如果队列消息字节长度大于x-max长度字节，RabbitMQ如何处理?

I had declare a queue like below:

我已经声明了如下队列:

Map<String, Object> args = new HashMap<String, Object>();
args.put("x-max-length-bytes", 2 * 1024 * 1024);  // Max length is 2G
channel.queueDeclare("queueName", true, false, false, args);

When the queue messages count bytes is large than 2G, It will auto remove the message on the head of the queue.
But what I expected is That it reject produce the last message and return exception to the producer.
How can I get it?

当队列消息数字节数大于2G时，它将自动删除队列头部的消息。但我所期望的是，它拒绝生成最后一条消息，并将异常返回给生成器。我怎样才能得到它?

2 个解决方案

#1

A possible workaround is check the queue size before send your message using the HTTP API.

一个可能的解决方案是在使用HTTP API发送消息之前检查队列大小。

For example if you have a queue called: myqueuetest with max size = 20.

例如，如果您有一个队列:myqueuetest和max size = 20。

Before send the message you can call the HTTP API in this way: http://localhost:15672/api/queues/

在发送消息之前，您可以这样调用HTTP API: http://localhost:15672/ API /queues/。

the result is a JSON like this:

结果是这样的JSON:

  "message_bytes":10,
  "message_bytes_ready":10,
  "message_bytes_unacknowledged":0,
  "message_bytes_ram":10,
  "message_bytes_persistent":0,
..
  "name":"myqueuetest",
  "vhost":"test",
  "durable":true,
  "auto_delete":false,
  "arguments":{
     "x-max-length-bytes":20
  },

then you cloud read the message_bytes field before send your message and then decide if send or not.

然后，在发送消息之前，您将读取message_bytes字段，然后决定是否发送消息。

Hope it helps

希望它能帮助

EDIT

编辑

This workaround could kill your application performance
这种方法可能会破坏您的应用程序性能。
This workaround is not safe if you have multi-threading/more publisher
如果您有多线程/更多的发布者，这个解决方案是不安全的。
This workaround is not a very "best practise"
这种变通方法并不是一种“最佳实践”

Just try to see if it is ok for your application.

试着看看你的申请是否可以。

#2

As explained on the official docs:

正如官方文件所解释的那样:

Messages will be dropped or dead-lettered from the front of the queue to make room for new messages once the limit is reached.

当到达极限时，消息将从队列的前端删除或挂起，以便为新消息腾出空间。

https://www.rabbitmq.com/maxlength.html

If you think RabbitMQ should drop messages form the end of the queue, feel free to open an issue here so we can discuss about it https://github.com/rabbitmq/rabbitmq-server/issues

如果您认为RabbitMQ应该从队列的末尾删除消息，那么您可以在这里打开一个问题，以便我们可以讨论它的https://github.com/rabbitmq/rabbitmq-server/issues。

#1