Added new compat flag for queue consumers and waitUntil (#20952)

* Added new compat flag for queue consumers and waitUntil

* Update src/content/compatibility-flags/queue-consumer-no-wait-waituntil.md

Co-authored-by: hyperlint-ai[bot] <154288675+hyperlint-ai[bot]@users.noreply.github.com>

* Update src/content/compatibility-flags/queue-consumer-no-wait-waituntil.md

Co-authored-by: hyperlint-ai[bot] <154288675+hyperlint-ai[bot]@users.noreply.github.com>

* Update src/content/compatibility-flags/queue-consumer-no-wait-waituntil.md

Co-authored-by: hyperlint-ai[bot] <154288675+hyperlint-ai[bot]@users.noreply.github.com>

* Update src/content/compatibility-flags/queue-consumer-no-wait-waituntil.md

Co-authored-by: hyperlint-ai[bot] <154288675+hyperlint-ai[bot]@users.noreply.github.com>

* Update src/content/compatibility-flags/queue-consumer-no-wait-waituntil.md

Co-authored-by: Jun Lee <[email protected]>

* Apply suggestions from code review

Co-authored-by: Jun Lee <[email protected]>

* Update src/content/compatibility-flags/queue-consumer-no-wait-waituntil.md

Co-authored-by: Greg Brimble <[email protected]>

---------

Co-authored-by: hyperlint-ai[bot] <154288675+hyperlint-ai[bot]@users.noreply.github.com>
Co-authored-by: Jun Lee <[email protected]>
Co-authored-by: Greg Brimble <[email protected]>

Author: 4 people

src/content/compatibility-flags/queue-consumer-no-wait-waituntil.md

@@ -0,0 +1,38 @@
+---
+_build:
+  publishResources: false
+  render: never
+  list: never
+
+name: "Queue consumers don't wait for `ctx.waitUntil()` to resolve"
+sort_date: "2025-03-19"
+experimental: true
+enable_flag: "queue_consumer_no_wait_for_wait_until"
+---
+
+By default, [Queues](/queues/) Consumer Workers acknowledge messages only after promises passed to [`ctx.waitUntil()`](/workers/runtime-apis/context) have resolved. This behavior can cause queue consumers which utilize `ctx.waitUntil()` to process messages slowly. The default behavior is documented in the [Queues Consumer Configuration Guide](/queues/configuration/javascript-apis#consumer).
+
+This Consumer Worker is an example of a Worker which utilizes `ctx.waitUntil()`. Under the default behavior, this consumer Worker will only acknowledge a batch of messages after the sleep function has resolved.
+```js
+export default {
+  async fetch(request, env, ctx) {
+    // omitted
+  },
+
+  async queue(batch, env, ctx) {
+    console.log(`received batch of ${batch.messages.length} messages to queue ${batch.queue}`);
+    for (let i = 0; i < batch.messages.length; ++i) {
+      console.log(`message #${i}: ${JSON.stringify(batch.messages[i])}`);
+    }
+    ctx.waitUntil(sleep(30 * 1000));
+  }
+};
+
+function sleep(ms) {
+  return new Promise(resolve => setTimeout(resolve, ms));
+}
+```
+
+If the `queue_consumer_no_wait_for_wait_until` flag is enabled, Queues consumers will no longer wait for promises passed to `ctx.waitUntil()` to resolve before acknowledging messages. This can improve the performance of queue consumers which utilize `ctx.waitUntil()`. With the flag enabled, in the above example, the consumer Worker will acknowledge the batch without waiting for the sleep function to resolve.
+
+Using this flag will not affect the behavior of `ctx.waitUntil()`. `ctx.waitUntil()` will continue to extend the lifetime of your consumer Worker to continue to work even after the batch of messages has been acknowledged.