Choosing an Allocator¶

Grafeo allocates through Rust's global allocator and does not pick one for you: by default that is the system allocator, and Grafeo's tests and benchmarks run on it. A Rust application chooses its allocator once, in its own binary, with #[global_allocator]. Every allocation Grafeo makes in that process then goes through it, with no change to Grafeo or its features.

The bindings (Python, Node.js, WebAssembly, C and the languages built on it) ship a fixed build with the system allocator.

mimalloc¶

[dependencies]
grafeo = "0.6"
mimalloc = "0.1"

#[global_allocator]
static GLOBAL: mimalloc::MiMalloc = mimalloc::MiMalloc;

jemalloc¶

jemalloc builds on Linux and macOS, not with the MSVC toolchain on Windows, so depend on it only where it builds.

[dependencies]
grafeo = "0.6"

[target.'cfg(not(target_env = "msvc"))'.dependencies]
tikv-jemallocator = "0.7"

#[cfg(not(target_env = "msvc"))]
#[global_allocator]
static GLOBAL: tikv_jemallocator::Jemalloc = tikv_jemallocator::Jemalloc;

rusty_alloc¶

rusty_alloc is a Rust port of mimalloc without C code. Its global allocator is in the rusty_alloc-api crate. The crate is young and releases often: pin the exact version you have tested, and read its changelog before you move to a newer one.

[dependencies]
grafeo = "0.6"
rusty_alloc-api = "=2.2.6"

#[global_allocator]
static GLOBAL: rusty_alloc_api::RustyAlloc = rusty_alloc_api::RustyAlloc;

One Allocator Per Process¶

A process has one global allocator, and declaring a second one fails to link. The grafeo crate's jemalloc and mimalloc-allocator features declare one for you: use either a feature or your own #[global_allocator], not both. The same holds for any other dependency that installs an allocator when you depend on it.

Measure with your own workload before you switch: an allocator that is faster on one workload can use more memory, or be slower, on another.