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BTreeMap/BTreeSet::from_iter: use bulk building to improve the performance Bulk building is a common technique to increase the performance of building a fresh btree map. Instead of inserting items one-by-one, we sort all the items beforehand then create the BtreeMap in bulk. Benchmark ``` ./x.py bench library/alloc --test-args btree::map::from_iter ``` * Before ``` test btree::map::from_iter_rand_100 ... bench: 3,694 ns/iter (+/- 840) test btree::map::from_iter_rand_10_000 ... bench: 1,033,446 ns/iter (+/- 192,950) test btree::map::from_iter_seq_100 ... bench: 5,689 ns/iter (+/- 1,259) test btree::map::from_iter_seq_10_000 ... bench: 861,033 ns/iter (+/- 118,815) ``` * After ``` test btree::map::from_iter_rand_100 ... bench: 3,033 ns/iter (+/- 707) test btree::map::from_iter_rand_10_000 ... bench: 775,958 ns/iter (+/- 105,152) test btree::map::from_iter_seq_100 ... bench: 2,969 ns/iter (+/- 336) test btree::map::from_iter_seq_10_000 ... bench: 258,292 ns/iter (+/- 29,364) ``` |
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| alloc | ||
| backtrace@4f925f8d81 | ||
| core | ||
| panic_abort | ||
| panic_unwind | ||
| proc_macro | ||
| profiler_builtins | ||
| rtstartup | ||
| rustc-std-workspace-alloc | ||
| rustc-std-workspace-core | ||
| rustc-std-workspace-std | ||
| std | ||
| stdarch@89b0e355bc | ||
| test | ||
| unwind | ||