3 November 2006

I recently started tracking the Stackless Python mailing list. I've been interested in Stackless, the brainchild of the fearsomely clever Christian Tismer, for some time now. I recently acquired a client with active interests in that area, so it behooves me to stay up to date.

Stackless allows you to organise your work into tasklets (which as far as I understand it have replaced the original microthreads as the unit for scheduling: this is all pretty new to me, so apologies if it's incorrect). An interesting thing about tasklets is that you can pickle them, pass the pickle to another computer, unpickle them and resume the tasklet in the new environment.

My attention was grabbed by one recent thread in which a user explains that he was trying to perform such interactions across a heterogeneous environment with Power PC, SPARC and Intel-based CPUs and found that it worked between SPARC and PPC, but the Intel architecture appeared to be failing -- presumably due to the different endianness.

After a couple of messages surmising that this was hardly surprising, Christian came into the thread to explain that there was no architecture-dependent code in the pickled thread resumption functionality. Lo and behold, the original poster came back explaining:

I must apologize, it turns out my problem was due to the fact that I was using a different version of stackless on the intel machine. In case anyone is curious, resuming pickled tasklets across architectures is easy. Thank you for your replies!

Let me repeat that, just in case you missed it: resuming pickled tasklets across architectures is easy. As far as I can see this gives Python an amazing capability to produce applications with highly-distributed architectures. It's going to be interesting to see where Stackless goes with this, but it should be shouted from the rooftops. This is an advanced feature that represents a real advantage for (Stackless) Python in a world where everyone is wondering how they can accommodate the new multicore processors.

With Stackless, your CPUs don't even need to have the same architecture, but the feature will work just as well in the homogeneous environment that multi-processor computers provide.