Re: [Pharo-users] Threads safety in Pharo

[Alidra Abdelghani via Pharo-users]

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Thanks Guille for your answer,
From what I understand, it is mainly a synchronisation problem. Why cant' 
existing synchronisation mechanisms (semaphores and mutex) be used?
Abdelghani


> On 31 Jul 2017, at 18:44, Guillermo Polito <guillermopol...@gmail.com> wrote:
> 
> I believe there is no such a document. It would be however interesting to 
> investigate it a bit deeper. In general, the problem we talk about when we 
> talk about thread safety is the following: Can we run a workspace in a 
> separate thread than a browser and provide correct results? Can we run two 
> browsers concurrently and change code from both of them?
> 
> The thread safety problem has several levels I'd say:
> 
>  - the kernel of the language (classes, methods, compilation, and so on) 
> cannot safely be modified while other threads are running. Thus, if we 
> compile a new version of a method in a thread, that could break a separate 
> thread that was using that method.
> 
>  - there are several libraries using global state. We should investigate if 
> they work correctly when using them concurrently.
>     E.g., source code management is not thread safe. This could cause a 
> source code corruption if several methods are modified concurrently.
>     Like that, we sh n ould investigate all libraries and see what should be 
> adapted and if there is a need at all.
> 
>  - in a third level, general core libraries (collections, networking, files, 
> etc) are not designed to be thread safe and that is natural. For example, 
> most of the time you don't want that your collection is accessed 
> concurrently. For such cases, some libraries could provide some 
> extensions/wrappers/whatsoever to provide some synchronization mechanism. 
> Otherwise it is the responsibility of the user to synchronize usages with 
> semaphores/mutexes.
>  
> 
> On Mon, Jul 31, 2017 at 1:38 AM, Alidra Abdelghani via Pharo-users 
> <pharo-users@lists.pharo.org <mailto:pharo-users@lists.pharo.org>> wrote:
> 
> 
> ---------- Forwarded message ----------
> From: Alidra Abdelghani <alidran...@yahoo.fr <mailto:alidran...@yahoo.fr>>
> To: pharo-users@lists.pharo.org <mailto:pharo-users@lists.pharo.org>
> Cc: "Stéphane Ducasse" <stephane.duca...@inria.fr 
> <mailto:stephane.duca...@inria.fr>>, farid arfi <arf...@hotmail.com 
> <mailto:arf...@hotmail.com>>
> Bcc: 
> Date: Mon, 31 Jul 2017 01:38:58 +0200
> Subject: Threads safety in Pharo
> Hi,
> 
> Somebody once evoked the problem of threads safety in Pharo. With a friend of 
> mine who is expert in formal methods and process scheduling, we would like to 
> have a look on it.
> Does anyone knows a good document describing the problem of Pharo with 
> threads safety or at least any document that we can start with?
> 
> Thanks in advance,
> Abdelghani
> 
> 
> 
> 
> 
> 
> -- 
>    
> Guille Polito
> 
> Research Engineer
> French National Center for Scientific Research - http://www.cnrs.fr 
> <http://www.cnrs.fr/>
> 
> 
> Web: http://guillep.github.io <http://guillep.github.io/>
> Phone: +33 06 52 70 66 13

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