do the above logicals with next time or in > future(logical may changes some variables and those variables' change could > be see with latency). That looks like a Trylock() implemetion. >
One reason the TryLock method does not exist is that its behavior cannot be expressed without reference to some notion of goroutine identity. That is, its doc comment would read "succeeds immediately if the current goroutine already holds the lock". The designers of the language have strived to avoid making goroutine state relevant to the behavior of any function since it makes programs had to reason about and prevents programmers from freely moving work to a different goroutine. Another reason is described in Chapter 9 of our book (gopl.io): "There is a good reason Go’s mutexes are not re-entrant. The purpose of a mutex is to ensure that certain invariants of the shared variables are maintained at critical points during program execution. One of the invariants is “no goroutine is accessing the shared variables,” but there may be additional invariants specific to the data structures that the mutex guards. When a goroutine acquires a mutex lock, it may assume that the invariants hold. While it holds the lock, it may update the shared variables so that the invariants are temporarily violated. However, when it releases the lock, it must guarantee that order has been restored and the invariants hold once again. Although a re-entrant mutex would ensure that no other goroutines are accessing the shared variables, it cannot protect the additional invariants of those variables." -- 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. For more options, visit https://groups.google.com/d/optout.
