Comment made by: michalmarczyk
Hi Aaron,
Thanks for looking into this!
From what I've been able to observe, this change hugely improves {{zipmap}} times for large maps. For small maps, there is a small improvement. Here are two basic Criterium benchmarks ({{transient-zipmap}} defined at the REPL as in the patch):
`
;;; large map
user=> (def xs (range 16384))
'user/xs
user=> (last xs)
16383
user=> (c/bench (zipmap xs xs))
Evaluation count : 13920 in 60 samples of 232 calls.
Execution time mean : 4.329635 ms
Execution time std-deviation : 77.791989 us
Execution time lower quantile : 4.215050 ms ( 2.5%)
Execution time upper quantile : 4.494120 ms (97.5%)
nil
user=> (c/bench (transient-zipmap xs xs))
Evaluation count : 21180 in 60 samples of 353 calls.
Execution time mean : 2.818339 ms
Execution time std-deviation : 110.751493 us
Execution time lower quantile : 2.618971 ms ( 2.5%)
Execution time upper quantile : 3.025812 ms (97.5%)
Found 2 outliers in 60 samples (3.3333 %)
low-severe 2 (3.3333 %)
Variance from outliers : 25.4675 % Variance is moderately inflated by outliers
nil
;;; small map
user=> (def ys (range 16))
'user/ys
user=> (last ys)
15
user=> (c/bench (zipmap ys ys))
Evaluation count : 16639020 in 60 samples of 277317 calls.
Execution time mean : 3.803683 us
Execution time std-deviation : 88.431220 ns
Execution time lower quantile : 3.638146 us ( 2.5%)
Execution time upper quantile : 3.935160 us (97.5%)
nil
user=> (c/bench (transient-zipmap ys ys))
Evaluation count : 18536880 in 60 samples of 308948 calls.
Execution time mean : 3.412992 us
Execution time std-deviation : 81.338284 ns
Execution time lower quantile : 3.303888 us ( 2.5%)
Execution time upper quantile : 3.545549 us (97.5%)
nil
`
Clearly the semantics are preserved provided transients satisfy their contract.
I think I might not have started a ggroup thread for this, sorry.
