Circuit Breaker

Elasticsearch contains multiple circuit breakers used to prevent operations from causing an OutOfMemoryError. Each breaker specifies a limit for how much memory it can use. Additionally, there is a parent-level breaker that specifies the total amount of memory that can be used across all breakers.

These settings can be dynamically updated on a live cluster with the cluster-update-settings API.

Parent circuit breaker

The parent-level breaker can be configured with the following setting:

indices.breaker.total.limit
Starting limit for overall parent breaker, defaults to 70% of JVM heap.

Field data circuit breaker

The field data circuit breaker allows Elasticsearch to estimate the amount of memory a field will require to be loaded into memory. It can then prevent the field data loading by raising an exception. By default the limit is configured to 60% of the maximum JVM heap. It can be configured with the following parameters:

indices.breaker.fielddata.limit
Limit for fielddata breaker, defaults to 60% of JVM heap
indices.breaker.fielddata.overhead
A constant that all field data estimations are multiplied with to determine a final estimation. Defaults to 1.03

Request circuit breaker

The request circuit breaker allows Elasticsearch to prevent per-request data structures (for example, memory used for calculating aggregations during a request) from exceeding a certain amount of memory.

indices.breaker.request.limit
Limit for request breaker, defaults to 40% of JVM heap
indices.breaker.request.overhead
A constant that all request estimations are multiplied with to determine a final estimation. Defaults to 1