Designing a Distributed Job Scheduler That Runs Jobs Exactly Once

<p>You add a recurring job to a Node.js service. It works on your laptop. Then you deploy three replicas, and all three run the job.</p> <p>Each process has its own timer. Without

<p>Failures are a normal and expected part of distributed systems.</p> <p>If your application processes data asynchronously—for example, by consuming messages from Kafka or

<p><code>@Scheduled</code> is fine until it isn't. It runs in one JVM, so the moment you scale to two instances the<br /> job fires twice. It has no retry, no timeout, no record

<blockquote> <p>The pager went off at 2:14 AM.</p> </blockquote> <p>If you’ve spent any time operating distributed systems, you know that sound. It doesn’t just wake you up; it

<p>Short answer: for a scheduled daily report email backend, use cron to start one coordinator, then put one durable, idempotent delivery job per subscriber behind it; direct