On Thu, Nov 3, 2016 at 10:19 PM, 刘桂祥 <liuguixiang...@gmail.com> wrote:
> can you explain why whis ?
A map is basically a pointer to a complex data structure. Setting a
value in a map changes that data structure. If one goroutine is
reading from the data structure while a different goroutine is writing
to the data structure, the results are completely unpredictable. In
the worst case they could even cause the program to crash.
Ian
> 在 2016年11月4日星期五 UTC+8下午1:16:39，Ian Lance Taylor写道：
>>
>> On Thu, Nov 3, 2016 at 8:37 PM, 刘桂祥 <liuguix...@gmail.com> wrote:
>> > // example.go
>> >
>> > package main
>> >
>> > var gMap = make(map[int]int)
>> >
>> > func w() {
>> > temp := make(map[int]int)
>> > temp[1] = 100
>> > temp[2] = 200
>> > gMap = temp // Does the compiler or cpu will reorder temp[1]=100,
>> > temp[2]=200, gMap=temp ??
>> > }
>> >
>> > func r() {
>> > local := gMap
>> > println(local[1], local[2])
>> > }
>> >
>> > func main() {
>> >
>> > go w()
>> > go r()
>> >
>> > // ...
>> > }
>> >
>> > I have one goroutine to read the map and one goroutine to rewrite the
>> > global
>> > map variable does this safe ??
>>
>> No. Use a lock.
>>
>> 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+unsubscr...@googlegroups.com.
> For more options, visit https://groups.google.com/d/optout.
--
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.
