perf: Avoid loading unused services (#12537)

* fix: Run single process when only the worker service is enabled

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* perf: Improve memory consumption through lazy service loading

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

server/index.ts

@@ -184,8 +184,8 @@ async function start(_id: number, disconnect: () => void) {
     }
 
     Logger.info("lifecycle", `Starting ${name} service`);
-    const init = services[name as keyof typeof services];
-    await init(app, server as https.Server, env.SERVICES);
+    const { default: init } = await services[name as keyof typeof services]();
+    await Promise.resolve(init(app, server as https.Server, env.SERVICES));
   }
 
   server.on("error", (err) => {
@@ -258,8 +258,11 @@ const isWebProcess =
   env.SERVICES.includes("api") ||
   env.SERVICES.includes("collaboration");
 
+const isWorkerProcess =
+  env.SERVICES.length === 1 && env.SERVICES.includes("worker");
+
 void throng({
   master,
   worker: start,
-  count: isWebProcess ? webProcessCount : undefined,
+  count: isWorkerProcess ? 1 : isWebProcess ? webProcessCount : undefined,
 });

server/services/index.ts

@@ -1,15 +1,16 @@
-import admin from "./admin";
-import collaboration from "./collaboration";
-import cron from "./cron";
-import web from "./web";
-import websockets from "./websockets";
-import worker from "./worker";
-
-export default {
-  websockets,
-  collaboration,
-  admin,
-  web,
-  worker,
-  cron,
+/**
+ * Services are lazily imported so that only the modules for the services
+ * actually being run are loaded into memory. For example, a worker-only
+ * process does not need to import the web or collaboration services and their
+ * (often heavy) dependency trees.
+ */
+const services = {
+  websockets: () => import("./websockets"),
+  collaboration: () => import("./collaboration"),
+  admin: () => import("./admin"),
+  web: () => import("./web"),
+  worker: () => import("./worker"),
+  cron: () => import("./cron"),
 } as const;
+
+export default services;