New Redis LATENCY DOCTOR command example

gistfile1.txt

127.0.0.1:6379> config set latency-monitor-threshold 10
OK
127.0.0.1:6379> debug sleep .1
OK
127.0.0.1:6379> debug sleep .2
OK
127.0.0.1:6379> debug sleep .3
OK
127.0.0.1:6379> latency doctor
Dave, I have observed latency spikes in this Redis instance.
You don't mind talking about it, do you Dave?

1. command: 2 latency spikes (average 250ms, mean deviation 50ms, period 2.50 sec).
   Worst all time event 300ms.

I have a few advices for you:

- Check your Slow Log to understand what are the commads you are running
  which are too slow to execute. Please check http://redis.io/commands/slowlog
  for more information.
- Deleting, expiring or evicting (because of maxmemory policy) large objects is
  a blocking operation. If you have very large objects that are often deleted,
  expired, or evicted, try to fragment those objects into multiple smaller objects.
127.0.0.1:6379>

Note: it reports 2 latency spikes since latency spikes of the same class in the same second are merged. Our time series is limited in size to avoid enlarging the Redis server base memory footprint.