Enable cluster mode in NodeJS as Heroku suggested

ecosystem.config.js

@@ -13,6 +13,9 @@ module.exports = {
       autorestart: true,
       watch: false,
       max_memory_restart: `${process.env.WEB_MEMORY || 512}M`, // // Auto-restart if process takes more than XXmo
+
+      // https://devcenter.heroku.com/articles/optimizing-dyno-usage#node-js
+      exec_mode: 'cluster',
     },
   ],
 };

src/index.js

@@ -282,3 +282,15 @@ async function processText(
   console.log('\n||LOG||---------->');
   return result;
 }
+
+// Graceful shutdown
+// https://pm2.keymetrics.io/docs/usage/cluster-mode/#graceful-shutdown
+process.on('SIGINT', async () => {
+  try {
+    await redis.quit();
+    process.exit(0);
+  } catch (e) {
+    console.error(e);
+    process.exit(1);
+  }
+});

src/redisClient.js

@@ -55,8 +55,21 @@ function del(key) {
   });
 }
 
+function quit() {
+  return new Promise((resolve, reject) => {
+    client.quit(err => {
+      if (err) {
+        reject(err);
+      } else {
+        resolve();
+      }
+    });
+  });
+}
+
 export default {
   set,
   get,
   del,
+  quit,
 };