cf-worker-clocks

A test Cloudflare worker and durable object which demonstrates problems that can arise from Cloudflare's reuse of JavaScript execution context.

Demonstrating the issue

npm install

npx wrangler publish

Then in a browser open: https://<worker-domain>/sleepInLock?seconds=40000 or https://<worker-domain>/fetchInLock?seconds=40000

Then without modifying the code run

npx wrangler publish

or

npx wrangler tail

The publish/tail will cause the above sleepInLock/fetchInLock request to be cancelled, and the DO to throw an exception: Durable Object reset because its code was updated.

Then in a browser open: https://<worker-domain>/checkLock

Which will show that the lock is still held, because the timeout/fetch for the cancelled request did not resolve or reject, and so the lock was not released. The lock will now be stuck locked until the Durable Object is restarted in a different JavaScript Execution Context. This can be forced by slightly modifying the code and running wrangler publish.