feat: limit the number of connections open in Node.js (#271)

package.json

@@ -92,7 +92,7 @@
   },
   "dependencies": {
     "@sanity/eventsource": "^5.0.0",
-    "get-it": "^8.2.0",
+    "get-it": "^8.3.0",
     "rxjs": "^7.0.0"
   },
   "devDependencies": {

src/http/nodeMiddleware.ts

@@ -1,10 +1,24 @@
-import {debug, headers} from 'get-it/middleware'
+import {agent, debug, headers} from 'get-it/middleware'
 
 import {name, version} from '../../package.json'
 
 const middleware = [
   debug({verbose: true, namespace: 'sanity:client'}),
   headers({'User-Agent': `${name} ${version}`}),
+
+  // Enable keep-alive, and in addition limit the number of sockets that can be opened.
+  // This avoids opening too many connections to the server if someone tries to execute
+  // a bunch of requests in parallel. It's recommended to have a concurrency limit
+  // at a "higher limit" (i.e. you shouldn't actually execute hundreds of requests in parallel),
+  // and this is mainly to minimize the impact for the network and server.
+  //
+  // We're currently matching the same defaults as browsers:
+  // https://stackoverflow.com/questions/26003756/is-there-a-limit-practical-or-otherwise-to-the-number-of-web-sockets-a-page-op
+  agent({
+    keepAlive: true,
+    maxSockets: 30,
+    maxTotalSockets: 256,
+  }),
 ]
 
 export default middleware