It was a Googler misconfiguring a sync server that took out Chrome and Gmail on Monday, an engineer has stated on dev forums.
The reason for Gmail's brief burnout on Monday has been winkled out, and it was connected to the rolling crashes suffered on the Chrome browser on the same day.
It was a human error in configuring a Chrome component that throttled traffic in Chrome and then on several other Google services, explained Chrome engineer Tim Steele in a post on the Google code forum.
The component controlled traffic for Chrome Sync - a service that allows users to synchronise their customised Chrome browser across all of their devices, giving them the same bookmarks, widgets, settings and browsing history.
A small change to its configuration settings meant the load-balancing component started to throttle traffic when it wasn't supposed to. And because the component is core to the infrastructure that many Google services depend on, it affected them too.
It was Chrome Sync users who were hit by the outage first.
- Chrome Sync Server relies on a backend infrastructure component to enforce quotas on per-datatype sync traffic.
- That quota service experienced traffic problems today due to a faulty load balancing configuration change.
- That change was to a core piece of infrastructure that many services at Google depend on. This means other services may have been affected at the same time, leading to the confounding original title [the Gmail bug] of this bug.
- Because of the quota service failure, Chrome Sync servers reacted too conservatively by telling clients to throttle "all" data types, without accounting for the fact that not all client versions support all data types.
The crash is due to faulty logic responsible for handling "throttled" data types on the client when the data types are unrecognized.
There is WRONG in the cloud. ®