[quatrefoil]

It's not even that: the quoted language doesn't even blame the library - it appears to blame increased load.

"As a result of increased demand, it mixed up device ID" - no, it mixed up IDs as a result of some sort of a concurrency bug. I don't understand the point of deflecting this far.

[matthewcford]

Likely to be a multi-threading issue; my bet is the cache client wasn't thread-safe. I've seen this in some apps before and the solution was to turn off multi-threading while we debug the library that was causing the issue.

[sabujp]

This is the answer!