Increased heap usage after updating from 7.2.0 => 7.8.0

[7ca884569f2642e2c488 (Иван Сорокин)]

We updated our elastic (5 servers, two nodes each) from 7.2.0 to 7.8.0 and noticed that from this moment some new errors of type CircuitBreakingException started to occure and heap size can touch now 90-100% of available memory which was not the case on 7.2.0. Our routine didn't change.

Additional deatails and observations

1. Update was made without reindexing documents and just uses 7.2.0 data (can it affect something?)
2. We use default config for es in both cases
3. Docker container in both cases
4. Heap size is near 32Gb in both cases
5. After update we have permanent zero gc stat

"old": {
* "collection_count": 0,
* "collection_time_in_millis": 0
} 

which I think is strange
6) We use bundled java in both cases
7) I noticed that jdk changed from Oracle to AdoptOpenJdk, can it be connected with my problem?

[warkolm (Mark Walkom)]

Can you post the exception you are seeing, and ideally some of the Elasticsearch logs?

[7ca884569f2642e2c488 (Иван Сорокин)]

The remote server returned an error: (429) Too Many Requests.. Call: Status code 429 from: POST /regions/_search?typed_keys=true. ServerError: Type: circuit_breaking_exception Reason: "[parent] Data too large, data for [<http_request>] would be [32723739866/30.4gb], which is larger than the limit of [31621696716/29.4gb], real usage: [32723739456/30.4gb], new bytes reserved: [410/410b], usages [request=0/0b, fielddata=359734446/343mb, in_flight_requests=3008/2.9kb, accounting=4402798/4.1mb]"