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da74323141
This commit refactors the handling of thread pool settings so that the individual settings can be registered rather than registering the top level group. With this refactoring, individual plugins must now register their own settings for custom thread pools that they need, but a dedicated API is provided for this in the thread pool module. This commit also renames the prefix on the thread pool settings from "threadpool" to "thread_pool". This enables a hard break on the settings so that: - some of the settings can be given more sensible names (e.g., the max number of threads in a scaling thread pool is now named "max" instead of "size") - change the soft limit on the number of threads in the bulk and indexing thread pools to a hard limit - the settings names for custom plugins for thread pools can be prefixed (e.g., "xpack.watcher.thread_pool.size") - remove dynamic thread pool settings Relates #18674
129 lines
4.1 KiB
Plaintext
129 lines
4.1 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`. The maximum size for this pool
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is `1 + # of available processors`.
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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`. The maximum size for this pool
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is `1 + # of available processors`.
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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 max 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 max 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 max 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 max 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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thread_pool:
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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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thread_pool:
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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 `core` and `max` 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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thread_pool:
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warmer:
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core: 1
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max: 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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