[loeg]

Sort of tl;dr: mimalloc doesn't actually free memory in a way that it can be reused on threads other than the one that allocated it; the free call marks regions for eventual delayed reclaim by the original thread. If the original thread calls malloc again, those regions are collected (1/N malloc calls). Or (C) you can explicitly invoke mi_collect[1] in the allocating thread (the Rust crate does not seem to expose this API).

[1]: https://github.com/microsoft/mimalloc/blob/dev/src/heap.c#L1...

[Arnavion]

The mimalloc crate just provides the GlobalAlloc impl that can be registered with libstd as the global allocator using the `#[global_allocator]` attr.

The underlying sys crate provides the binding for mimalloc API like `mi_collect`: https://docs.rs/libmimalloc-sys/0.1.39/libmimalloc_sys/fn.mi...