服务ASP.NET Web-API HTTP请求涉及多少个线程？

Question

I thought to log Thread-ID for the purpose of tracking a request and make the log file readable.

So, my initial attempts were logging in Global.asax like this:

protected void Application_BeginRequest()
{
    log4net.ILog writer = log4net.LogManager.GetLogger(this.GetType());
    writer.InfoFormat("Gotta service a request. Id = {0}", System.Threading.Thread.CurrentThread.ManagedThreadId);
}

protected void Application_EndRequest()
{
    log4net.ILog writer = log4net.LogManager.GetLogger(this.GetType());
    writer.InfoFormat("Completed servicing a request. Id = {0}", System.Threading.Thread.CurrentThread.ManagedThreadId);
}

But when I see the log-file, it is very strange.

2014-06-16 20:27:06,018 -  Gotta service a request. Id = 286 --> From Application_BeginRequest()
2014-06-16 20:27:06,042 - Servicing Request Thread-Id = 286 --> this message comes from controller
2014-06-16 20:27:06,043 - Thread-Id = 286 --> this message comes from controller
2014-06-16 20:27:06,237 - Completed servicing a request. Id = 287 --> From Application_EndRequest()

In Application_Start , the Thread-Id is 286 but when it comes back to Application_EndRequest , the Thread-Id changed to 287 .

Is it not one thread that services the entire HTTP request ?

Any ideas why ?

Answer 1

The request is processed single threaded, but that does not mean it is the same thread throughout the request.

The request can "hop" threads, you are still guaranteed the execution happens in order but you are not guaranteed to run on the same thread throughout.