I am trying to do some test with RocketMQ, and I use C# with Newlife.RocketMQ. I started RocketMQ on my pc and I see the command window open and printing messages -- so that is ok.

So I wrote a simple C# program to test this:

This is the WPF window:

<Window x:Class="WpfApp1.MainWindow"
 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
 xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
 xmlns:local="clr-namespace:WpfApp1"
 mc:Ignorable="d"
 Title="MainWindow" Height="450" Width="800" >
<DockPanel >
 <TextBox x:Name="txtProduce" Text="message 1" DockPanel.Dock="Top" Height="30" FontSize="16"/>
 <Button x:Name="btnProduce" Content="Produce" HorizontalAlignment="Left" VerticalAlignment="Top" Width="75" Click="BtnProduce_Click" DockPanel.Dock="Top"/>
 <DataGrid x:Name="dgProduce" Height="100" DockPanel.Dock="Top" IsReadOnly="True"/>
 <Label Content="Consumer" DockPanel.Dock="Top"/>
 <DataGrid x:Name="dgConsume" IsReadOnly="True"/>
</DockPanel>
</Window>

And now the C# code:

public partial class MainWindow : Window
{
 Producer _producer;
 Consumer _consumer;
 ObservableCollection<SendResult> _results = new ObservableCollection<SendResult>();
 object _resultsLock = new object();
 ObservableCollection<MessageExt> _messages = new ObservableCollection<MessageExt>();
 object _messagesLock = new object();
 public MainWindow()
 {
 InitializeComponent();
 dgProduce.ItemsSource = _results;
 BindingOperations.EnableCollectionSynchronization(_results, _resultsLock);
 dgConsume.ItemsSource = _messages;
 BindingOperations.EnableCollectionSynchronization(_messages, _messagesLock);
 _producer = new Producer
 {
 Topic = "TopicTest",
 NameServerAddress = "localhost:9876",
 RetryTimesWhenSendFailed = 10
 };
 _producer.Start();
 _consumer = new Consumer
 {
 Topic = "TopicTest",
 NameServerAddress = "localhost:9876"
 };
 _consumer.OnConsume = (q, ms) =>
 {
 foreach(var item in ms.ToList())
 _messages.Add(item);
 return true;
 };
 _consumer.Start();
 }
 private int _i = 1;
 private void BtnProduce_Click(object sender, RoutedEventArgs e)
 {
 try
 {
 var content = DateTime.Now.ToString("yyyy/MM/dd HH:mm:ss.fff") + ":" + txtProduce.Text;
 var message = new Message()
 {
 Body = System.Text.Encoding.Default.GetBytes(content),
 Keys = (_i++).ToString(),
 Tags = _i % 2 == 0 ? "even" : "odd",
 Flag = 0,
 WaitStoreMsgOK = true
 };
 var sr = _producer.Publish(message);
 _results.Add(sr);
 txtProduce.Text = "message " + _i;
 }
 catch (Exception ex)
 {
 MessageBox.Show(ex.Message);
 }
 }
}

And now I see problems:

1. "message 3" appear twice in the consumer message list.
2. when I start 2 instances of my application, when a message is sent, it is consumed by either application instance 1 or instance 2, and not both.

Why this happen?