Durable Objects - Outbound connections keep Durable Objects alive

<p>Durable Objects now remain alive for the duration of active outbound connections created via <a href="https://developers.cloudflare.com/workers/runtime-apis/tcp-sockets/"><code>connect()</code></a> or an outbound WebSocket. Previously, a Durable Object would be evicted after 70-140 seconds of no incoming traffic, even if the object had an open outbound connection, which is a common pattern when streaming responses from a large language model (LLM) over TCP or an outbound WebSocket.</p> <p>With this change, each active outbound connection prevents eviction. Once all outbound connections close, the standard 70-140 second inactivity window applies before the Durable Object is evicted.</p> <div tabindex="-1" class="heading-wrapper level-h4"><h4 id="before-streaming-connections-were-cut-off-by-eviction">Before: streaming connections were cut off by eviction</h4><a class="anchor-link" href="#before-streaming-connections-were-cut-off-by-eviction"><span aria-hidden="true" class="anchor-icon"><svg width="16" height="16" viewBox="0 0 24 24"><path fill="currentcolor" d="m12.11 15.39-3.88 3.88a2.52 2.52 0 0 1-3.5 0 2.47 2.47 0 0 1 0-3.5l3.88-3.88a1 1 0 0 0-1.42-1.42l-3.88 3.89a4.48 4.48 0 0 0 6.33 6.33l3.89-3.88a1 1 0 1 0-1.42-1.42Zm8.58-12.08a4.49 4.49 0 0 0-6.33 0l-3.89 3.88a1 1 0 0 0 1.42 1.42l3.88-3.88a2.52 2.52 0 0 1 3.5 0 2.47 2.47 0 0 1 0 3.5l-3.88 3.88a1 1 0 1 0 1.42 1.42l3.88-3.89a4.49 4.49 0 0 0 0-6.33ZM8.83 15.17a1 1 0 0 0 1.1.22 1 1 0 0 0 .32-.22l4.92-4.92a1 1 0 0 0-1.42-1.42l-4.92 4.92a1 1 0 0 0 0 1.42Z"></path></svg></span></a></div> <img src="https://developers.cloudflare.com/cdn-cgi/image/onerror=redirect,width=820,height=360,format=svg/_astro/outbound-connection-before.jZgN3tY3.svg" alt="Timeline showing a Durable Object evicted 70-140 seconds after the last incoming request, cutting off an in-flight LLM stream while the outbound connection is still open" loading="lazy" decoding="async" width="820" height="360"> <div tabindex="-1" class="heading-wrapper level-h4"><h4 id="after-active-outbound-connections-keep-the-durable-object-alive">After: active outbound connections keep the Durable Object alive</h4><a class="anchor-link" href="#after-active-outbound-connections-keep-the-durable-object-alive"><span aria-hidden="true" class="anchor-icon"><svg width="16" height="16" viewBox="0 0 24 24"><path fill="currentcolor" d="m12.11 15.39-3.88 3.88a2.52 2.52 0 0 1-3.5 0 2.47 2.47 0 0 1 0-3.5l3.88-3.88a1 1 0 0 0-1.42-1.42l-3.88 3.89a4.48 4.48 0 0 0 6.33 6.33l3.89-3.88a1 1 0 1 0-1.42-1.42Zm8.58-12.08a4.49 4.49 0 0 0-6.33 0l-3.89 3.88a1 1 0 0 0 1.42 1.42l3.88-3.88a2.52 2.52 0 0 1 3.5 0 2.47 2.47 0 0 1 0 3.5l-3.88 3.88a1 1 0 1 0 1.42 1.42l3.88-3.89a4.49 4.49 0 0 0 0-6.33ZM8.83 15.17a1 1 0 0 0 1.1.22 1 1 0 0 0 .32-.22l4.92-4.92a1 1 0 0 0-1.42-1.42l-4.92 4.92a1 1 0 0 0 0 1.42Z"></path></svg></span></a></div> <img src="https://developers.cloudflare.com/cdn-cgi/image/onerror=redirect,width=820,height=360,format=svg/_astro/outbound-connection-after.CxPT16q0.svg" alt="Timeline showing the same outbound stream completing because the active connection keeps the Durable Object alive, with the inactivity window starting only after the connection closes" loading="lazy" decoding="async" width="820" height="360"> <p>If you are <a href="https://developers.cloudflare.com/agents/">building agents on Cloudflare</a>, this is especially relevant. An agent that streams tokens from an LLM while <a href="https://developers.cloudflare.com/agents/concepts/calling-llms/">calling models</a>, or that performs <a href="https://developers.cloudflare.com/agents/concepts/agentic-patterns/long-running-agents/">long-running tasks</a> over an outbound connection, now stays alive for the duration of that connection instead of being evicted mid-stream.</p> <p><strong>Limits:</strong></p> <ul> <li>Each outbound connection keeps the Durable Object alive for a maximum of <strong>15 minutes</strong>. After 15 minutes, the connection stops preventing eviction (the connection itself continues operating), and the <a href="https://developers.cloudflare.com/durable-objects/concepts/durable-object-lifecycle/">standard eviction rules</a> resume.</li> <li>The Durable Object's existing <a href="https://developers.cloudflare.com/durable-objects/platform/limits/">per-account instance limits</a> still apply.</li> </ul> <p>For more information, refer to <a href="https://developers.cloudflare.com/durable-objects/concepts/durable-object-lifecycle/">Lifecycle of a Durable Object</a>.</p>