+1 (previously reviewed on the panama-dev list) It’s very pleasing to see this get simplified through some good collaboration. StampedLock is quite powerful, and likely an under utilized resource.
Paul. > On May 28, 2020, at 4:20 AM, Maurizio Cimadamore > <[email protected]> wrote: > > Hi, > during the review of [1] it emerged that the implementation of the memory > scope abstraction (which is used to keep track of temporal scope of a memory > segment) does not scale well in situations where there is a lot of contention > on the acquire() method due to many threads working simultaneously on > different chunks of the segment. > > Peter has proposed an alternate implementation [2] which, instead of using > CAS, it cleverly uses LongAdders. > > While that implementation worked correctly, we managed to simplify it > further, by realizing that what we needed here was an instance of a > read-write lock: a thread that acquires a segment does a "read", while a > thread closing a segment does a "write". By using optimistic reads with a > StampedLock we were able to gain back scalability and maintain the code > relatively readable. > > Webrev: > > http://cr.openjdk.java.net/~mcimadamore/8246050/webrev/ > > Cheers > Maurizio > > [1] - > https://mail.openjdk.java.net/pipermail/core-libs-dev/2020-April/066136.html > [2] - https://git.openjdk.java.net/panama-foreign/pull/142 >
