CODEWITHSUNDEEP
c#.netmultithreadinghttpwebrequestthreadpool
sora0419
sora0419

Reputation: 2378

Wait Till All Thread Finish Processing Each WebRequest

I am building a threading program in C# .Net4.0 and I ran into some issue.

I am using threadpool and callback. Below is my code in Main().

string[] urls = { url1, url2, url3, url4 };
callBack = new WaitCallback(PooledFunc);
for (int i = 0; i < urls.Length; i++)
    ThreadPool.QueueUserWorkItem(callBack, urls[i]);

I also have a function that will get response from the urls

static void PooledFunc(object url)
{
    HttpWebRequest request = HttpWebRequest.Create(url) as HttpWebRequest;

    // Get the response.
    HttpWebResponse response = (HttpWebResponse)request.GetResponse();
    Stream Answer = response.GetResponseStream();

    // Display the status.
    Console.WriteLine(response.Headers);
    StreamReader _Answer = new StreamReader(Answer);

    string content = _Answer.ReadToEnd();
    Console.WriteLine(content);
}

I put some test prints in there, and with the above code, the program looks like it started all threads but terminate before all of them went through, and everytime is different.

When I put Console.ReadLine(); after the for loop, then it looks like it waits till all threads are done.

Question: Is there a way I can wait till all threads are finished then proceed to the next step without using Console.ReadLine(); ?

Upvotes: 0

Views: 598

Answers (1)

Reed Copsey
Reed Copsey

Reputation: 564373

Instead of using ThreadPool.QueueUserWorkItem, you could use Parallel.ForEach to accomplish the same thing:

string[] urls = { url1, url2, url3, url4 };
Parallel.ForEach(urls, url => PooledFunc(url));

Parallel.ForEach will not return until all of the items have been processed.

This also allows you to keep the PooledFunc declaration nicer:

static void PooledFunc(string url) // Can keep this strongly typed
{
    HttpWebRequest request = HttpWebRequest.Create(url) as HttpWebRequest;

Upvotes: 2

Related Questions