Joe Seigh wrote: > Martin v. Löwis wrote: >> You still didn't say what you would suggest to make it thread-safe >> again; most likely, you proposal would be to add locking. If I >> understand Joe's approach correctly, he has a solution that does >> not involve locking (although I don't understand how it works). >> > Sun had applied for a patent on it. You can go to the > uspto search page here http://www.uspto.gov/patft/index.html > and look for > > 20060218561 Code preparation technique employing lock-free pointer > operations > 20060037026 Lightweight reference counting using single-target > synchronization > > Click on the images link on the patent application where the illustrations > are which show the concepts probably better than the text. > > The first one above is actually a continuation patent on three different > techniques. One using double wide compare and swap, one using ROP (Repeat > Offender Problem), a form of PDR, and one using DCAS (compare and swap > of two separate locations) which only exists on MC68020 and MC68030 > processors. > Check out the work in the '80s from the NYU Ultra project. They did a great deal of work on using atomic incr/decr for all sorts of algorithms to get around locking on parallel processors.
Chaz. -- http://mail.python.org/mailman/listinfo/python-list
