demonstrate async cleanup in graceful shutdowns

examples/complex.js

@@ -19,10 +19,12 @@ function worker(id, disconnect) {
   process.on('SIGTERM', shutdown)
   process.on('SIGINT', shutdown)
 
-  function shutdown() {
+  async function shutdown() {
     if (exited) return
     exited = true
-    console.log(`Worker ${ id } cleanup.`)
+
+    await new Promise(r => setTimeout(r, 300))  // simulate async cleanup work
+    console.log(`Worker ${ id } cleanup done.`)
     disconnect()
   }
 }

readme.md

@@ -103,12 +103,18 @@ function master() {
 
 // This will be called four times
 function worker(id, disconnect) {
+  let exited = false
+
   console.log(`Started worker ${ id }`)
   process.on('SIGTERM', shutdown)
   process.on('SIGINT', shutdown)
 
-  function shutdown() {
-    console.log(`Worker ${ id } cleanup.`)
+  async function shutdown() {
+    if (exited) return
+    exited = true
+
+    await new Promise(r => setTimeout(r, 300))  // simulate async cleanup work
+    console.log(`Worker ${ id } cleanup done.`)
     disconnect()
   }
 }
@@ -122,10 +128,10 @@ Started worker 3
 Started worker 2
 Started worker 4
 ^C
-Worker 1 cleanup.
-Worker 3 cleanup.
-Worker 2 cleanup.
-Worker 4 cleanup.
+Worker 1 cleanup done.
+Worker 3 cleanup done.
+Worker 2 cleanup done.
+Worker 4 cleanup done.
 Master cleanup.
 ```
 

test/fixtures/graceful-sigusr2.js

@@ -1,17 +1,18 @@
-'use strict';
-
-const throng = require('../../lib/throng');
+const throng = require('../../lib/throng')
 
 throng({
     workers: 3,
     signals: ['SIGUSR2'],
     start: (id, disconnect) => {
-        console.log('worker');
-
-        process.on('SIGUSR2', exit);
+        let exited = false
+
+        console.log('worker')
+        process.on('SIGUSR2', exit)
 
         function exit() {
-          console.log(`exiting`);
+          if (exited) return
+          exited = true
+          console.log(`exiting`)
           disconnect()
         }
     }

test/fixtures/graceful.js

@@ -1,19 +1,18 @@
-'use strict';
-
-const throng = require('../../lib/throng');
+const throng = require('../../lib/throng')
 
 throng(3, (id, disconnect) => {
   let exited = false
 
-  console.log('worker');
-
+  console.log('worker')
   process.on('SIGTERM', exit)
   process.on('SIGINT', exit)
 
   async function exit() {
     if (exited) return
     exited = true
+
+    await new Promise(r => setTimeout(r, 100))  // simulate async cleanup
     console.log('exiting')
     disconnect()
   }
-});
+})