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Circuit Breaker

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Circuit Breaker

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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.

Except where noted otherwise, these settings can be dynamically updated on a live cluster with the cluster-update-settings API.

Parent circuit breaker

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

indices.breaker.total.use_real_memory
Static setting determining whether the parent breaker should take real memory usage into account (true) or only consider the amount that is reserved by child circuit breakers (false). Defaults to true.
indices.breaker.total.limit
Starting limit for overall parent breaker, defaults to 70% of JVM heap if indices.breaker.total.use_real_memory is false. If indices.breaker.total.use_real_memory is true, defaults to 95% of the JVM heap.

Field data circuit breaker

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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 40% of the maximum JVM heap. It can be configured with the following parameters:

indices.breaker.fielddata.limit
Limit for fielddata breaker, defaults to 40% 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

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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 60% of JVM heap
indices.breaker.request.overhead
A constant that all request estimations are multiplied with to determine a final estimation. Defaults to 1

In flight requests circuit breaker

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The in flight requests circuit breaker allows Elasticsearch to limit the memory usage of all currently active incoming requests on transport or HTTP level from exceeding a certain amount of memory on a node. The memory usage is based on the content length of the request itself. This circuit breaker also considers that memory is not only needed for representing the raw request but also as a structured object which is reflected by default overhead.

network.breaker.inflight_requests.limit
Limit for in flight requests breaker, defaults to 100% of JVM heap. This means that it is bound by the limit configured for the parent circuit breaker.
network.breaker.inflight_requests.overhead
A constant that all in flight requests estimations are multiplied with to determine a final estimation. Defaults to 2.

Accounting requests circuit breaker

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The accounting circuit breaker allows Elasticsearch to limit the memory usage of things held in memory that are not released when a request is completed. This includes things like the Lucene segment memory.

indices.breaker.accounting.limit
Limit for accounting breaker, defaults to 100% of JVM heap. This means that it is bound by the limit configured for the parent circuit breaker.
indices.breaker.accounting.overhead
A constant that all accounting estimations are multiplied with to determine a final estimation. Defaults to 1

Script compilation circuit breaker

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Slightly different than the previous memory-based circuit breaker, the script compilation circuit breaker limits the number of inline script compilations within a period of time.

See the "prefer-parameters" section of the scripting documentation for more information.

script.max_compilations_rate
Limit for the number of unique dynamic scripts within a certain interval that are allowed to be compiled. Defaults to 75/5m, meaning 75 every 5 minutes.
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