# preshing/junction

Concurrent data structures in C++

Repository: https://github.com/preshing/junction
Canonical: https://ross.abutalabs.com/products/junction
Language: C++
License: NOASSERTION
License Family: other
Last push: 2026-05-16T17:22:06+00:00

## Health v2 (maintenance only)
Score: 69/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 82, release rhythm 35, longevity 100
- inputs: {"age_days": 3866, "days_push": 109, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases, no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1459, forks 160 (observed 2026-08-28T04:04:47.260603+00:00)

## What it is
Junction is a C++ library of concurrent data structures, offering several lock-free concurrent hash map implementations such as ConcurrentMap_Leapfrog and ConcurrentMap_Grampa. It builds with CMake and depends on the Turf library.

## Use cases
- use a lock-free concurrent hash map in C++
- share a hash map across multiple threads safely
- high-performance concurrent key-value lookups
- replace mutex-protected std::unordered_map in multithreaded code
- benchmark concurrent map implementations

## When to choose
- you need proven lock-free hash maps in a C++ project
- your build already uses CMake
- you need fine-grained control over concurrency trade-offs across map variants

## When to avoid
- you need general-purpose containers beyond hash maps
- you want a header-only drop-in with no dependencies (Turf is required)
- your project uses a different build system and you dislike vendoring sources

## Facets
- artifact type: library
- maturity: maintenance
- function: concurrency, database, developer-tools
- domain: performance, developer-tools
- platform: cpp, cross-platform, windows
- tags: concurrent-hash-map, lock-free, data-structures, cmake, algorithms, linux, macos

## Member repositories
- preshing/junction (main) score 69

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:47.260603+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T04:35:28.350732+00:00, confidence not recorded.
  - readme: https://github.com/preshing/junction (fetched 2026-08-28T04:04:47.260603+00:00, sha 083a8239bf87)
- Data as of 2026-08-30T08:39:29.467469+00:00.