A collection of hash tables for parallel programming, including lock-free, wait-free tables

lobste.rs - Tue Jan 18 14:35

Hash tables for parallel programming

This project consisists of fast hash tables suitable for parallel programming, including multiple lock-free, wait-free hashtables.

If you're interested in understanding the different algorithms, see the README.md in the src/ directory.

If you're just interested in using the most efficient algorithms in your C applications, see below for instructions.


This project will install libhatrack.a, which exports high-level dictionary and set classes (hatrack_dict and hatrack_set), backed by two appropriate lower-level hash tables. Examples of using these classes are in the examples directory.

The lower-level hash tables can also be used directly; again, look at the src directory.

The hatrack_dict and hatrack_set implementations both support multiple simultaneous readers and multiple simultaneous writers.

You are responsible for all memory management for keys and items; our hash tables only worries about memory management for state internal to the table.


If you downloaded a release distro, you can simply do:

sudo make install

If you cloned the repo, then you'll first need to create the configure script and Makefile.in, using autotools:


If you want to run the test suite, first build it with:

This will create an executable named test in the tests directory, which will run functionality and performance tests for all the different hash table implementations.

There are no library dependencies, beyond bits that are a part of the C11 standard (particularly stdatomic and pthreads). Parallel malloc implementations like jemalloc (http://jemalloc.net) or hoard (http://hoard.org) can be added via LD_PRELOAD, which may boost performance when there's significant concurancy, depending on the system malloc you're using... particularly with hatrack_set objects, which require more dynamic memory allocation than hatrack_dictionary objects do (this is due to sets requiring fully consistent views; see the README.md file in the src directory for more information).

Getting Started

Once you've built, you can just link against the library, and go. See the examples directory.