import NIO

func eventLoopGroupLifecycle(maxChannels: Int) throws {
    let group = MultiThreadedEventLoopGroup(numThreads: System.coreCount)
    defer {
        _ = try? group.syncShutdownGracefully()
    }
    let serverBoot = ServerBootstrap(group: group)
    let listeningChannel = try serverBoot.bind(host: "127.0.0.1", port: 0).wait()
    let port = Int(listeningChannel.localAddress!.port!)
    let clientBoot = ClientBootstrap(group: group)

    var clients: [EventLoopFuture<Channel>] = []

    for _ in 0..<maxChannels {
        let client = clientBoot.connect(host: "127.0.0.1", port: port)
        clients.append(client)
    }

    print("Waiting on connect")
    for n in 0..<maxChannels {
        _ = try clients[n].wait()
    }

    print("Waiting on close")
    for n in 0..<maxChannels {
        _ = try clients[n].wait().close().wait()
    }

    try listeningChannel.close().wait() // Triggers assertion right here!
    print("End of eventLoopGroupLifecycle()")
}

do {
    try eventLoopGroupLifecycle(maxChannels: 5000)
    print("Succeeded during test (re-run with greater concurrency!)")
} catch {
    print("Gently failed during test")
}