:@everywhere

@everywhere

Execute an expression on all processes. Errors on any of the processes are collected into a CompositeException and thrown.

Examples

Execute an expression on all processes:
```
julia> @everywhere begin
         x = 2
         println(x * myid())
       end
2
4
6
8
```
This example executes the given expression on all processes. In this case, it multiplies the value of x with the process ID (myid()) on each process and prints the result.

Use @everywhere with a function:

julia> @everywhere function greet(name)
         println("Hello, $name! I am process $myid().")
       end

julia> @everywhere greet("Julia")
Hello, Julia! I am process 2.
Hello, Julia! I am process 3.
Hello, Julia! I am process 4.
Hello, Julia! I am process 5.

This example defines a greet function and uses @everywhere to make it available on all processes. It then invokes the greet function with the argument "Julia" on each process.

Handling errors with @everywhere:

julia> @everywhere begin
         error("Oops, an error occurred on process $myid().")
       end
ERROR: On worker 2:
UndefVarError: error not defined
...
CompositeException:
4 exceptions occurred while handling task Task (worker=2):
...

In this example, an error is intentionally raised on each process using error. The errors are collected into a CompositeException and thrown. Each process will display its respective error message.

Common mistake example:

julia> @everywhere x = 10
ERROR: UndefVarError: x not defined
...

In this example, the variable x is not defined before using it with @everywhere. To avoid this error, ensure that all variables used in the expression are defined before executing it with @everywhere.

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:@everywhere

Examples

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