https://e-mahmoudi.me/tags/concurrency/Recent content in Concurrency on Ehsan Mahmoudi — Blockchain Consultant & Software Architect | Hire RemoteHugoen-usSun, 21 Jun 2026 00:00:00 +0000https://e-mahmoudi.me/blog/a-small-fintech-challenge-and-why-i-let-postgres-hold-the-money/Sun, 21 Jun 2026 00:00:00 +0000https://e-mahmoudi.me/blog/a-small-fintech-challenge-and-why-i-let-postgres-hold-the-money/<h1 id="a-small-fintech-challenge-and-why-i-let-postgres-hold-the-money">A Small Fintech Challenge, and Why I Let Postgres Hold the Money</h1> <p>I picked up a small backend challenge recently: build a marketplace where guilds buy and auction items using in-game gold. Listings, auctions, bids, a price oracle, automatic settlement. On the surface it&rsquo;s a CRUD app.</p> <p>The full source is on GitHub: <a href="https://github.com/jeyem/dragon-market">github.com/jeyem/dragon-market</a>.</p> <p>It isn&rsquo;t. The moment money moves and two people act at the same time, it becomes the only problem that matters:</p>