Talk:Software transactional memory

I've received some negative feedback about this article from friends. I'm currently researching the area and will improve it in the future. Deco 21:50, 3 February 2006 (UTC)[reply]

What exactly is wrong? countryhacker 20:55, 4 February 2006 (UTC)[reply]

Sorry for not answering, didn't see this. In short it was missing a lot of information, and the English was also a bit messy. I've rewritten it. I hope the original author is not offended - there's plenty of room for additional expansion still. Deco 23:47, 8 February 2006 (UTC)[reply]

KVD, February 2006: The article first mentions that STM has a performance disadvantage on a small number of processors, and then it goes on to say "in addition to its performance benefits, ...". This is a contradiction, or at least confusing. Is the net effect of STM a performance gain or performance loss? Or is there a minimal degree of concurrency (e.g. a minimal number of processors) beyond which STM becomes interesting?

As far as I remember, WORST case (when all but one transactions fail) is O(n) where n is number of concurrent processes. This is definitely not "twice". Maybe it does happen rarely in real world, but is worth mentioning anyway. countryhacker 09:24, 24 February 2006 (UTC)[reply]

Implementation issues

Quoted from the article:

atomic { if (x != y) while (true) { } } Transaction A	atomic { x++; y++; } Transaction B

Provided x=y initially, neither transaction above alters this invariant, but it's possible transaction A will read x after transaction B updates it but read y before transaction B updates it, causing it to enter an infinite loop.

Hmmm - isn't it the point of transactions that the intermediate state "x == y+1" is NOT visible anywhere outside of transaction B? "Commit" is an atomic operation, isn't it??? --84.137.86.147 22:25, 4 March 2006 (UTC)[reply]

Sorry for the fuss. Now I understand that the situation can occur if the thread of transaction A first reads x, then is suspended (for any reason), then transaction B is run completely and finally A resumes and reads the value of y... --84.137.86.147 22:34, 4 March 2006 (UTC)[reply]

Implementations

What exactly qualifies an STM implementation as being "large-scale product-quality"? I know a number of people who are using Haskell/STM in a non-research (at least, not research on STM) context. In other news, Audrey-tan has incorporated STM into Perl 6. (Is this product-quality yet? Or large-scale enough?) Liyang 21:40, 19 June 2006 (UTC)[reply]