Julia bounded worker pool with error capture

function pool_map(f, inputs; workers=4)
    jobs = Channel{Tuple{Int,Any}}(length(inputs))
    foreach(x -> put!(jobs, x), collect(enumerate(inputs)))
    close(jobs)
    results, errors = Vector{Any}(fill(nothing, length(inputs))), Tuple{Int,Any}[]
    guard = ReentrantLock()
    Threads.@threads for _ in 1:workers  # workers drain the shared channel
        for (i, x) in jobs
            try
                results[i] = f(x)
            catch err
                lock(guard) do
                    push!(errors, (i, err))
                end
            end
        end
    end
    return results, errors
end

println(pool_map(x -> x^2, 1:5; workers=2))