Run slow work as a background job

Problem

A report, import, or media conversion takes too long for one request and becomes fragile behind browser, proxy, or deployment timeouts.

Before you start

Give the job a durable ID, owner, state, progress value, and expiry policy. Make starting the same job twice safe when duplicate work would be expensive.

Start the job, then ask for status

<section>
  <form ng-post="/api/exports" on-success="job = $res">
    <label>
      Format
      <select name="format"><option value="csv">CSV</option></select>
    </label>
    <button type="submit">Create export</button>
  </form>
  <div ng-if="job">
    <p>Status: {{ job.status }}</p>
    <button
      type="button"
      ng-get="/api/exports/current"
      on-success="job = $res"
    >
      Refresh status
    </button>
    <a ng-if="job.downloadUrl" href="{{ job.downloadUrl }}">Download</a>
  </div>
</section>

Use manual refresh first. Add measured polling or server-sent events only when the user benefits from continuous progress.

Server contract

Return 202 with the accepted job representation. The status endpoint returns queued, running, completed, failed, or cancelled. Authorize status and download URLs against the job owner on every request.

Failure path

Keep a failed job record with a safe explanation and request ID. Do not expose worker stack traces or leave failed uploads and generated files indefinitely.

Apply it now

Find the longest request in production traces. Move it to a job when its work can continue independently of the browser connection.

Verify

Test duplicate starts, worker restart, cancellation, failure, expiry, another user’s job ID, and download after completion.