[Pharo-project] 12186 image quit problem

Igor Stasenko siguctua at gmail.com
Sun Oct 10 12:46:50 EDT 2010


On 10 October 2010 17:40, Schwab,Wilhelm K <bschwab at anest.ufl.edu> wrote:
> Sig,
>
> Have you thought about using a Mutex?  Maybe I'm missing something in life, but long ago I decided the #forMutualExclusion is *beyond* private.  Semaphores are wonderful for #wait/#signal.  But for #critical:, I use Mutex which won't deadlock a thread with itself.
>

yes,  i thought about it. It wont help in this situation,
because if you start modifying dictionary inside a loop, which
scanning its elements (like #do:)
you'll have very unpleasant results.

All HostSystemMenusProxy doing during #finalize is removing itself
from weakregistry (which is complete nonsense, since weak registry
cleaning itself from dead stuff anyways).
So,
 self protected: [
        valueDictionary expiredValuesDo: [:finItem |
                finItem finalizeValues  ].
  ].

actually triggers a bug/mistake in HostSystemMenusProxy , which leads
to deadlock.
:)

> Bill
>
>
> ________________________________________
> From: pharo-project-bounces at lists.gforge.inria.fr [pharo-project-bounces at lists.gforge.inria.fr] On Behalf Of Igor Stasenko [siguctua at gmail.com]
> Sent: Sunday, October 10, 2010 7:56 AM
> To: Pharo-project at lists.gforge.inria.fr
> Subject: Re: [Pharo-project] 12186 image quit problem
>
> OKay, now i see what the problem:
>
> <weak registry protected>
>   <finalize items>
>       <HostSystemMenusProxy>>finalize>
>            ....
>            <HostSystemMenusProxy class>>unregister>
>              <weak registry protected>
>
>
> In my WeakRegistry, a #finalize message sent while registry semaphore locked,
> so, in case if object in #finalize trying to manipulate with registry
> then it going to deadlock.
>
> Then following piece:
>
> WeakRegistry>>finalizeValues
>
> self protected: [
>        valueDictionary expiredValuesDo: [:finItem |
>                finItem finalizeValues  ].
>  ].
>
> should be rewritten as:
>
> | expired |
> expired := OrderedCollection new.
> self protected: [
>        valueDictionary expiredValuesDo: [:finItem | expired add: finItem ]
>  ].
> expired do: #finalizeValues.
>
>
> But either way, HostSystemMenusProxy should not attempt remove itself
> from registry during #finalize (and causing a deadlock),
> since its pointless.
>
>
> --
> Best regards,
> Igor Stasenko AKA sig.
>
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-- 
Best regards,
Igor Stasenko AKA sig.




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