Check getAlarm() first and keep preview off real Durable Objects
@graycoin retells the Durable Object alarm loop shared by @shmily7 and draws three habits: check getAlarm() before setAlarm(), do not bind preview environments to real Durable Objects, and reread AI-generated storage and scheduling code.
- Products
- Durable Objects
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- Author experience𝕏
- Author
- @graycoin
Key points
- The author retells that an unused test project’s Durable Object alarm, written by AI, looped and made about six trillion reads and writes.
- In his account, the model scheduled another alarm inside runAlarm and reused a checkpoint close to expiry; with a 30-day TTL and a 7-day refresh window, the problem stayed hidden for about three weeks.
- He frames it as per-use serverless billing meeting self-scheduling code without a circuit breaker, and advises calling getAlarm() before setAlarm(), not binding preview environments to real Durable Objects, and rereading AI-generated storage and scheduling code.
- Cloudflare’s Alarms API documentation says each Durable Object has one alarm at a time and calling setAlarm() overwrites an existing one; it recommends checking for an existing alarm when setting one in the constructor.
Original sources
Original source · Published
Read on 𝕏🔆
@graycoin · Original 𝕏 post
Codex，以后我们小心点吧。 一位老哥 1 万刀的 Cloudflare 账单。不是被攻击，不是跑了大流量，是一个没人用的测试项目，Durable Object 的 alarm 被 AI 写成了死循环，读写了 6 万亿次。 Vibe coding 写到一半，模型顺手在 runAlarm 里又排了一次闹钟，还复用了快过期的 checkpoint。TTL 30… https://t.co/JlKn7Pytvj
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