c# - 如何确定 Azure ServiceBus PrefetchCount 和 ReceiveBatch 大小

Question

我有一个队列处理器，它从 ServiceBus 队列中检索所有消息。我想知道如何确定 MessageReceiver PrefetchCount和 ReceiveBatch messageCount以优化性能。我目前将它们设置为任意数字 500，如下所示:

var receiverFactory = MessagingFactory.CreateFromConnectionString("ConnectionString");
var receiver = await receiverFactory.CreateMessageReceiverAsync("QueueName", ReceiveMode.PeekLock);
receiver.PrefetchCount = 500;

bool loopBatch = true;
while (loopBatch) 
{
    var tempMessages = await receiver.ReceiveBatchAsync(500, TimeSpan.FromSeconds(1));
    // Do some message processing...
    loopBatch = tempMessages.Any();
}

运行时，我发现我的批处理通常需要时间“预热”，检索诸如“1, 1, 1, 1, 1, 1, 1, 1, 125, 125, 125, 125.. .”，批量检索数突然跳得更高。

来自Prefetching optimization文档:

When using the default lock expiration of 60 seconds, a good value for SubscriptionClient.PrefetchCount is 20 times the maximum processing rates of all receivers of the factory. For example, a factory creates 3 receivers, and each receiver can process up to 10 messages per second. The prefetch count should not exceed 20 X 3 X 10 = 600. By default, QueueClient.PrefetchCount is set to 0, which means that no additional messages are fetched from the service.

当批量检索似乎一次检索的消息数量差异很大时，我真的不明白如何确定接收者的“每秒消息数”。任何帮助将不胜感激。

Answer 1

I don't really understand how to determine the receiver's "messages per second" when the batch retrieval seems to retrieve widely-varying numbers of messages at a time.

预取在使用 OnMessage API 的场景中更有意义。在这种情况下，会注册一个回调，该回调接受一条消息进行处理，您可以估计该消息的平均处理时间。 OnMessage API 允许定义将运行多少并发回调。如果知道有源源不断的传入消息流，那么逐一检索消息的效率将极其低下。因此，PrefetchCount 用于指定客户端应在后台“批量”检索多少条消息，以将往返保存回服务器。