[Cuis-dev] Cuis web package

[Jaromir Matas]

Hi Andres,

Thanks! I correct myself, yes the circualr referenced objects in this 
case should be gc'd indeed.

However,
When you run you example and get to `w first`, the process hasn't run 
yet and is still waiting at the Processor's priority 40 list (see 
Processor waitingProcessesAt: 40) - so this is the reference at this 
point.

When the example finishes execution the UI lets your new process run and 
create the semaphore - becoming a zombie because the only (strong) 
references are circular now.

So, if I add a `yield` before the gc, the example works as expected:

w := WeakArray new: 1.
w at: 1 put: [Semaphore new wait] newProcess resume.
Processor yield.
Smalltalk garbageCollect.
w first

Does this explain the behavior you observed? Or am I still missing 
something?
best,
Jaromir


On 13-Jun-24 9:01:53 PM, "Andres Valloud via Cuis-dev" 
<cuis-dev at lists.cuis.st> wrote:

>Check this out.  In a workspace, put in the following code.
>
>w := WeakArray new: 1.
>w at: 1 put: [Semaphore new wait] newProcess resume.
>Smalltalk garbageCollect.
>w first
>
>If you evaluate it, you see that the weak array still references the zombie process.
>
>Now, somewhere else in the workspace, do a print-it of 2 + 3.  Then, run the last two lines of the first snippet.
>
>Smalltalk garbageCollect.
>w first
>
>And now the process is gone.  It appears that workspace do-its are remembering way more than they should.
>
>The fascinating thing is that the reference finder doesn't find the presumptive references (and class skipping is not the issue).  So, what's going on here?
>
>On 6/13/24 11:38 AM, Andres Valloud via Cuis-dev wrote:
>>>>So, where is the reference to this zombie process object?
>>>
>>>The process's myList references the new semaphore and the semaphore references the process back. So it won't go away unless the semaphore is signaled or the process terminated from another process (or from Process Browser, Inspector etc.) What do I miss?
>>
>>Why isn't this just a cycle of garbage objects?  Who is referencing the semaphore?
>>
>>In others Smalltalk systems, I know for a fact that when I tried this the zombie process and the semaphore were summarily scavenged away with extreme prejudice :p.
>>
>>Andres.
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