[Stackless] sys.settrace bug

[John Ehresman]

Kristján Valur Jónsson wrote:
> Tracing / profiling in stackless is broken.
> I have a workaround here, basically a "global tracing flag" where I disable stackless trying to maintain a separate tracing flag for each tasklet, and just keep it thread global.
> One of the things I want to discuss with Christian

A global tracer callback would be preferable from my perspective than 
per-thread callbacks.  I wouldn't want to require a specially patched 
interpreter though.

Cheers,

John