Durable Objects Dynamic Workers Limit Jumps from 4 to 10!

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Cloudflare Changelog developers.cloudflare.com

Today I found a small but genuinely useful update around Cloudflare Durable Objects, so let's take a look together. It's a story about a limit getting relaxed.

What was announced?

According to the Cloudflare Changelog, the number of distinct Dynamic Workers a Durable Object can have with in-flight requests at the same time has been increased from 4 to 10.

Dynamic Workers is a mechanism that lets you spin up a Worker on demand by handing it code to run at execution time. It's used for things like AI agent "code mode," where an LLM generates code and runs it right on the spot. It's a primitive designed to safely execute untrusted code in a sandbox.

For regular Workers other than Durable Objects, the limit stays the same: up to 4 distinct Dynamic Workers per request.

The story so far

Until now, a Durable Object could only have up to 4 distinct Dynamic Workers with in-flight requests at once.

This limit applies across all concurrent requests to the same Durable Object, because a Durable Object shares a single input/output (I/O) context. So even when multiple requests arrived at the same time, they all shared one limit for that entire Durable Object. That meant if a single Durable Object was handling multiple sessions or users, each trying to run a different Dynamic Worker, it could hit the ceiling pretty quickly.

What changes

With the limit now raised to 10, a single Durable Object can run more distinct Dynamic Workers concurrently.

For example, if you're using a Durable Object to manage sessions or agent state for multiple users while running separate pieces of dynamic code for each of them, you should now run into the limit less often. If you're building an AI agent code-execution backend on top of Durable Objects, this is a quiet but welcome bit of breathing room.

Dive Deep

The source also spelled out exactly how the limit is counted, so here's a recap.

• The limit counts "distinct Dynamic Workers with in-flight requests"
• Multiple in-flight requests to the same Dynamic Worker count as just one toward the limit
• The Durable Objects limit (10) applies across all concurrent requests to the same Durable Object, since they share an I/O context
• The regular Workers limit (4) applies per request

For more detail, Cloudflare points to its "Dynamic Workers limits" documentation.

Wrap-up

• Durable Objects can now run up to 10 distinct Dynamic Workers concurrently, up from 4
• This limit is shared across the whole Durable Object, and multiple requests to the same Dynamic Worker count as one
• The regular Workers limit (4 per request) is unchanged
• This update matters if you're using Durable Objects for AI agent dynamic code execution or multi-session management