I am running ES 6 in production and was testing our application in development for use with the latest ES 7. Things break. The issue is related to the default value of indices.breaker.fielddata.limit. In 6, the default is 60% https://www.elastic.co/guide/en/elasticsearch/reference/6.6/circuit-breaker.html, in 7 it is 40% https://www.elastic.co/guide/en/elasticsearch/reference/7.2/circuit-breaker.html. What's the reason behind this significant change?
Also I noted that for our application, indices.breaker.fielddata.limit needs to be increased even further on ES 7, using the same jvm.options. So it seems that ES 7 is using more memory. What is the cause of this (new bundled JVM, Lucene 8, ...)?