Thread Pooledit

A node holds several thread pools in order to improve how threads are managed and memory consumption within a node. There are several thread pools, but the important ones include:

index

For index/delete operations, defaults to fixed, size # of available processors. queue_size 200.

search

For count/search operations, defaults to fixed, size 3x # of available processors. queue_size 1000.

suggest

For suggest operations, defaults to fixed, size # of available processors. queue_size 1000.

get

For get operations, defaults to fixed size # of available processors. queue_size 1000.

bulk

For bulk operations, defaults to fixed size # of available processors. queue_size 50.

percolate

For percolate operations, defaults to fixed size # of available processors. queue_size 1000.

snapshot

For snapshot/restore operations, defaults to scaling keep-alive 5m, size (# of available processors)/2.

warmer

For segment warm-up operations, defaults to scaling with a 5m keep-alive.

refresh

For refresh operations, defaults to scaling with a 5m keep-alive.

Changing a specific thread pool can be done by setting its type and specific type parameters, for example, changing the index thread pool to have more threads:

threadpool:
    index:
        type: fixed
        size: 30
Note

you can update threadpool settings live using Cluster Update Settings.

Thread pool typesedit

The following are the types of thread pools that can be used and their respective parameters:

cacheedit

The cache thread pool is an unbounded thread pool that will spawn a thread if there are pending requests. Here is an example of how to set it:

threadpool:
    index:
        type: cached

fixededit

The fixed thread pool holds a fixed size of threads to handle the requests with a queue (optionally bounded) for pending requests that have no threads to service them.

The size parameter controls the number of threads, and defaults to the number of cores times 5.

The queue_size allows to control the size of the queue of pending requests that have no threads to execute them. By default, it is set to -1 which means its unbounded. When a request comes in and the queue is full, it will abort the request.

threadpool:
    index:
        type: fixed
        size: 30
        queue_size: 1000

Processors settingedit

The number of processors is automatically detected, and the thread pool settings are automatically set based on it. Sometimes, the number of processors are wrongly detected, in such cases, the number of processors can be explicitly set using the processors setting.

In order to check the number of processors detected, use the nodes info API with the os flag.