Re: [Pharo-users] Thread-safe initialization of class state (was Re: Threads safety in Pharo)

[Tim Mackinnon]

I think that thread safety comes with a penalty - so the overarching question 
is are we trying to create thread safe browsers (or does a thread safe penalty 
even impact browsing as maybe it's negligible?)

Monty - maybe you could measure the impact if you are interested in this? If 
it's not much and we just need to encapsulate it with some mechanism 
(potentially having thread safety critics we can enable) then it's possibly 
something Calypso can embrace.

This said, multi user editing is not something that has really taken off. Jason 
at VW did lots with Wolfpack, and it wasn't an idea that gained lots of 
traction a few years ago (sadly).

It's tricky as we have to spend our engineering resources wisely.

Tim

Sent from my iPhone

> On 11 Aug 2017, at 19:41, Gabriel Cotelli <g.cote...@gmail.com> wrote:
> 
> Suerly we can add a Critics Rule trying to detect the invalid pattern.
> 
>> On Fri, Aug 11, 2017 at 10:39 AM, monty <mon...@programmer.net> wrote:
>> > Sent: Friday, August 11, 2017 at 6:36 AM
>> > From: "Denis Kudriashov" <dionisi...@gmail.com>
>> > To: "Any question about pharo is welcome" <pharo-users@lists.pharo.org>
>> > Subject: Re: [Pharo-users] Thread-safe initialization of class state (was 
>> > Re: Threads safety in Pharo)
>> >
>> > What package you explore? I not find fileTypes method in Pharo 7.
>> 
>> Like I said, it's a hypothetical example. But I'm sure you could find 
>> similar examples of unsafe class state initialization in the image and in 
>> popular libraries.
>> 
>> > 2017-08-11 8:53 GMT+02:00 monty 
>> > <mon...@programmer.net[mailto:mon...@programmer.net]>:Here's a 
>> > hypothetical broken class method that does lazy initialization of a class 
>> > inst var:
>> >
>> > fileTypes
>> > fileTypes ifNil: [
>> > fileTypes := Dictionary new.
>> > fileTypes
>> > at: 'txt' put: 'Text File';
>> > at: 'html' put: 'Web Page';
>> > at: 'pdf' put: 'Portable Document Format File';
>> > at: 'doc' put: 'Microsoft Word Document'].
>> > ^ fileTypes.
>> >
>> > Because the assignment is done first and the initialization is done after 
>> > with a cascade of interruptable sends of #at:put:, there's a window after 
>> > the assignment where 'fileTypes' is not nil but also not fully 
>> > initialized--a race condition.
>> >
>> > The fix is simple. Do the initialization before the atomic assignment 
>> > takes place, so the var is only ever bound to nil or a fully initialized 
>> > object:
>> >
>> > fileTypes
>> > fileTypes ifNil: [
>> > fileTypes :=
>> > Dictionary new
>> > at: 'txt' put: 'Text File';
>> > at: 'html' put: 'Web Page';
>> > at: 'pdf' put: 'Portable Document Format 
>> > File';
>> > at: 'doc' put: 'Microsoft Word Document';
>> > yourself].
>> > ^ fileTypes.
>> >
>> > The fixed code is still vulnerable to duplicate initialization, because 
>> > the initialization sequence is interruptable and 'fileTypes' is nil during 
>> > it, but as long as the initialization is cheap enough, has no side effects 
>> > that restrict how often it can be done, and it's enough that the 
>> > initialized objects are equal (but not identical), that's OK.
>> >
>> > If it's too complex for a single statement, you can use a temp vars or put 
>> > it in a separate factory method:
>> >
>> > fileTypes
>> > fileTypes ifNil: [
>> > fileTypes := self newFileTypes].
>> > ^ fileTypes.
>> >
>> > Similar precautions (given how easy) might as well be taken with explicit 
>> > initialization of class state too. Of course if the object is mutated 
>> > later (in other methods), then Mutexes or other constructs are needed to 
>> > guard access. But for immutable class state, ensuring initialization is 
>> > done before assignment should be enough.
>> >
>> > > Sent: Tuesday, August 01, 2017 at 7:36 AM
>> > > From: "Stephane Ducasse" 
>> > > <stepharo.s...@gmail.com[mailto:stepharo.s...@gmail.com]>
>> > > To

Re: [Pharo-users] Thread-safe initialization of class state (was Re: Threads safety in Pharo)

[Gabriel Cotelli]

Suerly we can add a Critics Rule trying to detect the invalid pattern.

On Fri, Aug 11, 2017 at 10:39 AM, monty <mon...@programmer.net> wrote:

> > Sent: Friday, August 11, 2017 at 6:36 AM
> > From: "Denis Kudriashov" <dionisi...@gmail.com>
> > To: "Any question about pharo is welcome" <pharo-users@lists.pharo.org>
> > Subject: Re: [Pharo-users] Thread-safe initialization of class state
> (was Re: Threads safety in Pharo)
> >
> > What package you explore? I not find fileTypes method in Pharo 7.
>
> Like I said, it's a hypothetical example. But I'm sure you could find
> similar examples of unsafe class state initialization in the image and in
> popular libraries.
>
> > 2017-08-11 8:53 GMT+02:00 monty <mon...@programmer.net[mailto:
> mon...@programmer.net]>:Here's a hypothetical broken class method that
> does lazy initialization of a class inst var:
> >
> > fileTypes
> > fileTypes ifNil: [
> > fileTypes := Dictionary new.
> > fileTypes
> > at: 'txt' put: 'Text File';
> > at: 'html' put: 'Web Page';
> > at: 'pdf' put: 'Portable Document Format File';
> > at: 'doc' put: 'Microsoft Word Document'].
> > ^ fileTypes.
> >
> > Because the assignment is done first and the initialization is done
> after with a cascade of interruptable sends of #at:put:, there's a window
> after the assignment where 'fileTypes' is not nil but also not fully
> initialized--a race condition.
> >
> > The fix is simple. Do the initialization before the atomic assignment
> takes place, so the var is only ever bound to nil or a fully initialized
> object:
> >
> > fileTypes
> > fileTypes ifNil: [
> > fileTypes :=
> > Dictionary new
> > at: 'txt' put: 'Text File';
> > at: 'html' put: 'Web Page';
> > at: 'pdf' put: 'Portable Document Format
> File';
> > at: 'doc' put: 'Microsoft Word Document';
> > yourself].
> > ^ fileTypes.
> >
> > The fixed code is still vulnerable to duplicate initialization, because
> the initialization sequence is interruptable and 'fileTypes' is nil during
> it, but as long as the initialization is cheap enough, has no side effects
> that restrict how often it can be done, and it's enough that the
> initialized objects are equal (but not identical), that's OK.
> >
> > If it's too complex for a single statement, you can use a temp vars or
> put it in a separate factory method:
> >
> > fileTypes
> > fileTypes ifNil: [
> > fileTypes := self newFileTypes].
> > ^ fileTypes.
> >
> > Similar precautions (given how easy) might as well be taken with
> explicit initialization of class state too. Of course if the object is
> mutated later (in other methods), then Mutexes or other constructs are
> needed to guard access. But for immutable class state, ensuring
> initialization is done before assignment should be enough.
> >
> > > Sent: Tuesday, August 01, 2017 at 7:36 AM
> > > From: "Stephane Ducasse" <stepharo.s...@gmail.com[mailto:
> stepharo.s...@gmail.com]>
> > > To: "Any question about pharo is welcome" <pharo-users@lists.pharo.org
> [mailto:pharo-users@lists.pharo.org]>
> > > Subject: Re: [Pharo-users] Threads safety in Pharo
> > >
> > > I would love to have an analysis of assumptions made in some code.
> > > Because my impression is that the concurrent code is sometimes defined
> > > knowing the underlying logic of scheduler and this is not good.
> > > As I said to abdel privately in french it would be great to start from
> > > my french squeak book (Yes I wrote one long time ago) chapter on
> > > concurrent programming and turn it into a pharo chapter.
> > >
> > > Stef
> > >
> > > On Tue, Aug 1, 2017 at 1:31 PM, Ben Coman <b...@openinworld.com[mailto:
> b...@openinworld.com]> wrote:
> > > > Not sure I'll have what you're looking for, but to start, do you mean
> > > > Pharo's green threads or vm native threads?
> > > > cheers -ben
> > > >
> > > > On Mon, Jul 31, 2017 at 7:38 AM, Alidra Abdelghani via Pharo-users
> > > > <pharo-users@lists.pharo.org[mailto:pharo-users@lists.pharo.org]>
> wrote:
> > > &

Re: [Pharo-users] Thread-safe initialization of class state (was Re: Threads safety in Pharo)

[monty]

> Sent: Friday, August 11, 2017 at 6:36 AM
> From: "Denis Kudriashov" <dionisi...@gmail.com>
> To: "Any question about pharo is welcome" <pharo-users@lists.pharo.org>
> Subject: Re: [Pharo-users] Thread-safe initialization of class state (was Re: 
> Threads safety in Pharo)
> 
> What package you explore? I not find fileTypes method in Pharo 7. 

Like I said, it's a hypothetical example. But I'm sure you could find similar 
examples of unsafe class state initialization in the image and in popular 
libraries.

> 2017-08-11 8:53 GMT+02:00 monty 
> <mon...@programmer.net[mailto:mon...@programmer.net]>:Here's a hypothetical 
> broken class method that does lazy initialization of a class inst var:
> 
> fileTypes
> fileTypes ifNil: [
> fileTypes := Dictionary new.
> fileTypes
> at: 'txt' put: 'Text File';
> at: 'html' put: 'Web Page';
> at: 'pdf' put: 'Portable Document Format File';
> at: 'doc' put: 'Microsoft Word Document'].
> ^ fileTypes.
> 
> Because the assignment is done first and the initialization is done after 
> with a cascade of interruptable sends of #at:put:, there's a window after the 
> assignment where 'fileTypes' is not nil but also not fully initialized--a 
> race condition.
> 
> The fix is simple. Do the initialization before the atomic assignment takes 
> place, so the var is only ever bound to nil or a fully initialized object:
> 
> fileTypes
> fileTypes ifNil: [
> fileTypes :=
> Dictionary new
> at: 'txt' put: 'Text File';
> at: 'html' put: 'Web Page';
> at: 'pdf' put: 'Portable Document Format 
> File';
> at: 'doc' put: 'Microsoft Word Document';
> yourself].
> ^ fileTypes.
> 
> The fixed code is still vulnerable to duplicate initialization, because the 
> initialization sequence is interruptable and 'fileTypes' is nil during it, 
> but as long as the initialization is cheap enough, has no side effects that 
> restrict how often it can be done, and it's enough that the initialized 
> objects are equal (but not identical), that's OK.
> 
> If it's too complex for a single statement, you can use a temp vars or put it 
> in a separate factory method:
> 
> fileTypes
> fileTypes ifNil: [
> fileTypes := self newFileTypes].
> ^ fileTypes.
> 
> Similar precautions (given how easy) might as well be taken with explicit 
> initialization of class state too. Of course if the object is mutated later 
> (in other methods), then Mutexes or other constructs are needed to guard 
> access. But for immutable class state, ensuring initialization is done before 
> assignment should be enough.
> 
> > Sent: Tuesday, August 01, 2017 at 7:36 AM
> > From: "Stephane Ducasse" 
> > <stepharo.s...@gmail.com[mailto:stepharo.s...@gmail.com]>
> > To: "Any question about pharo is welcome" 
> > <pharo-users@lists.pharo.org[mailto:pharo-users@lists.pharo.org]>
> > Subject: Re: [Pharo-users] Threads safety in Pharo
> >
> > I would love to have an analysis of assumptions made in some code.
> > Because my impression is that the concurrent code is sometimes defined
> > knowing the underlying logic of scheduler and this is not good.
> > As I said to abdel privately in french it would be great to start from
> > my french squeak book (Yes I wrote one long time ago) chapter on
> > concurrent programming and turn it into a pharo chapter.
> >
> > Stef
> >
> > On Tue, Aug 1, 2017 at 1:31 PM, Ben Coman 
> > <b...@openinworld.com[mailto:b...@openinworld.com]> wrote:
> > > Not sure I'll have what you're looking for, but to start, do you mean
> > > Pharo's green threads or vm native threads?
> > > cheers -ben
> > >
> > > On Mon, Jul 31, 2017 at 7:38 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
> >

Re: [Pharo-users] Thread-safe initialization of class state (was Re: Threads safety in Pharo)

[monty]

> Sent: Friday, August 11, 2017 at 5:51 AM
> From: "Tim Mackinnon" <tim@testit.works>
> To: "Any question about pharo is welcome" <pharo-users@lists.pharo.org>
> Subject: Re: [Pharo-users] Thread-safe initialization of class state (was Re: 
> Threads safety in Pharo)
> 
> Interesting, your example was subtle enough that I had to read it a few times 
> to understand the issue. (I was caught up on the ifNil and not the contents).

That's the problem. They're close enough that someone could mistakenly refactor 
the correct code into the incorrect code--and that code would be perfectly fine 
for lazy initialization of instance state in a non-concurrent class. That's why 
I always insert a small comment before explaining why it was written that way.
 
> Actually, thinking about it - isn't the real issue the #ifNil - you want an 
> atomic version.
>  
> It strikes me you could wrap the whole concept into something like an 
> AtomicLazyVariable? E.g.
>  
> initialise
>fileTypes := AtomicLazyVariable using: [
> 
>Dictionary new
>at: 'txt' put: 'Text File';
>at: 'html' put: 'Web Page';
>yourself ].
>  
> Then have something
>  
> fileTypes 
>  ^fileTypes value
>  
> Where you have a critical section in #value?
>  
> Tim
>  
> Sent from my iPhone
> On 11 Aug 2017, at 07:53, monty 
> <mon...@programmer.net[mailto:mon...@programmer.net]> wrote:
>  
> Here's a hypothetical broken class method that does lazy initialization of a 
> class inst var:
> 
> fileTypes
>fileTypes ifNil: [
>fileTypes := Dictionary new.
>fileTypes
>at: 'txt' put: 'Text File';
>at: 'html' put: 'Web Page';
>at: 'pdf' put: 'Portable Document Format File';
>at: 'doc' put: 'Microsoft Word Document'].
>^ fileTypes.
> 
> Because the assignment is done first and the initialization is done after 
> with a cascade of interruptable sends of #at:put:, there's a window after the 
> assignment where 'fileTypes' is not nil but also not fully initialized--a 
> race condition.
> 
> The fix is simple. Do the initialization before the atomic assignment takes 
> place, so the var is only ever bound to nil or a fully initialized object:
> 
> fileTypes
>fileTypes ifNil: [
>fileTypes :=
>Dictionary new
>at: 'txt' put: 'Text File';
>at: 'html' put: 'Web Page';
>at: 'pdf' put: 'Portable Document Format File';
>at: 'doc' put: 'Microsoft Word Document';
>yourself].
>^ fileTypes.
> 
> The fixed code is still vulnerable to duplicate initialization, because the 
> initialization sequence is interruptable and 'fileTypes' is nil during it, 
> but as long as the initialization is cheap enough, has no side effects that 
> restrict how often it can be done, and it's enough that the initialized 
> objects are equal (but not identical), that's OK.
> 
> If it's too complex for a single statement, you can use a temp vars or put it 
> in a separate factory method:
> 
> fileTypes
>fileTypes ifNil: [
>fileTypes := self newFileTypes].
>^ fileTypes.
> 
> Similar precautions (given how easy) might as well be taken with explicit 
> initialization of class state too. Of course if the object is mutated later 
> (in other methods), then Mutexes or other constructs are needed to guard 
> access. But for immutable class state, ensuring initialization is done before 
> assignment should be enough.
>  Sent: Tuesday, August 01, 2017 at 7:36 AMFrom: "Stephane Ducasse" 
> <stepharo.s...@gmail.com[mailto:stepharo.s...@gmail.com]>To: "Any question 
> about pharo is welcome" 
> <pharo-users@lists.pharo.org[mailto:pharo-users@lists.pharo.org]>Subject: Re: 
> [Pharo-users] Threads safety in Pharo I would love to have an analysis of 
> assumptions made in some code.Because my impression is that the concurrent 
> code is sometimes definedknowing the underlying logic of scheduler and this 
> is not good.As I said to abdel privately in french it would be great to start 
> frommy french squeak book (Yes I wrote one long time ago) chapter 
> onconcurrent programming and turn it into a pharo chapter. Stef On Tue, Aug 
> 1, 2017 at 1:31 PM, Ben Coman 
> <b...@openinworld.com[mailto:b...@openinworld.com]> wrote:Not sure I'll have 
> what you're looking for, but to start, do you meanPharo's green threads or vm 
> native threads?cheers -ben On Mon, Jul 31, 2017 at 7:38 AM, Alidra Abdelghani 
> via 
> Pharo-users<pharo-users@lists.pharo.org[mailto:pharo-users@lists.pharo.org]> 
> wro

Re: [Pharo-users] Thread-safe initialization of class state (was Re: Threads safety in Pharo)

[Denis Kudriashov]

What package you explore? I not find fileTypes method in Pharo 7.

2017-08-11 8:53 GMT+02:00 monty :

> Here's a hypothetical broken class method that does lazy initialization of
> a class inst var:
>
> fileTypes
> fileTypes ifNil: [
> fileTypes := Dictionary new.
> fileTypes
> at: 'txt' put: 'Text File';
> at: 'html' put: 'Web Page';
> at: 'pdf' put: 'Portable Document Format File';
> at: 'doc' put: 'Microsoft Word Document'].
> ^ fileTypes.
>
> Because the assignment is done first and the initialization is done after
> with a cascade of interruptable sends of #at:put:, there's a window after
> the assignment where 'fileTypes' is not nil but also not fully
> initialized--a race condition.
>
> The fix is simple. Do the initialization before the atomic assignment
> takes place, so the var is only ever bound to nil or a fully initialized
> object:
>
> fileTypes
> fileTypes ifNil: [
> fileTypes :=
> Dictionary new
> at: 'txt' put: 'Text File';
> at: 'html' put: 'Web Page';
> at: 'pdf' put: 'Portable Document Format
> File';
> at: 'doc' put: 'Microsoft Word Document';
> yourself].
> ^ fileTypes.
>
> The fixed code is still vulnerable to duplicate initialization, because
> the initialization sequence is interruptable and 'fileTypes' is nil during
> it, but as long as the initialization is cheap enough, has no side effects
> that restrict how often it can be done, and it's enough that the
> initialized objects are equal (but not identical), that's OK.
>
> If it's too complex for a single statement, you can use a temp vars or put
> it in a separate factory method:
>
> fileTypes
> fileTypes ifNil: [
> fileTypes := self newFileTypes].
> ^ fileTypes.
>
> Similar precautions (given how easy) might as well be taken with explicit
> initialization of class state too. Of course if the object is mutated later
> (in other methods), then Mutexes or other constructs are needed to guard
> access. But for immutable class state, ensuring initialization is done
> before assignment should be enough.
>
> > Sent: Tuesday, August 01, 2017 at 7:36 AM
> > From: "Stephane Ducasse" 
> > To: "Any question about pharo is welcome" 
> > Subject: Re: [Pharo-users] Threads safety in Pharo
> >
> > I would love to have an analysis of assumptions made in some code.
> > Because my impression is that the concurrent code is sometimes defined
> > knowing the underlying logic of scheduler and this is not good.
> > As I said to abdel privately in french it would be great to start from
> > my french squeak book (Yes I wrote one long time ago) chapter on
> > concurrent programming and turn it into a pharo chapter.
> >
> > Stef
> >
> > On Tue, Aug 1, 2017 at 1:31 PM, Ben Coman  wrote:
> > > Not sure I'll have what you're looking for, but to start, do you mean
> > > Pharo's green threads or vm native threads?
> > > cheers -ben
> > >
> > > On Mon, Jul 31, 2017 at 7:38 AM, Alidra Abdelghani via Pharo-users
> > >  wrote:
> > >>
> > >>
> > >>
> > >> -- Forwarded message --
> > >> From: Alidra Abdelghani 
> > >> To: pharo-users@lists.pharo.org
> > >> Cc: "Stéphane Ducasse" , farid arfi
> > >> 
> > >> 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
> > >>
> > >>
> > >>
> > >
> >
>
>

Re: [Pharo-users] Thread-safe initialization of class state (was Re: Threads safety in Pharo)

[Tim Mackinnon]

Interesting, your example was subtle enough that I had to read it a few times 
to understand the issue. (I was caught up on the ifNil and not the contents).

Actually, thinking about it - isn't the real issue the #ifNil - you want an 
atomic version.

It strikes me you could wrap the whole concept into something like an 
AtomicLazyVariable? E.g.

initialise
   fileTypes := AtomicLazyVariable using: [
   Dictionary new
   at: 'txt' put: 'Text File';
   at: 'html' put: 'Web Page';
   yourself ].

Then have something

fileTypes 
 ^fileTypes value

Where you have a critical section in #value?

Tim

Sent from my iPhone

> On 11 Aug 2017, at 07:53, monty  wrote:
> 
> Here's a hypothetical broken class method that does lazy initialization of a 
> class inst var:
> 
> fileTypes
>fileTypes ifNil: [
>fileTypes := Dictionary new.
>fileTypes
>at: 'txt' put: 'Text File';
>at: 'html' put: 'Web Page';
>at: 'pdf' put: 'Portable Document Format File';
>at: 'doc' put: 'Microsoft Word Document'].
>^ fileTypes.
> 
> Because the assignment is done first and the initialization is done after 
> with a cascade of interruptable sends of #at:put:, there's a window after the 
> assignment where 'fileTypes' is not nil but also not fully initialized--a 
> race condition.
> 
> The fix is simple. Do the initialization before the atomic assignment takes 
> place, so the var is only ever bound to nil or a fully initialized object:
> 
> fileTypes
>fileTypes ifNil: [
>fileTypes :=
>Dictionary new
>at: 'txt' put: 'Text File';
>at: 'html' put: 'Web Page';
>at: 'pdf' put: 'Portable Document Format File';
>at: 'doc' put: 'Microsoft Word Document';
>yourself].
>^ fileTypes.
> 
> The fixed code is still vulnerable to duplicate initialization, because the 
> initialization sequence is interruptable and 'fileTypes' is nil during it, 
> but as long as the initialization is cheap enough, has no side effects that 
> restrict how often it can be done, and it's enough that the initialized 
> objects are equal (but not identical), that's OK.
> 
> If it's too complex for a single statement, you can use a temp vars or put it 
> in a separate factory method:
> 
> fileTypes
>fileTypes ifNil: [
>fileTypes := self newFileTypes].
>^ fileTypes.
> 
> Similar precautions (given how easy) might as well be taken with explicit 
> initialization of class state too. Of course if the object is mutated later 
> (in other methods), then Mutexes or other constructs are needed to guard 
> access. But for immutable class state, ensuring initialization is done before 
> assignment should be enough.
> 
>> Sent: Tuesday, August 01, 2017 at 7:36 AM
>> From: "Stephane Ducasse" 
>> To: "Any question about pharo is welcome" 
>> Subject: Re: [Pharo-users] Threads safety in Pharo
>> 
>> I would love to have an analysis of assumptions made in some code.
>> Because my impression is that the concurrent code is sometimes defined
>> knowing the underlying logic of scheduler and this is not good.
>> As I said to abdel privately in french it would be great to start from
>> my french squeak book (Yes I wrote one long time ago) chapter on
>> concurrent programming and turn it into a pharo chapter.
>> 
>> Stef
>> 
>>> On Tue, Aug 1, 2017 at 1:31 PM, Ben Coman  wrote:
>>> Not sure I'll have what you're looking for, but to start, do you mean
>>> Pharo's green threads or vm native threads?
>>> cheers -ben
>>> 
>>> On Mon, Jul 31, 2017 at 7:38 AM, Alidra Abdelghani via Pharo-users
>>>  wrote:
 
 
 
 -- Forwarded message --
 From: Alidra Abdelghani 
 To: pharo-users@lists.pharo.org
 Cc: "Stéphane Ducasse" , farid arfi
 
 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
 
 
 
>>> 
>> 
>