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$DefaultKernels

is the list of kernels that are configured for parallel computing.

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$DefaultKernels

As of Version 13.3, $DefaultKernels has been superseded by $DefaultParallelKernels.

$DefaultKernels

is the list of kernels that are configured for parallel computing.

Details

  • On a multicore computer, the list typically includes as many local kernels as there are cores, up to a limit defined by license availability.
  • Additional configurations for kernels on remote machines can be made available with the Wolfram Lightweight Grid and the Cluster Integration Package.

Examples

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Basic Examples  (3)

The default value of $DefaultKernels:

Wolfram Language code: $DefaultKernels

When no kernels are running, LaunchKernels uses this list as the default to launch kernels:

Wolfram Language code: CloseKernels[];LaunchKernels[]

Kernels can be specified using URL syntax:

Wolfram Language code: $DefaultKernels = { "file:///usr/local/bin/wolfram?4", "ssh://sirius//usr/local/bin/wolfram130?4", "wstp://raspi8?2", "lwg://gcov.wolfram.com?2" }
Wolfram Language code: LaunchKernels[]

Kernels can be specified using KernelConfiguration:

Wolfram Language code: $DefaultKernels = { KernelConfiguration["localhost", "KernelCount" -> 4], KernelConfiguration["sirius", "KernelCount" -> 4, "KernelCommand" -> "wolfram130"], KernelConfiguration["wstp://raspi8", "KernelCount" -> 2] }
Wolfram Language code: LaunchKernels[]

Applications  (2)

Remember the current value of $DefaultKernels persistently between sessions:

Wolfram Language code: InitializationValue[$DefaultKernels] = $DefaultKernels

In a new session, the value is restored:

Wolfram Language code: Quit[]
Wolfram Language code: $DefaultKernels

Remove any persistent value:

Wolfram Language code: Remove[InitializationValue[$DefaultKernels]]

In the next session, the value reverts to the default:

Wolfram Language code: Quit[]
Wolfram Language code: $DefaultKernels
Wolfram Research (2021), $DefaultKernels, Wolfram Language function, https://reference.wolfram.com/language/ref/$DefaultKernels.html.

Text

Wolfram Research (2021), $DefaultKernels, Wolfram Language function, https://reference.wolfram.com/language/ref/$DefaultKernels.html.

CMS

Wolfram Language. 2021. "$DefaultKernels." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/$DefaultKernels.html.

APA

Wolfram Language. (2021). $DefaultKernels. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/$DefaultKernels.html

BibTeX

@misc{reference.wolfram_2026_$defaultkernels, author="Wolfram Research", title="{$DefaultKernels}", year="2021", howpublished="\url{https://reference.wolfram.com/language/ref/$DefaultKernels.html}", note=[Accessed: 13-June-2026]}

BibLaTeX

@online{reference.wolfram_2026_$defaultkernels, organization={Wolfram Research}, title={$DefaultKernels}, year={2021}, url={https://reference.wolfram.com/language/ref/$DefaultKernels.html}, note=[Accessed: 13-June-2026]}