https://drewg3r.dev/posts/ Recent content in Posts on Andrii T. – Software Engineer Hugo en Sun, 27 Jul 2025 12:00:00 +0000 https://drewg3r.dev/posts/dont-let-failed-tasks-stop-chord-callback/ Sun, 27 Jul 2025 12:00:00 +0000 https://drewg3r.dev/posts/dont-let-failed-tasks-stop-chord-callback/ <h2 class="heading" id="the-problem"> The problem <a class="anchor" href="#the-problem">#</a> </h2> <p>Let’s start with a simplified real-world scenario: you need to process a large number of contracts in parallel, and once they&rsquo;re done, generate a report. The reporting task analyzes the outcome of each contract, generates some fancy charts for management and sends them via email.</p> <p>So, the workflow looks like this:</p> <ol> <li>Schedule one task per contract and wait for them all to complete.</li> <li>Run a report task that aggregates the results and performs the analysis.</li> </ol> <p>If you’re familiar with <a href="https://docs.celeryq.dev/">Celery</a>, this may sound like a perfect use case for a <code>chord</code>: run multiple tasks in parallel (the <em>header</em>), then execute a <em>callback</em> once they all finish.</p>