Consider replacing Rails counter_cache with counter_culture gem
counter_culture provides more powerful cached counters and better deadlock handling then Rails counter_cache.
We should consider migrating all our counters to use it.
I recommend this be considered if needed after changing to rails 4.x which does a slightly better job of handling counters.
The reason not to do so right away is that this introduces a fairly complex gem as dependency, which is not very actively developed, and might lead to other issues then the ones we are currently facing (deadlocks, creating complex counting logic for some counters)