From 99a39063cb84372556d370f489da845281cc68b0 Mon Sep 17 00:00:00 2001
From: Kacy Fortner <kacy@kacyfortner.com>
Date: Sat, 7 Feb 2026 13:32:53 -0500
Subject: [PATCH] perf: add jemalloc as default allocator

reduces allocation contention under multi-threaded workloads.
profiling showed ~7.7% CPU time spent in malloc/cfree with system
allocator. jemalloc uses per-thread caches to minimize contention.

enabled by default via feature flag. can be disabled with
--no-default-features for platforms that don't support jemalloc.
---
 Cargo.lock                      | 21 +++++++++++++++++++++
 crates/ember-server/Cargo.toml  |  7 +++++++
 crates/ember-server/src/main.rs |  6 ++++++
 3 files changed, 34 insertions(+)

diff --git a/Cargo.lock b/Cargo.lock
index 62b727b0..19b79cf0 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -547,6 +547,7 @@ dependencies = [
  "emberkv-core",
  "metrics",
  "metrics-exporter-prometheus",
+ "tikv-jemallocator",
  "tokio",
  "tracing",
  "tracing-subscriber",
@@ -1937,6 +1938,26 @@ dependencies = [
  "cfg-if",
 ]
 
+[[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 = "tinytemplate"
 version = "1.2.1"
diff --git a/crates/ember-server/Cargo.toml b/crates/ember-server/Cargo.toml
index 69f18bc7..233eb9c3 100644
--- a/crates/ember-server/Cargo.toml
+++ b/crates/ember-server/Cargo.toml
@@ -9,6 +9,10 @@ keywords.workspace = true
 categories.workspace = true
 readme = "README.md"
 
+[features]
+default = ["jemalloc"]
+jemalloc = ["tikv-jemallocator"]
+
 [dependencies]
 bytes = { workspace = true }
 emberkv-core = { workspace = true }
@@ -21,3 +25,6 @@ tracing-subscriber = { workspace = true }
 clap = { workspace = true }
 metrics = { workspace = true }
 metrics-exporter-prometheus = { workspace = true }
+
+# optional: better multi-threaded allocation performance
+tikv-jemallocator = { version = "0.6", optional = true }
diff --git a/crates/ember-server/src/main.rs b/crates/ember-server/src/main.rs
index 981beb0f..6086b2f7 100644
--- a/crates/ember-server/src/main.rs
+++ b/crates/ember-server/src/main.rs
@@ -1,3 +1,9 @@
+// use jemalloc as the global allocator for better multi-threaded performance.
+// reduces allocation contention compared to the default system allocator.
+#[cfg(feature = "jemalloc")]
+#[global_allocator]
+static GLOBAL: tikv_jemallocator::Jemalloc = tikv_jemallocator::Jemalloc;
+
 mod config;
 mod connection;
 mod metrics;