Kafka消费者丢失消息

There is Kafka Topic called "WebMessages" on 2 partions.

We have two consumer group in same server but in different site on IIS.

One of the consumer cannot receive messages. The other one missed most of the messages.

When I write simple consumer on my local computer, I also missed some messages. Any idea what's going wrong ?

Here is the producer code :

_producerConfig = new ProducerConfig {
                    BootstrapServers = _addressWithPort,
                    Acks = Acks.All
                };

using (var p = new ProducerBuilder<string, string>(_producerConfig).Build())
                {
                    p.ProduceAsync(_topicName, new Message<string, string>
                    {
                        Key = ldtoKafkaMessage.Key,
                        Value = ldtoKafkaMessage.Message
                    }).ContinueWith(task =>
                    {
                        if (task.IsFaulted)
                        {
                            TraceController.TraceError(Common.Enums.TraceEventCategories.X, "Key|Message", ldtoKafkaMessage.Key + " " + ldtoKafkaMessage.Message + " " + task.Exception.Message + " " + task.Exception.InnerException+ " " + task.Exception.StackTrace);
                        }
                        else
                        {
                            TraceController.TraceInformation(Common.Enums.TraceEventCategories.X, "Key|Message|Result", ldtoKafkaMessage.Key + " " + ldtoKafkaMessage.Message + " " + "Success");
                        }
                    });
                }

So I make sure that I sent messages to producer.

Here is the consumer code.

     _consumerConfig = new ConsumerConfig
        {
            BootstrapServers = _addressWithPort,
            AutoOffsetReset = AutoOffsetReset.Earliest,
            GroupId = consumerGroupId
        };

  using (var c = new ConsumerBuilder<string, string>(_consumerConfig).Build())
            {
                c.Subscribe(_topicName);

                CancellationTokenSource cts = new CancellationTokenSource();
                try
                {
                    while (!cts.IsCancellationRequested)
                    {
                        try
                        {
                            var cr = c.Consume(cts.Token);
                            LdtoKafkaMessage.Key = cr.Key;
                            LdtoKafkaMessage.Message = cr.Value;
                            this.OnMessageChanged();
                        }
                        catch (ConsumeException e)
                        {

                            Console.WriteLine($"Error occured: {e.Error.Reason}");
                        }
                    }
                }
                catch (OperationCanceledException)
                {
                    // Ensure the consumer leaves the group cleanly and final offsets are committed.
                    c.Close();
                }
            }