perf(memory): cap idle pools and bound maintenance queue

Author: Lemonawa

README.md

@@ -70,6 +70,7 @@ cargo build --release
 - `memory_threshold`: 混合模式阈值（默认 100MB）
 - `memory_buffer`: 内存安全缓冲区（默认 100MB）
 - `memory_max_file_mb`: 内存模式文件大小上限（建议稳定优先时设为 16~32）
+- `download.pool_max_idle_per_host`: 下载/命令通道连接池每主机空闲连接上限（默认 16）
 
 示例配置：
 
@@ -98,7 +99,7 @@ storage_mode = disk
 [upload]
 client_reuse_requests = 0
 max_concurrent = 1
-pool_max_idle_per_host = 1
+pool_max_idle_per_host = 4
 pool_idle_timeout_secs = 300
 ```
 

config.ini.example

@@ -64,6 +64,17 @@ memory_max_file_mb = 100
 # 推荐值: 3-5 (默认值: 3)
 max_concurrent = 3
 
+# 下载与命令通道连接池每主机最大空闲连接数
+# 默认值: 16 (通常足够并能降低常驻内存)
+pool_max_idle_per_host = 16
+
+# 下载连接建立超时（秒）
+connect_timeout_secs = 10
+
+# 下载流式写盘缓冲块大小（KB）
+# 建议保持 256，兼顾吞吐与内存占用
+chunk_size_kb = 256
+
 [upload]
 # 上传客户端复用请求次数 (v1.1.14+)
 # 推荐值: 0
@@ -78,8 +89,8 @@ max_concurrent = 1
 local_file_uri = false
 
 # 上传连接池每主机最大空闲连接数 (v1.1.14+)
-# 推荐值: 1
-pool_max_idle_per_host = 1
+# 推荐值: 4（如需进一步压缩常驻内存可设为 1）
+pool_max_idle_per_host = 4
 
 # 上传连接池空闲超时秒数 (v1.1.14+)
 # 推荐值: 300

src/bot.rs

@@ -37,7 +37,7 @@ pub struct BotState {
     pub download_semaphore: Arc<tokio::sync::Semaphore>,
     pub upload_semaphore: Arc<tokio::sync::Semaphore>,
     pub message_task_semaphore: Arc<tokio::sync::Semaphore>,
-    pub maintenance_tx: tokio::sync::mpsc::UnboundedSender<MaintenanceSignal>,
+    pub maintenance_tx: tokio::sync::mpsc::Sender<MaintenanceSignal>,
     pub bot_username: String,
     pub upload_client_state: Arc<std::sync::Mutex<UploadClientState>>,
     pub maintenance_counters: MaintenanceCounters,
@@ -61,6 +61,7 @@ pub struct UploadCounters {
 }
 
 const SPEED_SAMPLE_WINDOW: usize = 20;
+const MAINTENANCE_QUEUE_CAPACITY: usize = 64;
 
 const MIN_DOWNLOAD_CHUNK_BYTES: usize = 64 * 1024;
 
@@ -468,7 +469,7 @@ pub async fn run(config: Config) -> Result<()> {
     let database = Database::new(&config.database).await?;
     tracing::info!("Database initialized");
 
-    let (maintenance_tx, maintenance_rx) = tokio::sync::mpsc::unbounded_channel();
+    let (maintenance_tx, maintenance_rx) = tokio::sync::mpsc::channel(MAINTENANCE_QUEUE_CAPACITY);
     let maintenance_database = database.clone();
     tokio::spawn(async move {
         maintenance_worker(maintenance_rx, maintenance_database).await;
@@ -489,11 +490,11 @@ pub async fn run(config: Config) -> Result<()> {
                 tracing::info!("Using custom Telegram API URL: {}", api_url);
 
                 // Create a custom HTTP client tuned for Cloudflare compatibility (mimic Go http client)
-                // pool_max_idle_per_host(64) keeps reasonable connection pool for API efficiency
+                let pool_max_idle_per_host = telegram_pool_max_idle_per_host(&config);
                 let client_builder = reqwest::Client::builder()
                     .use_rustls_tls()
                     .user_agent("Go-http-client/2.0")
-                    .pool_max_idle_per_host(64)
+                    .pool_max_idle_per_host(pool_max_idle_per_host)
                     .pool_idle_timeout(std::time::Duration::from_secs(60))
                     .timeout(std::time::Duration::from_secs(30))
                     .no_gzip();
@@ -550,9 +551,10 @@ pub async fn run(config: Config) -> Result<()> {
     } else {
         // 使用默认API URL，但配置连接池以提高效率
         tracing::info!("Using default Telegram API URL: https://api.telegram.org");
+        let pool_max_idle_per_host = telegram_pool_max_idle_per_host(&config);
         let client_builder = reqwest::Client::builder()
             .use_rustls_tls()
-            .pool_max_idle_per_host(64)
+            .pool_max_idle_per_host(pool_max_idle_per_host)
             .pool_idle_timeout(std::time::Duration::from_secs(60))
             .timeout(std::time::Duration::from_secs(30));
         let client = build_reqwest_client(client_builder)?;
@@ -1482,9 +1484,7 @@ async fn download_and_send_music(
     } else {
         state.database.save_song_info(&song_info).await?;
         for signal in collect_maintenance_signals(&state.maintenance_counters, &state.config) {
-            if state.maintenance_tx.send(signal).is_err() {
-                tracing::warn!("Maintenance worker unavailable; skipping signal");
-            }
+            let _ = enqueue_maintenance_signal(&state.maintenance_tx, signal);
         }
     }
 
@@ -1725,6 +1725,23 @@ fn collect_maintenance_signals(
     signals
 }
 
+fn enqueue_maintenance_signal(
+    tx: &tokio::sync::mpsc::Sender<MaintenanceSignal>,
+    signal: MaintenanceSignal,
+) -> bool {
+    match tx.try_send(signal) {
+        Ok(()) => true,
+        Err(tokio::sync::mpsc::error::TrySendError::Full(_)) => {
+            tracing::debug!("Maintenance queue is full; dropping signal {:?}", signal);
+            false
+        }
+        Err(tokio::sync::mpsc::error::TrySendError::Closed(_)) => {
+            tracing::warn!("Maintenance worker unavailable; skipping signal");
+            false
+        }
+    }
+}
+
 async fn join_futures<F1, F2, T1, T2, E>(
     f1: F1,
     f2: F2,
@@ -1750,7 +1767,7 @@ async fn acquire_download_leader(
 }
 
 async fn maintenance_worker(
-    mut rx: tokio::sync::mpsc::UnboundedReceiver<MaintenanceSignal>,
+    mut rx: tokio::sync::mpsc::Receiver<MaintenanceSignal>,
     database: Database,
 ) {
     while let Some(signal) = rx.recv().await {
@@ -1801,6 +1818,10 @@ fn should_set_upload_pool_idle_timeout(secs: u64) -> bool {
     secs > 0
 }
 
+fn telegram_pool_max_idle_per_host(config: &Config) -> usize {
+    config.download_pool_max_idle_per_host.max(1)
+}
+
 fn download_chunk_bytes(config: &Config) -> usize {
     config
         .download_chunk_size_kb
@@ -2686,6 +2707,32 @@ mod tests {
         assert!(super::should_set_upload_pool_idle_timeout(60));
     }
 
+    #[test]
+    fn telegram_pool_uses_configured_download_limit() {
+        let mut config = Config::default();
+        config.download_pool_max_idle_per_host = 7;
+        assert_eq!(super::telegram_pool_max_idle_per_host(&config), 7);
+    }
+
+    #[tokio::test]
+    async fn enqueue_maintenance_signal_drops_when_queue_full() {
+        let (tx, mut rx) = tokio::sync::mpsc::channel(1);
+        assert!(super::enqueue_maintenance_signal(
+            &tx,
+            super::MaintenanceSignal::AnalyzeDb
+        ));
+        assert!(!super::enqueue_maintenance_signal(
+            &tx,
+            super::MaintenanceSignal::ReleaseMemory
+        ));
+
+        assert_eq!(rx.recv().await, Some(super::MaintenanceSignal::AnalyzeDb));
+        assert!(matches!(
+            rx.try_recv(),
+            Err(tokio::sync::mpsc::error::TryRecvError::Empty)
+        ));
+    }
+
     #[test]
     fn download_chunk_bytes_uses_configured_kib() {
         let mut config = Config::default();

src/config.rs

@@ -197,7 +197,7 @@ pub struct Config {
     pub memory_max_file_mb: u64,
     /// Maximum concurrent downloads (lower = less memory, higher = more throughput)
     pub max_concurrent_downloads: u32,
-    /// Max idle connections per host for download client
+    /// Max idle connections per host for download and Telegram command clients
     pub download_pool_max_idle_per_host: usize,
     /// Download connect timeout (seconds)
     pub download_connect_timeout_secs: u64,
@@ -249,14 +249,16 @@ impl Default for Config {
             memory_max_file_mb: 100,
             // Balanced default: slightly higher throughput than 3 with moderate memory growth.
             max_concurrent_downloads: 4,
-            download_pool_max_idle_per_host: 64,
+            // Lower default idle pool cap to reduce steady-state RSS.
+            download_pool_max_idle_per_host: 16,
             download_connect_timeout_secs: 10,
             download_chunk_size_kb: 256,
             cover_mode: CoverMode::Thumbnail,
             upload_client_reuse_requests: 0,
             upload_max_concurrent: 1,
             upload_log_level: UploadLogLevel::default(),
-            upload_pool_max_idle_per_host: 64,
+            // Upload traffic is usually single-stream; keep a small idle pool.
+            upload_pool_max_idle_per_host: 4,
             upload_pool_idle_timeout_secs: 300,
             upload_timeout_secs: 300,
             upload_local_file_uri: false,
@@ -509,7 +511,7 @@ mod tests {
     #[test]
     fn download_pool_defaults_are_tunable() {
         let config = Config::default();
-        assert!(config.download_pool_max_idle_per_host > 0);
+        assert_eq!(config.download_pool_max_idle_per_host, 16);
         assert!(config.download_connect_timeout_secs > 0);
     }
 
@@ -530,7 +532,7 @@ mod tests {
         let config = Config::default();
         assert_eq!(config.upload_client_reuse_requests, 0);
         assert_eq!(config.upload_max_concurrent, 1);
-        assert_eq!(config.upload_pool_max_idle_per_host, 64);
+        assert_eq!(config.upload_pool_max_idle_per_host, 4);
         assert_eq!(config.upload_pool_idle_timeout_secs, 300);
         assert_eq!(config.upload_timeout_secs, 300);
     }