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Re: [tlaplus] Will there be a lesson learned on AWS 2025 East-1 Outage due to DynamoDB with regards to TLA+?



"TLA+ is used in DynamoDB" doesn't mean everything is checked with TLA+. And the race condition was in the DNS service, so someone would have to think about the consequences of race conditions in a low-concurrency database of DNS records. You wouldn't even need TLA+ for that. For so long, checking and then updating DNS records non-atomically has been OK that no one thought it would be an issue.

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Felipe

On Wed, Oct 29, 2025 at 3:09 PM Andrew Helwer <andrew.helwer@xxxxxxxxx> wrote:
Depends on whether someone who works at Amazon decides to write a TLA+ spec reproducing the bug or not; I don't think anybody outside the company has enough detail to do it. Amazon seems to have largely shifted from TLA+ to P as championed by Ankush Desai, but Ankush recently left Amazon so who knows what the future of Amazon formal methods use looks like. The last TLA+ conference was associated with ETAPS, and one of the industry track ETAPS talks was from an AWS employee where they talked about using a new Rust-based model-checker called Kani.

Andrew

On Mon, Oct 27, 2025 at 8:50 AM Chris Ortiz <zitroomega@xxxxxxxxx> wrote:
Some people say it is a race condition, but as I understand TLA+ is used in DynamoDB and can catch behavior such as this thatcould have been prevented. 

Thanks,
Zitro

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