[swift-users] Swift 4.0 bug in concurrent array access

[Jordan Rose]

That sounds expected to me. While Array values are thread-safe, writing to the global variable 'array' from two different threads would be a race. You can see this properly diagnosed if you enable Thread Sanitizer.

Jordan

P.S. bugs.swift.org should be back up now, if you find any other issues.


> On Jan 8, 2018, at 11:02, ⁨‫Fadi Botros‬ ‫ via swift-users⁩ <⁨swift-users at swift.org⁩> wrote:
> 
> I'm on macOS Sierra 10.12.6, and using Swift 4.0
> Tried to access the array concurrently to see whether is it synchronized or no
> import Foundation let global = DispatchQueue.global() var array: [Int] = [ - Pastebin.com <https://pastebin.com/PnvyM3Qn>
> 
> 
> import Foundation let global = DispatchQueue.global() var array: [Int...
>  <https://pastebin.com/PnvyM3Qn>
> 
> When tried to run it using the terminal
> This crash happened
> 
> swift(69836,0x700002dc2000) malloc: *** error for object 0x7ffe4be237e0: pointer - Pastebin.com <https://pastebin.com/vrdKTfrP>
> 
> 
> swift(69836,0x700002dc2000) malloc: *** error for object 0x7ffe4be237e0: po...
>  <https://pastebin.com/vrdKTfrP>
> 
> Avoided this crash using Serial Dispatch Queue
> 
> let otherDispatch = DispatchQueue(label: "another.dispatch.com",
>                                   qos: .default)
> func appending(_ i: Int) {
>   otherDispatch.sync { array.append(i) }
> }
> 
> 
> 
> Also tried to file this issue on bugs.swift.org, and it appears your site is down (under maintainence)
> 
> Sorry
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