[router] add health checking in router init (#2393)

rust/Cargo.lock

@@ -851,6 +851,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2dff15bf788c671c1934e366d07e30c1814a8ef514e1af724a602e8a2fbe1b10"
 dependencies = [
  "futures-core",
+ "futures-sink",
 ]
 
 [[package]]
@@ -1986,6 +1987,7 @@ dependencies = [
  "base64 0.22.1",
  "bytes",
  "encoding_rs",
+ "futures-channel",
  "futures-core",
  "futures-util",
  "h2 0.4.6",

rust/Cargo.toml

@@ -19,7 +19,7 @@ serde = { version = "1.0", features = ["derive"] }
 clap = { version = "4.4", features = ["derive"] }
 bytes = "1.8.0"
 rand = "0.8.5"
-reqwest = { version = "0.12.8", features = ["stream"] }
+reqwest = { version = "0.12.8", features = ["stream", "blocking"] }
 futures-util = "0.3"
 serde_json = "1.0"
 pyo3 = { version = "0.22.5", features = ["extension-module"] }

rust/py_src/sglang_router/launch_server.py

@@ -167,13 +167,6 @@ def main():
         signal.SIGQUIT, lambda sig, frame: cleanup_processes(server_processes)
     )
 
-    for port in worker_ports:
-        if not wait_for_server_health(server_args.host, port):
-            logger.error(f"Server on port {port} failed to become healthy")
-            break
-
-    logger.info("All servers are healthy. Starting router...")
-
     # Update router args with worker URLs
     router_args.worker_urls = [
         f"http://{server_args.host}:{port}" for port in worker_ports

rust/src/router.rs

@@ -93,7 +93,7 @@ pub enum Router {
     },
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub enum PolicyConfig {
     RandomConfig,
     RoundRobinConfig,
@@ -127,9 +127,14 @@ fn get_text_from_request(body: &Bytes, route: &str) -> String {
 
     return "".to_string();
 }
+
 impl Router {
-    pub fn new(worker_urls: Vec<String>, policy_config: PolicyConfig) -> Self {
+    pub fn new(worker_urls: Vec<String>, policy_config: PolicyConfig) -> Result<Self, String> {
-        match policy_config {
+        // Wait until all workers are healthy
+        Self::wait_for_healthy_workers(&worker_urls, 300, 10)?;
+
+        // Create router based on policy...
+        Ok(match policy_config {
             PolicyConfig::RandomConfig => Router::Random {
                 worker_urls: Arc::new(RwLock::new(worker_urls)),
             },
@@ -196,7 +201,7 @@ impl Router {
                     _eviction_thread: Some(eviction_thread),
                 }
             }
-        }
+        })
     }
 
     pub fn get_first(&self) -> Option<String> {
@@ -213,6 +218,59 @@ impl Router {
         }
     }
 
+    fn wait_for_healthy_workers(
+        worker_urls: &[String],
+        timeout_secs: u64,
+        interval_secs: u64,
+    ) -> Result<(), String> {
+        let start_time = std::time::Instant::now();
+        let sync_client = reqwest::blocking::Client::new();
+
+        loop {
+            if start_time.elapsed() > Duration::from_secs(timeout_secs) {
+                return Err(format!(
+                    "Timeout {}s waiting for workers to become healthy",
+                    timeout_secs
+                ));
+            }
+
+            let mut all_healthy = true;
+            let mut unhealthy_workers = Vec::new();
+
+            for url in worker_urls {
+                match sync_client.get(&format!("{}/health", url)).send() {
+                    Ok(res) => {
+                        if !res.status().is_success() {
+                            info!(
+                                "Worker {} health check is pending with status: {}.",
+                                url,
+                                res.status()
+                            );
+                            all_healthy = false;
+                            unhealthy_workers.push((url, format!("Status: {}", res.status())));
+                        }
+                    }
+                    Err(e) => {
+                        info!("Worker {} health check is pending with error: {}", url, e);
+                        all_healthy = false;
+                        unhealthy_workers.push((url, format!("Error: {}", e)));
+                    }
+                }
+            }
+
+            if all_healthy {
+                info!("All workers are healthy");
+                return Ok(());
+            } else {
+                info!("Unhealthy workers:");
+                for (url, reason) in &unhealthy_workers {
+                    info!("  {} - {}", url, reason);
+                }
+                thread::sleep(Duration::from_secs(interval_secs));
+            }
+        }
+    }
+
     pub async fn dispatch(
         &self,
         client: &reqwest::Client,
@@ -386,7 +444,7 @@ impl Router {
         }
     }
 
-    pub async fn add_worker(&self, worker_url: String) -> HttpResponse {
+    pub async fn add_worker(&self, worker_url: String) -> Result<String, String> {
         let interval_secs = 10; // check every 10 seconds
         let timeout_secs = 300; // 5 minutes
 
@@ -395,7 +453,7 @@ impl Router {
 
         loop {
             if start_time.elapsed() > Duration::from_secs(timeout_secs) {
-                return HttpResponse::InternalServerError().body(format!(
+                return Err(format!(
                     "Timeout {}s waiting for worker {} to become healthy",
                     timeout_secs, worker_url
                 ));
@@ -411,19 +469,40 @@ impl Router {
                                 info!("Worker {} health check passed", worker_url);
                                 let mut urls = worker_urls.write().unwrap();
                                 if urls.contains(&worker_url) {
-                                    return HttpResponse::BadRequest()
+                                    return Err(format!("Worker {} already exists", worker_url));
-                                        .body(format!("Worker {} already exists", worker_url));
                                 }
                                 info!("Added worker: {}", worker_url);
                                 urls.push(worker_url.clone());
                             }
                         }
-                        return HttpResponse::Ok()
+
-                            .body(format!("Successfully added worker: {}", worker_url));
+                        // If cache aware, initialize the queues for the new worker
+                        if let Router::CacheAware {
+                            running_queue,
+                            processed_queue,
+                            tree,
+                            ..
+                        } = self
+                        {
+                            // Add worker to running queue with initial count of 0
+                            running_queue.lock().unwrap().insert(worker_url.clone(), 0);
+
+                            // Add worker to processed queue with initial count of 0
+                            processed_queue
+                                .lock()
+                                .unwrap()
+                                .insert(worker_url.clone(), 0);
+
+                            // Add worker to tree
+                            tree.lock().unwrap().insert(&"".to_string(), &worker_url);
+                        }
+
+                        return Ok(format!("Successfully added worker: {}", worker_url));
                     } else {
                         info!(
-                            "Worker {} health check failed with status: {}. The worker might still be starting up.",
+                            "Worker {} health check is pending with status: {}.",
-                            worker_url, res.status()
+                            worker_url,
+                            res.status()
                         );
                         // if the url does not have http or https prefix, warn users
                         if !worker_url.starts_with("http://") && !worker_url.starts_with("https://")
@@ -436,7 +515,10 @@ impl Router {
                     }
                 }
                 Err(e) => {
-                    info!("Worker {} health check failed: {}", worker_url, e);
+                    info!(
+                        "Worker {} health check is pending with error: {}",
+                        worker_url, e
+                    );
 
                     // if the url does not have http or https prefix, warn users
                     if !worker_url.starts_with("http://") && !worker_url.starts_with("https://") {
@@ -463,9 +545,20 @@ impl Router {
         }
 
         // if cache aware, remove the worker from the tree
-        if let Router::CacheAware { tree, .. } = self {
+        if let Router::CacheAware {
+            tree,
+            running_queue,
+            processed_queue,
+            ..
+        } = self
+        {
             tree.lock().unwrap().remove_tenant(&worker_url);
-            info!("Removed worker from tree: {}", worker_url);
+            running_queue.lock().unwrap().remove(&worker_url);
+            processed_queue.lock().unwrap().remove(&worker_url);
+            info!(
+                "Removed worker from tree and cleaned up queues: {}",
+                worker_url
+            );
         }
     }
 }

rust/src/server.rs

@@ -20,7 +20,10 @@ impl AppState {
         policy_config: PolicyConfig,
     ) -> Self {
         // Create router based on policy
-        let router = Router::new(worker_urls, policy_config);
+        let router = match Router::new(worker_urls, policy_config) {
+            Ok(router) => router,
+            Err(error) => panic!("Failed to create router: {}", error),
+        };
 
         Self { router, client }
     }
@@ -141,7 +144,11 @@ async fn add_worker(
                 .body("Worker URL required. Provide 'url' query parameter")
         }
     };
-    data.router.add_worker(worker_url).await
+
+    match data.router.add_worker(worker_url).await {
+        Ok(message) => HttpResponse::Ok().body(message),
+        Err(error) => HttpResponse::BadRequest().body(error),
+    }
 }
 
 #[post("/remove_worker")]
@@ -187,20 +194,20 @@ pub async fn startup(config: ServerConfig) -> std::io::Result<()> {
         )
         .init();
 
-    info!("Starting server on {}:{}", config.host, config.port);
-    info!("Worker URLs: {:?}", config.worker_urls);
-    info!("Policy Config: {:?}", config.policy_config);
-
     let client = reqwest::Client::builder()
         .build()
         .expect("Failed to create HTTP client");
 
     let app_state = web::Data::new(AppState::new(
-        config.worker_urls,
+        config.worker_urls.clone(),
         client,
-        config.policy_config,
+        config.policy_config.clone(),
     ));
 
+    info!("✅ Starting router on {}:{}", config.host, config.port);
+    info!("✅ Serving Worker URLs: {:?}", config.worker_urls);
+    info!("✅ Policy Config: {:?}", config.policy_config);
+
     HttpServer::new(move || {
         App::new()
             .app_data(app_state.clone())