RUrurban·Mar 30, 2026Recommendation phrase
Not really comprehesive. Doesn't include my favorite
https://github.com/greg7mdp/parallel-hashmap which adds thread-safety to performance.
In Comprehensive C++ Hashmap Benchmarks (2022)greg7mdp
parallel-hashmap
C++2019–2026
greg7mdp / parallel-hashmap
parallel-hashmap
A family of header-only, very fast and memory-friendly hashmap and btree containers.
6Distinct people
10Mentions
1Explicit recommenders
3.2KGitHub stars
What to know before exploring
What it is
A family of header-only, very fast and memory-friendly hashmap and btree containers.
GitHub
Where it is used
No documented product use has been verified yet.
What people are saying
Not really comprehesive. Doesn't include my favorite https://github.com/greg7mdp/parallel-hashmap which adds thread-safety to performance.
rurban used a recommendation phrase. One indexed comment matches. This is a phrase match, not a verdict.
No classified warning is attached to this page. Read the discussions before treating silence as approval.
Also in these discussions
No other repository is repeatedly linked in the same discussions.
This week on Hacker News
Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 12:54:37 PM UTC.
No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.
Mentions over time
HN mentions by year10 dated mentions
Observed mentions: 2019-03-31 23:13:21 UTC to 2026-03-30 14:20:18 UTC.
* An incomplete calendar period is marked with an outlined bar. Its count is not directly comparable with a full period.
Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.
View mention counts and date ranges
| Period | Start (UTC) | End (exclusive, UTC) | Mentions | Submissions | Comments |
|---|---|---|---|---|---|
| 2019 | 2019-01-01 00:00:00 UTC | 2020-01-01 00:00:00 UTC | 3 | 1 | 2 |
| 2020 | 2020-01-01 00:00:00 UTC | 2021-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2021 | 2021-01-01 00:00:00 UTC | 2022-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2022 | 2022-01-01 00:00:00 UTC | 2023-01-01 00:00:00 UTC | 2 | 1 | 1 |
| 2023 | 2023-01-01 00:00:00 UTC | 2024-01-01 00:00:00 UTC | 0 | 0 | 0 |
| 2024 | 2024-01-01 00:00:00 UTC | 2025-01-01 00:00:00 UTC | 1 | 0 | 1 |
| 2025 | 2025-01-01 00:00:00 UTC | 2026-01-01 00:00:00 UTC | 2 | 1 | 1 |
| 2026 (partial) | 2026-01-01 00:00:00 UTC | 2027-01-01 00:00:00 UTC | 2 | 0 | 2 |
What Hacker News says
10 sourcesConcurrentSwissMap exists for years already: https://github.com/greg7mdp/parallel-hashmap
Just in C++, not Java.
In Concurrent Hash Table DesignsBy default they are not thread safe, i.e., they offer the same thread safety as std::map or any stdlib type; however, the map can optionally be made thread safe and is apparently optimized for this usage. Details at: https://github.com/greg7mdp/parallel-hashmap?tab=readme-ov-f....
In Parallel-hashmap: drop-in replacement for unordered_map, unordered_setParallel-hashmap: drop-in replacement for unordered_map, unordered_set
62 points · Open discussionStandard library maps/unordered_maps are themselves notoriously slow anyway. A flat_hash_map from abseil or parallel-hashmaps[1] would be better.
[1] https://github.com/greg7mdp/parallel-hashmap
In The One Billion Row Challenge in CUDAThen they should really try https://github.com/greg7mdp/parallel-hashmap, the current state of the art.
In How to build a chess enginePerformance is very similar to my header-only version of the Abseil's hash tables available at https://github.com/greg7mdp/parallel-hashmap.
In Open-sourcing F14 for memory-efficient hash tablesYou may want to try my version of the Abseil hash tables (I updated the code to make them header-only) at https://github.com/greg7mdp/parallel-hashmap.
In Open-sourcing F14 for memory-efficient hash tablesNew: A header-only, Abseil-derived hash table family
2 points · Open discussion