Rename existing circuit breakers for clarity

[lanerjo]

Existing circuit breakers should be more appropriately named. eg.

• indices.breaker.total.use_real_memory -> breaker.parent.total.use_real_memory
• indices.breaker.total.limit -> breaker.parent.total.limit
• indices.breaker.request.limit -> breaker.request.limit (unless this is truly a per index breaker)
• indices.breaker.request.overhead -> breaker.request.overhead
• indices.breaker.accounting.limit -> breaker.memory.accounting.limit (unless this is per index)
• indices.breaker.accounting.overhead -> breaker.memory.accounting.overhead

[elasticmachine]

Pinging @elastic/es-core-infra (:Core/Infra/Circuit Breakers)

[soarescaique]

Hey guys, Can I get this issue resolved?

[rjernst]

@lanerjo We appreciate your desire to improve the naming of circuit breaker settings. Naming is important; good names can ease configuration, and bad names can confuse. With that said, changing existing configuration names in Elasticsearch is not a trivial matter, it must be done with care, and we choose carefully when to undertake such changes due to the massive impact they can have. For these settings, the indices prefix is standard practice, so the prefix actually helps, rather than hurts, users to find the settings. It is possible there is still reason to make this change, but I don't see any justification in the description here, just a suggestion to remove the prefix. Could you please provide some reasoning why you think this change should be made?

[lanerjo]

The existing naming convention implies that the circuit breakers apply to indices, when that is not the case.
This is misleading and inaccurate.

I do understand that this is not a trivial matter, you need to keep backwards compatibility for a period of time, to ensure that users have a chance to migrate to the new settings, and that a decision such as this should not be taken lightly.

The circuit breakers can be tripped on requests that do not include indices, such as cluster state, and inter cluster communication. Thus this naming convention can be very misleading and compounding to an already difficult to diagnose scenario.