garbage collector choice and tuning

[Guy Laden]

Hi, We are considering CMS vs G1 for ZooKeeper running under Oracle JDK8.
The expected heap size is 4-6GB.
How workload-specific is this choice in your opinion and it what ways? E.g.
if many short sessions prefer G1, etc...
Has anybody had experience they're willing to share regarding this?
We'd also be very interested to hear about any gc-tuning flags you've had
good experience with.
Thanks