127 lines
3.9 KiB
Plaintext
127 lines
3.9 KiB
Plaintext
[[modules-threadpool]]
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== Thread Pool
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A node holds several thread pools in order to improve how threads memory consumption
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are managed within a node. Many of these pools also have queues associated with them,
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which allow pending requests to be held instead
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of discarded.
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There are several thread pools, but the important ones include:
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`generic`::
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For generic operations (e.g., background node discovery).
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Thread pool type is `scaling`.
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`index`::
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For index/delete operations. Thread pool type is `fixed`
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with a size of `# of available processors`,
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queue_size of `200`.
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`search`::
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For count/search/suggest operations. Thread pool type is `fixed`
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with a size of `int((# of available_processors * 3) / 2) + 1`,
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queue_size of `1000`.
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`get`::
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For get operations. Thread pool type is `fixed`
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with a size of `# of available processors`,
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queue_size of `1000`.
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`bulk`::
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For bulk operations. Thread pool type is `fixed`
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with a size of `# of available processors`,
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queue_size of `50`.
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`percolate`::
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For percolate operations. Thread pool type is `fixed`
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with a size of `# of available processors`,
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queue_size of `1000`.
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`snapshot`::
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For snapshot/restore operations. Thread pool type is `scaling` with a
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keep-alive of `5m` and a size of `min(5, (# of available processors)/2)`.
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`warmer`::
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For segment warm-up operations. Thread pool type is `scaling` with a
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keep-alive of `5m` and a size of `min(5, (# of available processors)/2)`.
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`refresh`::
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For refresh operations. Thread pool type is `scaling` with a
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keep-alive of `5m` and a size of `min(10, (# of available processors)/2)`.
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`listener`::
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Mainly for java client executing of action when listener threaded is set to true.
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Thread pool type is `scaling` with a default size of `min(10, (# of available processors)/2)`.
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Changing a specific thread pool can be done by setting its type-specific parameters; for example, changing the `index`
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thread pool to have more threads:
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[source,js]
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--------------------------------------------------
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threadpool:
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index:
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size: 30
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--------------------------------------------------
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NOTE: you can update thread pool settings dynamically using <<cluster-update-settings>>.
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[float]
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[[types]]
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=== Thread pool types
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The following are the types of thread pools and their respective parameters:
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[float]
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==== `fixed`
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The `fixed` thread pool holds a fixed size of threads to handle the
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requests with a queue (optionally bounded) for pending requests that
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have no threads to service them.
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The `size` parameter controls the number of threads, and defaults to the
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number of cores times 5.
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The `queue_size` allows to control the size of the queue of pending
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requests that have no threads to execute them. By default, it is set to
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`-1` which means its unbounded. When a request comes in and the queue is
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full, it will abort the request.
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[source,js]
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--------------------------------------------------
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threadpool:
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index:
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size: 30
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queue_size: 1000
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--------------------------------------------------
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[float]
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==== `scaling`
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The `scaling` thread pool holds a dynamic number of threads. This
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number is proportional to the workload and varies between the value of
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the `min` and `size` parameters.
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The `keep_alive` parameter determines how long a thread should be kept
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around in the thread pool without it doing any work.
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[source,js]
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--------------------------------------------------
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threadpool:
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warmer:
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min: 1
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size: 8
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keep_alive: 2m
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--------------------------------------------------
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[float]
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[[processors]]
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=== Processors setting
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The number of processors is automatically detected, and the thread pool
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settings are automatically set based on it. Sometimes, the number of processors
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are wrongly detected, in such cases, the number of processors can be
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explicitly set using the `processors` setting.
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In order to check the number of processors detected, use the nodes info
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API with the `os` flag.
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