Re: [go-nuts] is this code thread safety?

[Drew Derbyshire]

What Jan said.  I had started my own post before I realize other sane 
people checked in about the absurd colors.

On Thursday, November 2, 2017 at 3:13:07 AM UTC-7, Jan Mercl wrote:
>
> On Thu, Nov 2, 2017 at 6:54 AM sheepbao  
> wrote:
>
> > the close function is thread safety? how about call `closed` at the same 
> time. 
>
> I don't know, but you might want to reconsider posting text with contrast 
> going in some places below 10% (guestimated), to possibly get answers from 
> people which refuse to read what's not really readable.
>
> Black on white is the best.
>
> -- 
>
> -j
>

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Re: [go-nuts] is this code thread safety?

['Bryan Mills' via golang-nuts]

In general you can use the race detector to help answer this sort of 
question, although it does not detect all races.

Unfortunately, it doesn't detect this one. (I've 
filed https://golang.org/issue/22569, because I think it should.)

On Friday, November 3, 2017 at 4:08:19 AM UTC-4, sheepbao wrote:
>
> Thanks, I got it.
>
> On Friday, November 3, 2017 at 11:26:31 AM UTC+8, Jesse McNelis wrote:
>>
>> On Thu, Nov 2, 2017 at 4:54 PM, sheepbao  wrote: 
>> > 
>> > the close function is thread safety? how about call `closed` at the 
>> same 
>> > time. 
>>
>> It's not safe. Multiple goroutines can enter the 'default'  case in 
>> that select and close() the channel multiple times. 
>>
>> "Sending to or closing a closed channel causes a run-time panic." 
>> https://golang.org/ref/spec#Close 
>>
>

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Re: [go-nuts] is this code thread safety?

[sheepbao]

Thanks, I got it.

On Friday, November 3, 2017 at 11:26:31 AM UTC+8, Jesse McNelis wrote:
>
> On Thu, Nov 2, 2017 at 4:54 PM, sheepbao  
> wrote: 
> > 
> > the close function is thread safety? how about call `closed` at the same 
> > time. 
>
> It's not safe. Multiple goroutines can enter the 'default'  case in 
> that select and close() the channel multiple times. 
>
> "Sending to or closing a closed channel causes a run-time panic." 
> https://golang.org/ref/spec#Close 
>

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Re: [go-nuts] is this code thread safety?

[Jesse McNelis]

On Thu, Nov 2, 2017 at 4:54 PM, sheepbao  wrote:
>
> the close function is thread safety? how about call `closed` at the same
> time.

It's not safe. Multiple goroutines can enter the 'default'  case in
that select and close() the channel multiple times.

"Sending to or closing a closed channel causes a run-time panic."
https://golang.org/ref/spec#Close

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[go-nuts] is this code thread safety?

[sheepbao]

package main

import "time"
import "fmt"
import "sync/atomic"

func main() {
   die := make(chan struct{})
   i := int32(0)
   closed := func() {
   select {
   case <-die:
   atomic.AddInt32(, 1)
   default:
   close(die)
   fmt.Println("closed")
   }
   }
   N := 10
   for i := 0; i < N; i++ {
   go closed()
   }
   time.Sleep(10 * time.Second)
   fmt.Println(atomic.LoadInt32())
}


the close function is thread safety? how about call `closed` at the same 
time.

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