@Xon Not super familiar with Redis, but I'm getting a lot of issues with timeouts and what appears to be malformed data. Don't see anything in the Redis log, and the latency between the web and db server containing redis is below 1ms so I can't imagine that's triggering the timeout. Hopefully this is something you've run into and it's a simple fix, have switched back to memcache temporarily but would really like to get Redis working again as it caused a huge page generation improvement
Edit: Additional details, FWIW it worked flawlessly for days and then suddenly this started happening this morning
You normally see this when Redis is saving to disk and the fork latency blows out. Simple solution is to not use "save" statements in the redis config since this fork's the entire process to snapshot Redis's memory which can be expensive under a xen hypervisor.
Persistent connections make this worse as it causes a bad connection to be re-used. I thought the latest code would attempt to discard it but I guess it isn't.
Ended up having this issue pop back up, created local read only slaves and the issue is gone. I think there may have been some latency created by the large number of requests to that single instance. Has been error free for a few days now!