Hi Brian, thanks for replying! So you mean that I have to use 5 Mutexes for Market data of each one source ? That is exactly what I want to do. Every action of RW marketMap[i] must comes in one line, but RW marketMap[j] concurrently is allowed. And mapLocks now is fine in golang?
The reason why I do not use channel is that not each one market updates is needed, but I need to take samples from time to time. On Wed, Feb 23, 2022 at 6:06 PM Brian Candler <b.cand...@pobox.com> wrote: > On Wednesday, 23 February 2022 at 08:49:26 UTC yan.z...@gmail.com wrote: > >> I have heard that sync.Map allows for reading simultaneously among >> multiple goroutines. >> > > It does. But it doesn't synchronize what you do with the values returned > from the map. So if you retrieve a *copy* of a value, or replace the > value, it's fine. But if you retrieve a pointer, and then either read via > that pointer or update the object via that pointer, you'll be back to a > race condition. You should note that various Go data types include > pointers internally, especially slices. However in your case, you're > proposing that a sync.Map (safe) contains pointers to *Market data (unsafe > to access concurrently). So you would still need a mutex to protect each > Market object, and every read and write would have to apply that mutex. > > Personally, I would avoid locks and use channels instead. It's much > easier to reason about. Have one goroutine per market, and have it accept > 'update' and 'read' messages over a channel (or two different channels). > > -- > You received this message because you are subscribed to a topic in the > Google Groups "golang-nuts" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/golang-nuts/6I_kS6Pya0M/unsubscribe. > To unsubscribe from this group and all its topics, 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/1f5beaae-e5d0-4e13-bbe1-28d28ee47e9dn%40googlegroups.com > <https://groups.google.com/d/msgid/golang-nuts/1f5beaae-e5d0-4e13-bbe1-28d28ee47e9dn%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- 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/CADEX6_VXBtWuVCKCZziejjhEf8PWmEjzQhmW4NyAZkXdqJGWJw%40mail.gmail.com.
