fix(dev-server): Terminate turbopack HMR websocket connections during…

… exit (#75344) Without this change, an open browser tab with an HMR websocket subscription (which is very common) can prevent next.js's dev server from exiting cleanly (falls back to a SIGKILL after a 100ms timeout). That's bad (aside from the extra 100ms delay) because it prevents ``` await Promise.all([ nextServer?.close().catch(console.error), cleanupListeners?.runAll().catch(console.error), ]) ``` from running, which can prevent us from flushing task statistics (#67164). You can test this with: ``` NEXT_EXIT_TIMEOUT_MS=200000 node_modules/.bin/next dev ``` or ``` NEXT_EXIT_TIMEOUT_MS=200000 node_modules/.bin/next dev --turbo ``` Prior to this PR, after hitting ctrl+c, the processes will hang if there's a connected browser window open. After this PR, the processes exit instantly.
vercel · Jan 30, 2025 · 0f7251f · 0f7251f
1 parent 28ac628
commit 0f7251f
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Showing 8 changed files with 44 additions and 15 deletions.
diff --git a/packages/next/src/server/dev/hot-middleware.ts b/packages/next/src/server/dev/hot-middleware.ts
@@ -72,16 +72,11 @@ class EventStream {
     this.clients = new Set()
   }
 
-  everyClient(fn: (client: ws) => void) {
-    for (const client of this.clients) {
-      fn(client)
-    }
-  }
-
   close() {
-    this.everyClient((client) => {
-      client.close()
-    })
+    for (const wsClient of this.clients) {
+      // it's okay to not cleanly close these websocket connections, this is dev
+      wsClient.terminate()
+    }
     this.clients.clear()
   }
 
@@ -93,9 +88,9 @@ class EventStream {
   }
 
   publish(payload: any) {
-    this.everyClient((client) => {
-      client.send(JSON.stringify(payload))
-    })
+    for (const wsClient of this.clients) {
+      wsClient.send(JSON.stringify(payload))
+    }
   }
 }
 

diff --git a/packages/next/src/server/dev/hot-reloader-turbopack.ts b/packages/next/src/server/dev/hot-reloader-turbopack.ts
@@ -1059,6 +1059,13 @@ export async function createHotReloaderTurbopack(
           }
         })
     },
+    close() {
+      for (const wsClient of clients) {
+        // it's okay to not cleanly close these websocket connections, this is dev
+        wsClient.terminate()
+      }
+      clients.clear()
+    },
   }
 
   handleEntrypointsSubscription().catch((err) => {

diff --git a/packages/next/src/server/dev/hot-reloader-types.ts b/packages/next/src/server/dev/hot-reloader-types.ts
@@ -182,4 +182,5 @@ export interface NextJsHotReloaderInterface {
     definition: RouteDefinition | undefined
     url?: string
   }): Promise<void>
+  close(): void
 }
diff --git a/packages/next/src/server/dev/hot-reloader-webpack.ts b/packages/next/src/server/dev/hot-reloader-webpack.ts
@@ -1595,4 +1595,8 @@ export default class HotReloaderWebpack implements NextJsHotReloaderInterface {
         })
       })
   }
+
+  public close() {
+    this.webpackHotMiddleware?.close()
+  }
 }
diff --git a/packages/next/src/server/lib/dev-bundler-service.ts b/packages/next/src/server/lib/dev-bundler-service.ts
@@ -103,4 +103,8 @@ export class DevBundlerService {
       data: this.appIsrManifest,
     })
   }
+
+  public close() {
+    this.bundler.hotReloader.close()
+  }
 }
diff --git a/packages/next/src/server/lib/render-server.ts b/packages/next/src/server/lib/render-server.ts
@@ -9,6 +9,8 @@ export type ServerInitResult = {
   requestHandler: RequestHandler
   upgradeHandler: UpgradeHandler
   server: NextServer
+  // Make an effort to close upgraded HTTP requests (e.g. Turbopack HMR websockets)
+  closeUpgraded: () => void
 }
 
 let initializations: Record<string, Promise<ServerInitResult> | undefined> = {}
@@ -109,6 +111,9 @@ async function initializeImpl(opts: {
     requestHandler,
     upgradeHandler,
     server,
+    closeUpgraded() {
+      opts.bundlerService?.close()
+    },
   }
 }
 

diff --git a/packages/next/src/server/lib/router-server.ts b/packages/next/src/server/lib/router-server.ts
@@ -751,5 +751,12 @@ export async function initialize(opts: {
     }
   }
 
-  return { requestHandler, upgradeHandler, server: handlers.server }
+  return {
+    requestHandler,
+    upgradeHandler,
+    server: handlers.server,
+    closeUpgraded() {
+      developmentBundler?.hotReloader?.close()
+    },
+  }
 }
diff --git a/packages/next/src/server/lib/start-server.ts b/packages/next/src/server/lib/start-server.ts
@@ -289,6 +289,7 @@ export async function startServer(
 
       try {
         let cleanupStarted = false
+        let closeUpgraded: (() => void) | null = null
         const cleanup = () => {
           if (cleanupStarted) {
             // We can get duplicate signals, e.g. when `ctrl+c` is used in an
@@ -303,12 +304,16 @@ export async function startServer(
 
             // first, stop accepting new connections and finish pending requests,
             // because they might affect `nextServer.close()` (e.g. by scheduling an `after`)
-            await new Promise<void>((res) =>
+            await new Promise<void>((res) => {
               server.close((err) => {
                 if (err) console.error(err)
                 res()
               })
-            )
+              if (isDev) {
+                server.closeAllConnections()
+                closeUpgraded?.()
+              }
+            })
 
             // now that no new requests can come in, clean up the rest
             await Promise.all([
@@ -360,6 +365,7 @@ export async function startServer(
         requestHandler = initResult.requestHandler
         upgradeHandler = initResult.upgradeHandler
         nextServer = initResult.server
+        closeUpgraded = initResult.closeUpgraded
 
         const startServerProcessDuration =
           performance.mark('next-start-end') &&
-Original file line number
+Diff line change
@@ Expand Up @@
             })
           })
       }
+      public close() {
+        this.webpackHotMiddleware?.close()
+      }
     }