CloseKernels

✖
`CloseKernels`

Unsupported in Public Cloud

✖

terminates all parallel kernels from the list ParallelKernels[].

✖

CloseKernels[k]

terminates the kernel k.

✖

CloseKernels[{k₁,k₂,…}]

terminates the kernels k₁, k₂, ….

✖

CloseKernels["prop"]

terminates kernels that satisfy the given property.

Details

Kernels can be specified either using KernelObject, as returned by Kernels[], or using their integer IDs, as returned by $KernelID.
The following properties can be used to select a subset of all running kernels:

	All	all kernels
	"CloudKernels"	all cloud kernels
	"LinkKernels"	all link kernels
	"LocalKernels"	all kernels running locally
	"LWGKernels"	all LightweightGrid kernels
	"OneKernelPerMachine"	one kernel for each different machine
	"RemoteKernels"	all kernels on remote machines
	"SshKernels"	all SSH kernels
	"WSTPServerKernels"	all WSTPServer kernels

Closed kernels are removed from the list of kernels available for parallel computing, as given by ParallelKernels[].

Examples

open allclose all

Basic Examples (1)Summary of the most common use cases

Close all running parallel kernels:

In[1]:=1

✖

https://wolfram.com/xid/0b8cry1iuc-c44bcu

Out[1]=1

Scope (3)Survey of the scope of standard use cases

Close any parallel kernels that may be running and launch the default kernels:

In[1]:=1

✖

https://wolfram.com/xid/0b8cry1iuc-dkog2e

Out[1]=1

Close all kernels:

In[1]:=1

✖

https://wolfram.com/xid/0b8cry1iuc-bpsymj

Out[1]=1

Launch copies of the previously running kernels:

In[2]:=2

✖

https://wolfram.com/xid/0b8cry1iuc-niwbss

Out[2]=2

Launch kernels of various types:

In[1]:=1

✖

https://wolfram.com/xid/0b8cry1iuc-35v13h

Out[1]=1

Close all LWG kernels:

In[2]:=2

✖

https://wolfram.com/xid/0b8cry1iuc-f7hamd

Out[2]=2

Close all remote kernels:

In[3]:=3

✖

https://wolfram.com/xid/0b8cry1iuc-tgmqqw

Out[3]=3

Close all local kernels:

In[4]:=4

✖

https://wolfram.com/xid/0b8cry1iuc-v5oslg

Out[4]=4

Applications (1)Sample problems that can be solved with this function

Measure the speedup of the same calculation with different numbers of kernels used:

In[1]:=1

✖

https://wolfram.com/xid/0b8cry1iuc-e4oltv

Out[1]=1

Properties & Relations (1)Properties of the function, and connections to other functions

Distributed definitions and shared variables apply to running kernels and new ones:

In[1]:=1

✖

https://wolfram.com/xid/0b8cry1iuc-7g8x1

In[2]:=2

✖

https://wolfram.com/xid/0b8cry1iuc-naqc23

Out[2]=2

Packages read with ParallelNeeds also apply to running and new kernels:

In[3]:=3

✖

https://wolfram.com/xid/0b8cry1iuc-ef9rv

Close all running kernels and launch new ones:

In[4]:=4

✖

https://wolfram.com/xid/0b8cry1iuc-f1oma

Out[4]=4

The new kernels inherit previously distributed definitions and shared variables:

In[5]:=5

✖

https://wolfram.com/xid/0b8cry1iuc-bc5k33

Out[5]=5

The new kernels also inherit packages read previously:

In[6]:=6

✖

https://wolfram.com/xid/0b8cry1iuc-kzrk77

Out[6]=6

Possible Issues (1)Common pitfalls and unexpected behavior

If no kernels are available, most parallel calculations are done sequentially:

In[1]:=1

✖

https://wolfram.com/xid/0b8cry1iuc-7b004

In[2]:=2

✖

https://wolfram.com/xid/0b8cry1iuc-f9yca5

Out[2]=2

Top