fix(memory): enable jemalloc background_thread by default

pgdog/Cargo.toml

@@ -92,6 +92,7 @@ libc = "0.2"
 
 [target.'cfg(not(target_env = "msvc"))'.dependencies]
 tikv-jemallocator = "0.6"
+tikv-jemalloc-ctl = "0.6"
 
 
 [build-dependencies]

pgdog/src/lib.rs

@@ -52,6 +52,17 @@ static GLOBAL: tikv_jemallocator::Jemalloc = tikv_jemallocator::Jemalloc;
 #[global_allocator]
 static GLOBAL: &stats_alloc::StatsAlloc<System> = &stats_alloc::INSTRUMENTED_SYSTEM;
 
+/// Enable jemalloc's background purge threads so freed memory is returned to
+/// the OS after allocation bursts.
+#[cfg(all(not(test), not(target_env = "msvc")))]
+pub fn enable_jemalloc_background_thread() {
+    let _ = tikv_jemalloc_ctl::background_thread::write(true);
+}
+
+/// No-op fallback where jemalloc is not the active allocator.
+#[cfg(any(test, target_env = "msvc"))]
+pub fn enable_jemalloc_background_thread() {}
+
 /// Filter that dynamically installs or removes an inner
 /// [`TracingRateLimitLayer`] at runtime.
 ///

pgdog/src/main.rs

@@ -19,6 +19,8 @@ use tokio::runtime::Builder;
 use tracing::{error, info, warn};
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
+    pgdog::enable_jemalloc_background_thread();
+
     let args = cli::Cli::parse();
     let command = args.command.clone();
     let mut overrides = pgdog::config::Overrides::default();