问题描述
使用 Azure Service Bus，提供应用程序之间松耦合的消息交换，但是有时候发送消息多次出现超时错误。
A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.
ErrorCode: TimedOut (ServiceCommunicationProblem)
为了预防这类偶发的Timedout异常对应用的影响，需要重新再次发送或接收消息，是否有内置的重试机制呢？
问题解答
有的，Service Bus的SDK有内置的重试机制，通过ServiceBusRetryOptions 配置。其中，默认的MaxRetries 次数为3次，每次重试的间隔时间默认为 60秒。
如在 .NET应用代码中使用示例：
using Azure.Messaging.ServiceBus;
string connectionString = "<connection_string>";
string queueName = "<queue_name>";
// Because ServiceBusClient implements IAsyncDisposable, we'll create it
// with "await using" so that it is automatically disposed for us.
var options = new ServiceBusClientOptions();
options.RetryOptions = new ServiceBusRetryOptions
{
Delay = TimeSpan.FromSeconds(10),
MaxDelay = TimeSpan.FromSeconds(30),
Mode = ServiceBusRetryMode.Exponential,
MaxRetries = 3,
};
await using var client = new ServiceBusClient(connectionString, options);
对于 Timeout 的异常，如果持续一小段（间断性）发送，可以通过 telnet 或 psping 来查看端口，网络稳定性。
# 测试端口，服务器是否能ping通
telnet <yournamespacename>.servicebus.chinacloudapi.cn 5671
#测试是否存在网络丢包问题
.\psping.exe -n 25 -i 1 -q <yournamespace>.servicebus.chinacloudapi.cn:5671 -nobanner
参考资料
Service Bus的重试策略：https://learn.microsoft.com/zh-cn/azure/architecture/best-practices/retry-service-specific#retry-mechanism-6
Service Bus Timeout 异常 ：https://docs.azure.cn/zh-cn/service-bus-messaging/service-bus-troubleshooting-guide#connectivity-certificate-or-timeout-issues
Service Bus Socket 异常 ：https://learn.microsoft.com/en-us/azure/service-bus-messaging/service-bus-messaging-exceptions#cause-2
