Forking Workers

Explanation

Golem workers are single threaded. To achieve parallel execution, it is possible to spawn child workers and communicate with them using RPC, as described on the Worker to Worker communication page.

A simpler way is to use the fork API. The fork API consists of a single host function, defined as the following:

/// Indicates which worker the code is running on after `fork`
enum fork-result {
    /// The original worker that called `fork`
    original,
    /// The new worker
    forked
}
 
/// Forks the current worker at the current execution point. The new worker gets the `new-name` worker name,
/// and this worker continues running as well. The return value is going to be different in this worker and
/// the forked worker.
fork: func(new-name: string) -> fork-result;

When called, a new worker is created using the given name, with exactly the same state as the one that called the fork function. The execution continues in both the original and the new workers, with a different fork-result result value in each.

Usage

Using this fork function from a component that was created from Golem's built-in templates is straightforward because access to the Golem specific host functions is already set up.

The following code snippet demonstrates calling fork and continuing on two different parallel branches based on its result value:

use golem_rust::{fork, ForkResult};
 
match fork("new-worker") {
    ForkResult::Original => {
        // ...
    }
    ForkResult::Forked => {
        // ...
    }
}