From 95803a44c54fb6ac0fd21b694191d147a1a2d314 Mon Sep 17 00:00:00 2001
From: Harnoor Lal <harlal902@gmail.com>
Date: Fri, 27 Feb 2026 10:31:34 -0800
Subject: [PATCH] perf: use jemalloc as global allocator on Linux

musl's allocator makes 3,200+ mmap/munmap/brk syscalls for chainsaw's
workload (~64 allocs/file, 85% <= 64 bytes). jemalloc services the same
workload with 23 syscalls.

A/B on Linux VPS (wrangler cold, 3447 modules): 531ms -> 329ms (1.61x).
macOS is neutral (libmalloc is already magazine-based).

Uses target-conditional dep so macOS never compiles jemalloc.

Closes #178
---
 Cargo.lock  | 21 +++++++++++++++++++++
 Cargo.toml  |  3 +++
 src/main.rs |  4 ++++
 3 files changed, 28 insertions(+)

diff --git a/Cargo.lock b/Cargo.lock
index 5644c1c..a6d82cd 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -250,6 +250,7 @@ dependencies = [
  "serde_json",
  "stats",
  "tempfile",
+ "tikv-jemallocator",
  "tree-sitter",
  "tree-sitter-python",
 ]
@@ -2620,6 +2621,26 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "tikv-jemalloc-sys"
+version = "0.6.1+5.3.0-1-ge13ca993e8ccb9ba9847cc330696e02839f328f7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cd8aa5b2ab86a2cefa406d889139c162cbb230092f7d1d7cbc1716405d852a3b"
+dependencies = [
+ "cc",
+ "libc",
+]
+
+[[package]]
+name = "tikv-jemallocator"
+version = "0.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0359b4327f954e0567e69fb191cf1436617748813819c94b8cd4a431422d053a"
+dependencies = [
+ "libc",
+ "tikv-jemalloc-sys",
+]
+
 [[package]]
 name = "tinystr"
 version = "0.8.2"
diff --git a/Cargo.toml b/Cargo.toml
index dd618e6..29ad17d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -37,6 +37,9 @@ rustyline = "15"
 gix = { version = "0.79.0", default-features = false, features = ["max-performance-safe"] }
 notify = { version = "7", default-features = false, features = ["macos_fsevent"] }
 
+[target.'cfg(target_os = "linux")'.dependencies]
+tikv-jemallocator = "0.6"
+
 [lib]
 name = "chainsaw"
 path = "src/lib.rs"
diff --git a/src/main.rs b/src/main.rs
index be5941e..91bb39b 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,6 +1,10 @@
 // compact_str 0.8 (oxc_span) + 0.9 (oxc_resolver) — transitive, out of our control.
 #![allow(clippy::multiple_crate_versions)]
 
+#[cfg(target_os = "linux")]
+#[global_allocator]
+static GLOBAL: tikv_jemallocator::Jemalloc = tikv_jemallocator::Jemalloc;
+
 use std::io::IsTerminal;
 use std::path::{Path, PathBuf};
 use std::sync::Arc;