Jakub KonkaandCole Miller
f4aa279898
Here's some backstory: * on macOS, @cole-miller and I noticed that since roughly Oct 2025, due to some changes to latest macOS Tahoe, for any spawned child process we needed to reset Mach exception ports (https://github.com/zed-industries/zed/issues/36754 + https://github.com/RemiKalbe/zed/commit/6e8f2d2ebe5a93753625a3026aeb996de8cb436b) * the changes in that PR achieve that via `pre_exec` hook on `std::process::Command` which then abandons `posix_spawn` syscall for `fork` + `execve` dance on macOS (we tracked it down in Rust's std implementation) * as it turns out, `fork` + `execve` is pretty expensive on macOS (apparently way more so than on other OSes like Linux) and `fork` takes a process-wide lock on the allocator which is bad * however, since we wanna reset exception ports on the child, the only official way supported by Rust's std is to use `pre_exec` hook * posix_spawn on macOS exposes this tho via a macOS specific extension to that syscall `posix_spawnattr_setexceptionports_np` but there is no way to use that via any standard interfaces in `std::process::Command` * thus, it seemed like a good idea to instead create our own custom Command wrapper that on non-macOS hosts is a zero-cost wrapper of `smol::process::Command`, while on macOS we reimplement the minimum to achieve `smol::process::Command` with `posix_spawn` under-the-hood Notably, this changeset improves git-blame in very large repos significantly. Release Notes: - Fixed performance spawning child processes on macOS by always forcing `posix_spawn` no matter what. --------- Co-authored-by: Cole Miller <cole@zed.dev>
Eval
This eval assumes the working directory is the root of the repository. Run it with:
cargo run -p eval
The eval will optionally read a .env file in crates/eval if you need it to set environment variables, such as API keys.
Explorer Tool
The explorer tool generates a self-contained HTML view from one or more thread JSON file. It provides a visual interface to explore the agent thread, including tool calls and results. See ./docs/explorer.md for more details.
Usage
cargo run -p eval --bin explorer -- --input <path-to-json-files> --output <output-html-path>
Example:
cargo run -p eval --bin explorer -- --input ./runs/2025-04-23_15-53-30/fastmcp_bugifx/*/last.messages.json --output /tmp/explorer.html