[Stackless] Tasklet cleanup?

Sylvain Prat sylvain.prat at gmail.com
Sun May 20 00:29:19 CEST 2012


I'm wondering how tasklets can clean themselves up when they are
destroyed due to garbage collection (i.e. when they are not in the
runnables and not referenced by any object anymore). Greenlet solves
this problem by raising a GreenletExit exception in the greenlet's run
function when the greenlet is about to die due to garbage collection.
However, in stackless, it seems that no TaskletExit exception is
raised when the tasklet is about to die, so we can't simply use a
try/finally in the tasklet's callable to clean up resources.

I tried to wrap my tasklet in a parent object which has the same
lifespan as my tasklet and has a __del__ function for cleaning up, but
I keep having problems with circular references (the wrapper/parent
object also provides the callable of the tasklet, i.e. a bound method)
that make the tasklet/parent object uncollectable (circular references
: wrapper --> tasklet --> stackless machinery? --> callable stack
frame (bound method of wrapper) --> wrapper). Same problem when trying
to inherit from tasklet.

So, how can I clean up resources in tasklets? (I'm pretty sure I've
missed something obvious)

Thank in advance,

Sylvain PRAT

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