Cache size and Heap size

[Evgeniy Strokin]

Hello,.. 
I have relatively large RAM (10Gb) on my server which is running Solr. I 
increased Cache settings and start to see OutOfMemory exceptions, specially on 
facet search.
Is anybody has some suggestions how Cache settings related to Memory 
consumptions? What are optimal settings? How they could be calculated?
 
Thank you for any advise,
Gene