• Home
• Julia

:@spawn

@spawn

Creates a closure around an expression and runs it on an automatically-chosen process, returning a RemoteRef to the result.

Examples

Examples:

1. Using @spawn to perform a simple computation:

   julia> res = @spawn 2 + 2
   RemoteRef{Channel{Any}}(1, 1, 2, Nullable{Any}())

   This example creates a closure around the expression 2 + 2 and runs it on a automatically-chosen process. It returns a RemoteRef which represents the result of the computation.

2. Spawning a more complex computation:

   julia> a = [1, 2, 3, 4, 5];
   julia> b = [6, 7, 8, 9, 10];
   julia> res = @spawn sum(a .* b)
   RemoteRef{Channel{Any}}(1, 1, 2, Nullable{Any}())

   In this example, @spawn is used to create a closure that calculates the dot product of arrays a and b. The result is stored in a RemoteRef object.

3. Using @spawn in a loop:

   julia> results = Vector{RemoteRef}()
   julia> for i in 1:10
             push!(results, @spawn i^2)
         end
   julia> fetch.(results)
   10-element Vector{Int64}:
   1
   4
   9
   16
   25
   36
   49
   64
   81
   100

   This example demonstrates how to use @spawn in a loop. It spawns the computation of i^2 for each value of i from 1 to 10. The fetch. function is then used to retrieve the results from the RemoteRef objects.

Common mistake example:

julia> res = @spawn println("Hello, World!")
ERROR: `@spawn` macro: expression to `@spawn` must return a value to be fetched

In this example, the expression passed to @spawn is a println statement, which doesn't return a value. The @spawn macro expects an expression that returns a value, as it creates a closure around that expression and runs it on a separate process. Make sure the expression passed to @spawn returns a value that can be fetched.

See Also

User Contributed Notes

Add a Note

The format of note supported is markdown, use triple backtick to start and end a code block.