It's Fiddly

"Mental" writes in a comment (i've started a new post) to my rant on transactional memory...

I was having fun implementing STM until I realized that I was able to implement the Actor model correctly in a few hours, versus several weeks for getting the fiddly aspects of STM down.

Good tag line... "Transactional Memory: It's Fiddly!!!"

Here's the entire comment because I like it...

Having written several implementations of both STM and various message-passing-based concurrency models for Ruby lately, I'm a lot less sunny on STM than I used to be even a few weeks ago.

I was having fun implementing STM until I realized that I was able to implement the Actor model correctly in a few hours, versus several weeks for getting the fiddly aspects of STM down.

The biggest immediate problem for STM is starvation -- a large transaction can just keep retrying, and I'm not sure there is a way to address that without breaking composability. ...and composability is the whole raison d'etre of STM in the first place.