perf: Reuse redis connections where possible (#1157)

* reuse redis connections where possible

* redis -> ioredis

server/utils/queue.js

@@ -0,0 +1,19 @@
+// @flow
+import Redis from 'ioredis';
+import Queue from 'bull';
+import { client, subscriber } from '../redis';
+
+export function createQueue(name: string) {
+  return new Queue(name, {
+    createClient(type) {
+      switch (type) {
+        case 'client':
+          return client;
+        case 'subscriber':
+          return subscriber;
+        default:
+          return new Redis(process.env.REDIS_URL);
+      }
+    },
+  });
+}