zimalloc

zimalloc is general purpose allocator for Zig, inspired by mimalloc.

Status

This project is under development and should currently be considered experimental/exploratory; there is no documentation and it has not been battle-tested. In particular there may be issues with multi-threaded workloads. Contributions of any kind (PRs, suggestions for improvements, resources or ideas related to benchmarking or testing) are welcome.

The allocator is significantly faster than std.heap.GeneralPurposeAllocator(.{}) but should not (yet) be expected to be competitive with other established general purpose allocators.

Usage

To use the allocator in your own project you can use the Zig package manager by putting this in your build.zig

pub fn build(b: *std.Build) void {
    // -- snip --
    const zimalloc = b.dependency("zimalloc").module("zimalloc"); // get the zimalloc module
    // -- snip --
    exe.addModule(zimalloc); // add the zimalloc module as a dependency of exe
    // -- snip --
}

and this to the dependencies section of your build.zig.zon

    .zimalloc = .{
        .url = "https://github.com/dweiller/zimalloc/archive/[[COMMIT_SHA]].tar.gz"
    },

where [[COMMIT_SHA]] should be replaced with full SHA of the desired revision. You can then import and initialise an instance of the allocator as follows:

const zimalloc = @import("zimalloc");
pub fn main() !void {
    var gpa = try zimalloc.Allocator(.{}){};
    defer gpa.deinit();

    const allocator = gpa.allocator();
    // -- snip --
}

Shared library

There is a shared library that can be used for overriding standard libc allocation functions. It can be accessed from your build.zig like so:

pub fn build(b: *std.Build) void {
    // -- snip --
    const libzimalloc = b.dependency("zimalloc").artifact("zimalloc"); // get the zimalloc shared library
    // -- snip --
    exe.linkLibrary(zimalloc); // link to libzimalloc
    // -- snip --
}

If you just want to build the shared library and use it outside the Zig build system, you can build it with the libzimalloc or install steps, for example:

zig build libzimalloc -Doptimize=ReleaseSafe

Notes

• The current implementation works on Linux, with other systems untested.
• The main suite of tests currently used is https://github.com/daanx/mimalloc-bench which are run using LD_PRELOAD. Not all tests have been tried, but all those that have been tested run successfully.
• No attempt has been made to make the allocator signal-safe.