On Wednesday, March 22, 2017 at 7:49:39 PM UTC+8, Dave Cheney wrote:
>
> Well, that program isn't that simple because of the closure, but also
> because it contains a data race
>
> Something like this is easier to reason about
>
> var x *int
>
> func main() {
> var a int
> x = &a
> fmt.Println(*x)
> }
>
or like this, :D
package main
func f(*int){
var b int
// avoid f to be inlined.
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
b++
}
func main() {
var a int
f(&a) // &a escapes to heap
}
>
> On Wednesday, 22 March 2017 21:59:17 UTC+11, T L wrote:
>>
>>
>>
>> On Wednesday, March 22, 2017 at 6:40:53 PM UTC+8, Jesse McNelis wrote:
>>>
>>> On Wed, Mar 22, 2017 at 8:51 PM, T L <[email protected]> wrote:
>>> >
>>> > More accurately, I think it should be: from the POV of a programmer,
>>> it's
>>> > globals, and things reachable from each goroutine.
>>> >
>>>
>>> The only way to reach a value is through a variable in scope and the
>>> only variables in scope are global or on the stack.
>>>
>>> 'heap pointers of local allocated memory blocks' are stored where ever
>>> you put them, but you can only put them in places you can find by
>>> using global or local stack variables.
>>>
>>
>> So for this simple program:
>>
>> func main() {
>> var a int
>> go func() { // new goroutine
>> a++
>> }()
>>
>> // ...
>> }
>>
>> a will be allocated on heap.
>> a is referenced by both stack of main and the new goroutine?
>> how is it referenced, the pointer of a's memory block is stored in both
>> stacks?
>>
>
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