orchistro / perf_test_associative_maps

Performance test of associative maps/sets for eliminating duplicate items

Test result: (unit:seconds taken)

container type	emplace	try_emplace
set	24.85	21.57
unordered_set	10.36	8.09
map	25.31	19.55
unordered_map	7.79	10.37

std::set

$ /usr/bin/time ./foo set emplace 10000000
24.49user 0.38system 0:24.85elapsed 100%CPU (0avgtext+0avgdata 499908maxresident)k
0inputs+0outputs (0major+125012minor)pagefaults 0swaps

$ /usr/bin/time ./foo set try_emplace 10000000
21.26user 0.32system 0:21.57elapsed 100%CPU (0avgtext+0avgdata 500116maxresident)k
0inputs+0outputs (0major+125064minor)pagefaults 0swaps

std::unordered_set

$ /usr/bin/time ./foo unordered_set emplace 10000000
9.99user 0.36system 0:10.36elapsed 100%CPU (0avgtext+0avgdata 475972maxresident)k
0inputs+0outputs (0major+133309minor)pagefaults 0swaps

$ /usr/bin/time ./foo unordered_set try_emplace 10000000
7.80user 0.29system 0:08.09elapsed 100%CPU (0avgtext+0avgdata 476032maxresident)k
0inputs+0outputs (0major+133324minor)pagefaults 0swaps

std::map

$ /usr/bin/time ./foo map emplace 10000000
24.91user 0.42system 0:25.31elapsed 100%CPU (0avgtext+0avgdata 583328maxresident)k
0inputs+0outputs (0major+145867minor)pagefaults 0swaps

$ /usr/bin/time ./foo map try_emplace 10000000
19.21user 0.35system 0:19.55elapsed 100%CPU (0avgtext+0avgdata 583144maxresident)k
0inputs+0outputs (0major+145821minor)pagefaults 0swaps

std::unordered_map

$ /usr/bin/time ./foo unordered_map emplace 10000000
7.43user 0.36system 0:07.79elapsed 100%CPU (0avgtext+0avgdata 559104maxresident)k
0inputs+0outputs (0major+154092minor)pagefaults 0swaps

$ /usr/bin/time ./foo unordered_map try_emplace 10000000
9.94user 0.44system 0:10.37elapsed 100%CPU (0avgtext+0avgdata 559044maxresident)k
0inputs+0outputs (0major+154077minor)pagefaults 0swaps

The test shows somewhat surprising result: the winner is std::unordered_map using emplace(), not std::unordered_set using try_emplace(). But the difference is very small compared to the second winner std::unordered_set using try_emplace().

Deciding what to use is up to you.