mimalloc-pprof 0.8.1

mimalloc global allocator with pprof-compatible sampled heap profiling (mimalloc v2 engine)
Documentation

mimalloc-pprof (v2 engine)

mimalloc as a Rust global allocator, with pprof-compatible sampled heap profiling built in. Windows is a first-class target alongside Linux and macOS.

Dumps open directly in google/pprof for flame graphs, call graphs, top reports, and profile diffs.

This is the 0.8.x line, built on the mimalloc v2 engine. The current line is 0.9.x, built on mimalloc v3, and is what most users should take. The profiler API, environment variables, and output formats are identical, so moving between them is a version bump rather than a code change. 0.8.x remains available for anyone who prefers the longer-established v2 allocator.

Upgrade note for 0.8.0 users

0.8.0 leaks memory on Windows/MinGW and should not be used. Every exiting thread leaked its thread-local heap and pages — about 0.24 GB per stress iteration, reaching 23.5 GB at 100 iterations, growing without bound. The process still exited successfully, so it was invisible on a large-memory machine and only surfaced as an out-of-memory failure on a smaller one.

0.8.1 fixes it: flat at 0.28 GB across the same run. MSVC builds were never affected. Details in issue #47.

Usage

[dependencies]
mimalloc-pprof = "0.8"

[profile.release]
debug = "line-tables-only"
strip = false

use mimalloc_pprof::{prof, MiMalloc};
use std::path::Path;

#[global_allocator]
static ALLOCATOR: MiMalloc = MiMalloc;

fn main() -> std::io::Result<()> {
    assert!(prof::start(0), "profiler already running"); // 0 = default, ~512 KiB

    let retained = vec![0_u8; 1024 * 1024];
    prof::dump_file(Path::new("heap.prof"))?;            // dump while still live
    std::hint::black_box(&retained);

    prof::stop();
    Ok(())
}

Then:

pprof -http=:0 ./target/release/my_app heap.prof

Or profile without touching the code at all:

MIMALLOC_PROF=1 MIMALLOC_PROF_DUMP_AT_EXIT=heap.prof ./my_app

Notes

  • On Linux and macOS, keep frame pointers for reliable stack walking: rustflags = ["-Cforce-frame-pointers=yes"] in .cargo/config.toml. Windows x64 uses unwind information instead — keep the PDB.
  • Do not link a second mimalloc into the same process; this crate vendors its own.
  • The per-heap allocator statistics (ProfStats::heap) are a v3 feature and are not available on this line.

Full documentation is in the repository README.

License

MIT, the same as upstream mimalloc.