Concurrent queue issue

gistfile1.txt

let queue = DispatchQueue(label: "Queue", qos: .default, attributes: [.concurrent], autoreleaseFrequency: .workItem, target: .global(qos: .default))

let cancellable = [1, 2, 3, 4, 5].publisher
    .receive(on: queue)
    .map { longRunningFunc(value: $0) }
    .receive(on: DispatchQueue.main)
    .sink (receiveCompletion: { completion in
        Swift.print(completion)
    }, receiveValue: { value in
        Swift.print(value)
    })

func longRunningFunc(value: Int) -> Int {
    
    let total = Int.random(in: 0..<100000)
    
    // This is slow enough in a Playground
    for i in 1..<total {
        i + 1
    }
    
    return value
}