fair

Added in version 23.04

The fair directive, when enabled, guarantees that process outputs will be emitted in the order in which they were received. For example:

process hello {
    fair true

    input:
    val x

    output:
    tuple val(task.index), val(x)

    script:
    """
    sleep \$((RANDOM % 3))
    """
}

workflow {
    channel.of('A','B','C','D') | hello | view
}

The above example produces:

[1, A]
[2, B]
[3, C]
[4, D]