And from the RCA [1]:
> The immediate cause of the failure was network saturation on load balancers in Central US due to a new peak in traffic.
It is unbelivable that aload of 2.8b commits was totally fine, and a load of 2.9b was a sitewide outage, unless they have no reporting or their tooling is completely incompetent. If things can fall apart so easily, throwing more capacity at the problem won't fix it.
These backlogs can cause clients to make more retries, exacerbating the problem. Potentially further cascading through the system.
The art of large system design is to identify and avoid these kinds of chokepoints. And when something happens, propagate the "backpressure" up the stack to avoid queuing.
AWS got a fair share of similar outages, so the newer SDKs now try to not exacerbate these kinds of issues: https://docs.aws.amazon.com/sdkref/latest/guide/feature-retr...
The original AWS EBS outage is probably the canonical example: https://aws.amazon.com/message/65648/
Look, I hate Microslop as much as anyone but you'd have to purposely misinterpret TFA in order to arrive at this interpretation. C'mon.
> It is unbelivable that aload of 2.8b commits was totally fine, and a load of 2.9b was a sitewide outage
In my experience, there are hard thresholds that get passed that expose hidden bottlenecks like this. A previous system I worked on we had absolutely loads of headroom by all of our measured metrics, but one day we filled a cache because the value hadn’t been tweaked in recent memory. Plenty of space on disk and in memory, but all of a sudden we went from a very high cache hit rate to a very low cache hit rate, and everything ground to a halt.