Enable jemalloc profiling support by default

Include `tikv-jemalloc-sys` in the `jemalloc` feature to allow runtime heap
profiling without requiring a rebuild. Profiling remains inactive by default
(`prof_active:false`) and must be explicitly enabled via the HTTP API.

Author: jimmygchen

common/malloc_utils/Cargo.toml

@@ -7,7 +7,6 @@ edition = { workspace = true }
 [features]
 mallinfo2 = []
 jemalloc = ["tikv-jemallocator", "tikv-jemalloc-ctl", "tikv-jemalloc-sys"]
-jemalloc-profiling = ["jemalloc", "tikv-jemallocator/profiling"]
 
 [dependencies]
 libc = "0.2.79"
@@ -17,7 +16,7 @@ tikv-jemalloc-ctl = { version = "0.6.0", optional = true, features = ["stats"] }
 tikv-jemalloc-sys = { version = "0.6.0", optional = true }
 
 [target.'cfg(not(target_os = "linux"))'.dependencies]
-tikv-jemallocator = { version = "0.6.0", optional = true, features = ["stats"] }
+tikv-jemallocator = { version = "0.6.0", optional = true, features = ["stats", "profiling"] }
 
 # Jemalloc's background_threads feature requires Linux (pthreads).
 [target.'cfg(target_os = "linux")'.dependencies]

common/malloc_utils/src/jemalloc.rs

@@ -11,10 +11,8 @@
 use metrics::{
     set_gauge, set_gauge_vec, try_create_int_gauge, try_create_int_gauge_vec, IntGauge, IntGaugeVec,
 };
-#[cfg(feature = "jemalloc-profiling")]
 use std::ffi::{c_char, c_int};
 use std::sync::LazyLock;
-#[cfg(feature = "jemalloc-profiling")]
 use std::{mem, ptr};
 use tikv_jemalloc_ctl::{arenas, epoch, raw, stats, Access, AsName, Error};
 
@@ -130,7 +128,6 @@ pub fn page_size() -> Result<usize, Error> {
 }
 
 /// A convenience wrapper around `mallctl` for writing `value` to `name`.
-#[cfg(feature = "jemalloc-profiling")]
 pub unsafe fn mallctl_write<T>(name: &[u8], mut value: T) -> Result<(), c_int> {
     // Use `tikv_jemalloc_sys::mallctl` directly since the `jemalloc_ctl::raw`
     // functions artifically limit the `name` values.
@@ -162,7 +159,6 @@ fn terminate_string_for_c(s: &str) -> Vec<u8> {
 ///
 /// This generates a heap profile at `filename`.
 #[allow(dead_code)]
-#[cfg(feature = "jemalloc-profiling")]
 pub fn prof_dump(filename: &str) -> Result<(), String> {
     let terminated_filename = terminate_string_for_c(filename);
 
@@ -179,7 +175,6 @@ pub fn prof_dump(filename: &str) -> Result<(), String> {
 ///
 /// Controls wether profile sampling is active.
 #[allow(dead_code)]
-#[cfg(feature = "jemalloc-profiling")]
 pub fn prof_active(enable: bool) -> Result<(), String> {
     unsafe { mallctl_write("prof.active\0".as_ref(), enable) }
         .map_err(|e| format!("Failed to call prof.active on mallctl with code {e:?}"))

common/malloc_utils/src/lib.rs

@@ -45,6 +45,8 @@ mod interface {
     pub use crate::glibc::configure_glibc_malloc as configure_memory_allocator;
     pub use crate::glibc::scrape_mallinfo_metrics as scrape_allocator_metrics;
 
+    #[allow(dead_code)]
+    pub use super::prof_active_unsupported as prof_active;
     #[allow(dead_code)]
     pub use super::prof_dump_unsupported as prof_dump;
 }
@@ -56,17 +58,9 @@ mod interface {
         Ok(())
     }
 
-    pub use crate::jemalloc::scrape_jemalloc_metrics as scrape_allocator_metrics;
-
-    #[cfg(not(feature = "jemalloc-profiling"))]
-    pub use super::prof_dump_unsupported as prof_dump;
-    #[cfg(feature = "jemalloc-profiling")]
-    pub use crate::jemalloc::prof_dump;
-
-    #[cfg(not(feature = "jemalloc-profiling"))]
-    pub use super::prof_active_unsupported as prof_active;
-    #[cfg(feature = "jemalloc-profiling")]
     pub use crate::jemalloc::prof_active;
+    pub use crate::jemalloc::prof_dump;
+    pub use crate::jemalloc::scrape_jemalloc_metrics as scrape_allocator_metrics;
 }
 
 #[cfg(all(
@@ -93,7 +87,7 @@ mod interface {
 pub fn prof_dump_unsupported(_: &str) -> Result<(), String> {
     Err(
         "Profile dumps are only supported when Lighthouse is built for Linux \
-        using the `jemalloc` and `jemalloc-profiling` features."
+        using the `jemalloc` feature."
             .to_string(),
     )
 }
@@ -102,7 +96,7 @@ pub fn prof_dump_unsupported(_: &str) -> Result<(), String> {
 pub fn prof_active_unsupported(_: bool) -> Result<(), String> {
     Err(
         "Enabling profiling is only supported when Lighthouse is built for Linux \
-        using the `jemalloc` and `jemalloc-profiling` features."
+        using the `jemalloc` feature."
             .to_string(),
     )
 }

lighthouse/Cargo.toml

@@ -38,8 +38,6 @@ console-subscriber = ["console-subscriber/default"]
 
 # Deprecated. This is now enabled by default on non windows targets.
 jemalloc = []
-# Enable profiling in jemalloc.
-jemalloc-profiling = ["malloc_utils/jemalloc-profiling"]
 
 [dependencies]
 account_manager = { "path" = "../account_manager" }