[M3devel] WeakRef mechanism alive and well? cm3-cvshead

[Tony Hosking]

They should get unlinked from the global ring.

Antony Hosking | Associate Professor | Computer Science | Purdue  
University
305 N. University Street | West Lafayette | IN 47907 | USA
Office +1 765 494 6001 | Mobile +1 765 427 5484



On Mar 13, 2008, at 6:16 AM, Dragiša Durić wrote:

> What happens to thread stacks once threads are Join-ed?
>
> dd
>
> On Wed, 2008-03-12 at 11:12 -0400, Tony Hosking wrote:
>> This is probably a result of conservatism for references from thread
>> stacks which results in spurious retention.  It may be necessary to  
>> be
>> more careful about what references are held on the stack in the
>> threads implementation (and elsewhere in your code).  Until we
>> diagnose the place where objects are being retained it will be hard  
>> to
>> pinpoint.  You should realize that weak refs are a problem in many
>> language implementations, not just Modula-3.  I look forward to
>> hearing more definitively from you.
>>
>> Antony Hosking | Associate Professor | Computer Science | Purdue
>> University
>> 305 N. University Street | West Lafayette | IN 47907 | USA
>> Office +1 765 494 6001 | Mobile +1 765 427 5484
>>
>>
>>
>>
>>
>> On Mar 12, 2008, at 4:21 AM, Dragiša Durić wrote:
>>
>>> Problem in my case can be thoroughness of GC... Because it's linked
>>> list of WeakRef-ed objects, it's always first element in list to
>>> become
>>> unreachable first - all others are reachable at least through
>>> previous
>>> (in list) WeakRef-ed object. So, behaviour I have observed can be
>>> because of some thousands of freeable objects, that one is missed
>>> too
>>> often.
>>>
>>> I have other object being cleaned and counted... There also cleanup
>>> invocation looks like it's lagging too much. I'll come with numbers
>>> after I have more tests.
>>>
>>> dd
>>>
>>> On Tue, 2008-03-11 at 09:50 -0400, Tony Hosking wrote:
>>>> Sounds like we need some sort of testcase.  Would you be able to
>>>> devise one?  It will be hard to make it deterministic, but at
>>>> least we
>>>> should see a non-zero cleanup count.
>>>>
>>>> Antony Hosking | Associate Professor | Computer Science | Purdue
>>>> University
>>>> 305 N. University Street | West Lafayette | IN 47907 | USA
>>>> Office +1 765 494 6001 | Mobile +1 765 427 5484
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Mar 11, 2008, at 4:03 AM, Dragiša Durić wrote:
>>>>
>>>>> I have single linked list that I use to send messages to many
>>>>> threads.
>>>>> It's end is locked for addition, and current end is given to
>>>>> each
>>>>> new
>>>>> client connecting. This way, all client are going towards end of
>>>>> the
>>>>> list so it's head becomes unreferenced and goes away by GC.
>>>>>
>>>>> Except it does not.
>>>>>
>>>>> I've added WeakRef cleanup and sequential id's so I can record
>>>>> maximum
>>>>> freed id for checking. No single cleanup happens.
>>>>>
>>>>> I'll cross check my code and count my references from
>>>>> application
>>>>> side,
>>>>> but maybe someone else has similar problems?
>>>>>
>>>>> dd
>>>>> -- 
>>>>> Dragiša Durić <dragisha at m3w.org>
>>>>>
>>>>
>>> -- 
>>> Dragiša Durić <dragisha at m3w.org>
>>>
>>
>>
> -- 
> Dragiša Durić <dragisha at m3w.org>

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