Re:How innovative is Clojure as a Lisp dialect from Lisp exp...
by kccqzy on Monday January 07, 2019 @04:08AM
(#18843833)
STM is indeed non-deterministic in performance, but non-determinism is basically a given in all concurrency problems.
In the same vein you can also say locks have non-deterministic performance characteristics: I never know how long I'm going to wait when I'm trying to acquire the lock! In other MVCC scenarios such as databases you also don't know whether your final COMMIT will fail due to concurrent writes and you have to retry.
Furthermore Clojure's STM in fact has an extra primitive called commute that is not present in Haskell's STM. It makes commutative changes even faster.
In the same vein you can also say locks have non-deterministic performance characteristics: I never know how long I'm going to wait when I'm trying to acquire the lock! In other MVCC scenarios such as databases you also don't know whether your final COMMIT will fail due to concurrent writes and you have to retry.
Furthermore Clojure's STM in fact has an extra primitive called commute that is not present in Haskell's STM. It makes commutative changes even faster.