https://nalar.dev/tags/sync/ Recent content in Sync on Nalar Hugo en-us Wed, 02 Sep 2026 00:00:00 +0700 https://nalar.dev/lazy-initialization-with-sync-oncevalue-and-oncevalues/ Wed, 02 Sep 2026 00:00:00 +0700 https://nalar.dev/lazy-initialization-with-sync-oncevalue-and-oncevalues/ <p>Lazy initialization is useful when a value is expensive to build and may never be needed. The difficulty is making that initialization safe when several goroutines request the value at the same time.</p> <p>Go has long provided <code>sync.Once</code>. Since Go 1.21, the <code>sync</code> package also includes <code>OnceValue</code> and <code>OnceValues</code>, helpers that return functions which compute results once and reuse them for later calls.</p> <h2 id="the-manual-synconce-pattern">The manual <code>sync.Once</code> pattern</h2> <p>A classic implementation looks like this:</p>