Add a Redis PING every minute to keep the connection alive (#18584)

* Add a Redis PING every minute to keep the connection alive

Author: JamesMGreene

lib/redis/create-client.js

@@ -34,6 +34,14 @@ module.exports = function createClient (options = {}) {
     }
   }
 
+  let pingInterval = null
+  function stopPinging () {
+    if (pingInterval) {
+      clearInterval(pingInterval)
+      pingInterval = null
+    }
+  }
+
   // Create the client
   const client = Redis.createClient(url, {
     // Only add this configuration for TLS-enabled Redis URL values.
@@ -96,6 +104,26 @@ module.exports = function createClient (options = {}) {
     } catch (disconnectError) {
       // Swallow any failure
     }
+
+    // Also, stop pinging the Redis server
+    stopPinging()
+  })
+
+  client.on('connect', () => {
+    // Stop pinging the Redis server, if any such timer already exists
+    stopPinging()
+
+    // Start pinging the server once per minute to prevent Redis connection
+    // from closing when its idle `timeout` configuration value expires
+    pingInterval = setInterval(
+      () => { client.ping(() => {}) },
+      60 * 1000
+    )
+  })
+
+  client.on('end', () => {
+    // Stop pinging the Redis server
+    stopPinging()
   })
 
   // If a `name` was provided, use it in the prefix for logging event messages