Parallel AsyncSteps

Parallel worker pool is created as a special step through asi.parallel() call:

• Each worker creates a “sub-thread”.
• All workers share the same state.
• Not recovered error in any of the workers immediately cancels other workers. The error is used to unwind parent async stack.
• It’s allowed to create inner parallel steps inside any worker step.
• There is implicit synchronization barrier at the end.

asi.add( (asi) => {
    const p = asi.parallel();
    
    p.add( (as) => parallel_A() );
    p.add( (as) => parallel_B() );
    p.add( (as) => parallel_C() );
    
    as.add( (asi) => {
        // all parallel steps must be finished
    } );
} );

Note on parallelization

1. All parallel steps utilize the same CPU - there is no scaling.
2. Such parallelization is designed for external event waiting.