CRITICAL : Continues GC on EXSI server

Hi All,
In one of our production environment, there are around 250 million records. I am running elastic 2.2 and it has 17GB of the heap, 32 CPU core on EXSI server. There is a background thread which summarises this 250 million records. I am seeing continuous GC and at some point Elastic become unresponsive. We have different unix machine which has 6.5 billion record and there are perfectly file with the same operation. Can someone help on this?