74 lines
3.1 KiB
Plaintext
74 lines
3.1 KiB
Plaintext
[[index-modules-indexing-pressure]]
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== Indexing pressure
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Indexing documents into {es} introduces system load in the form of memory and
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CPU load. Each indexing operation includes coordinating, primary, and replica
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stages. These stages can be performed across multiple nodes in a cluster.
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Indexing pressure can build up through external operations, such as indexing
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requests, or internal mechanisms, such as recoveries and {ccr}. If too much
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indexing work is introduced into the system, the cluster can become saturated.
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This can adversely impact other operations, such as search, cluster
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coordination, and background processing.
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To prevent these issues, {es} internally monitors indexing load. When the load
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exceeds certain limits, new indexing work is rejected
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[discrete]
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[[indexing-stages]]
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=== Indexing stages
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External indexing operations go through three stages: coordinating, primary, and
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replica. See <<basic-write-model>>.
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[discrete]
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[[memory-limits]]
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=== Memory limits
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The `indexing_pressure.memory.limit` node setting restricts the number of bytes
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available for outstanding indexing requests. This setting defaults to 10% of
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the heap.
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At the beginning of each indexing stage, {es} accounts for the
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bytes consumed by an indexing request. This accounting is only released at the
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end of the indexing stage. This means that upstream stages will account for the
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request overheard until all downstream stages are complete. For example, the
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coordinating request will remain accounted for until primary and replica
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stages are complete. The primary request will remain accounted for until each
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in-sync replica has responded to enable replica retries if necessary.
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A node will start rejecting new indexing work at the coordinating or primary
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stage when the number of outstanding coordinating, primary, and replica indexing
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bytes exceeds the configured limit.
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A node will start rejecting new indexing work at the replica stage when the
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number of outstanding replica indexing bytes exceeds 1.5x the configured limit.
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This design means that as indexing pressure builds on nodes, they will naturally
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stop accepting coordinating and primary work in favor of outstanding replica
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work.
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The `indexing_pressure.memory.limit` setting's 10% default limit is generously
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sized. You should only change it after careful consideration. Only indexing
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requests contribute to this limit. This means there is additional indexing
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overhead (buffers, listeners, etc) which also require heap space. Other
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components of {es} also require memory. Setting this limit too high can deny
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operating memory to other operations and components.
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[discrete]
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[[indexing-pressure-monitoring]]
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=== Monitoring
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You can use the
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<<cluster-nodes-stats-api-response-body-indexing-pressure,node stats API>> to
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retrieve indexing pressure metrics.
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[discrete]
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[[indexing-pressure-settings]]
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=== Indexing pressure settings
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`indexing_pressure.memory.limit`::
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Number of outstanding bytes that may be consumed by indexing requests. When
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this limit is reached or exceeded, the node will reject new coordinating and
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primary operations. When replica operations consume 1.5x this limit, the node
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will reject new replica operations. Defaults to 10% of the heap.
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