fetchOutputs - Retrieve results from function running in the background - MATLAB (original) (raw)

Retrieve results from function running in the background

Syntax

Description

[[Y1,...,Ym](#mw%5F5bb50736-f285-4816-af51-143ac5aef6be)] = fetchOutputs([F](#mw%5F99069dba-6f36-49cd-bc09-227b66bf3129)) retrieves m results from a Future arrayF.

Each element in F must return at least m output arguments. To check how many output arguments a Future object has, use theNumOutputArguments property.

MATLAB® waits for the function associated with each element in F to finish before retrieving results from that element. The State property of a Future object is 'finished' when the associated function is finished. When you use fetchOutputs, MATLAB sets the Read property of each element inF to true.

You create a Future object when you use parfeval,parfevalOnAll, afterEach, orafterAll to:

Run a function in the background using backgroundPool.
Run a function on a parallel pool worker when you use Parallel Computing Toolbox™.

If F is an array of Future objects, the jth output from each element in F is concatenated to form the output Yj. Use this syntax only if the jth output from each element can be concatenated along the first dimension.

example

[[Y1,...,Ym](#mw%5F5bb50736-f285-4816-af51-143ac5aef6be)] = fetchOutputs([F](#mw%5F99069dba-6f36-49cd-bc09-227b66bf3129),UniformOutput=false) retrieves m results as cell arrays from a Future arrayF.

If F is an array of Future objects, the jth output from each element in F is concatenated in a cell array to form the output Yj. Use this syntax if, for any output of Yj, you are unable to concatenate the output from each element along the first dimension.

Examples

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This example shows how to run a function in the background using parfeval and backgroundPool. When you run a function in the background, you can run other MATLAB® code at the same time.

Use parfeval to run the function magic(3) and retrieve one output. Specify backgroundPool as the first argument to run the function in the background. When you use parfeval, you create a Future object.

f = parfeval(backgroundPool,@magic,1,3);

To retrieve the output from the background, use fetchOutputs. MATLAB returns the output once the execution of magic is complete.

ans = 3×3

 8     1     6
 3     5     7
 4     9     2

Input Arguments

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Input Future, specified as a parallel.Future scalar or array.

Example: F = parfeval(backgroundPool,@magic,1,3);

Output Arguments

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Output arguments from futures. The type of the outputs depends on theFuture scalar or array f, and the functions eachFuture is associated with.

If UniformOutput is specified as false, the jth output argument is a cell array containingn elements, where n is the number of elements in F.
Otherwise, the jth output argument is an array of type returned by the jth output of each element inF.

Each element in F must return at least m output arguments. To check how many output arguments a Future has, use the NumOutputArguments property.

Version History

Introduced in R2013b