[Stackless] Tasklet Slot Inheritance
tismer at stackless.com
Sun May 20 20:42:40 CEST 2007
On 20.05.2007, at 19:16, Kristján Valur Jónsson wrote:
>> -----Original Message-----
>> From: stackless-bounces at stackless.com [mailto:stackless-
>> bounces at stackless.com] On Behalf Of Richard Tew
>> When a tasklet is killed, it has its references cleared through the
>> tp_clear method. This is part of the Python type implementation and
>> clears various references in order to prevent or break reference
>> cycles. Including, as observed here, the slots.
> tp_clear() is supposed to be called by the garbage collector when
> it so chooses. It is not usually something that should be manually
> invoked. I am curious as to why this was added. There must have
> been a good reason, since this is highly unorthodox. Maybe
> Christian can recall?
I wanted to have a way to really break a tasklet. I think the main
was the existance of those stack slices in hard-switching.
The problem is that these stack slices create references to objects
which cannot be garbage collected. Therefore, I needed to explicitly
peel everything out of the tasklet myself to loose as many as possible
IOW., I need to call tp_clear here, because the GC fails to do it,
because references coming from stack slices are not detected and GC
never gets called.
Maybe it is possible to do a less crude cleanup, preserving user
if you think it is worth the effort.
cheers - chris
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