On a (stoneage) Windows Mobile 5.0 device I have a problem with the following demo code:
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Net;
using System.Text;
using System.Threading;
namespace TaskTest1
{
class Program
{
static List<String> Urls = new List<String>()
{
"https://www.google.de",
"https://www.wikipedia.de",
"https://kjdsfhkjfkhls.de", //non-existent
"https://kjdsfhkfgddfgfjfkhls.de", //non-existent
"https://www.msdn.com", //repeated call to same address
"https://www.msdn.com" };
static string TimeStamp()
{
return DateTime.Now.ToString("hh:mm:ss.fff");
}
static void WriteLine(String S)
{
Console.WriteLine(String.Format("{0} {1}", TimeStamp(),S));
System.Diagnostics.Debug.WriteLine(String.Format("{0} {1}", TimeStamp(), S));
}
static void Test1Url(string Url)
{
WriteLine(String.Format("Testing: {0}",Url));
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);
request.Timeout = 2000;
try
{
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
if (response.StatusCode == HttpStatusCode.OK)
{
using (StreamReader reader = new StreamReader(response.GetResponseStream()))
{
long BytesRead = reader.ReadToEnd().Length;
WriteLine(String.Format("{0} responded with {1} bytes", Url, BytesRead));
}
}
else
{
WriteLine(String.Format("{0} returned error {1}", Url, response.StatusCode));
}
}
catch (System.Net.WebException e)
{
WriteLine(String.Format("Exception: call to {0} failed with error {1}", Url, e.Status));
}
}
static void Main(string[] args)
{
List<Thread> Threads = new List<Thread>();
// create one thread per url
foreach(String url in Urls)
{
Thread T = new Thread(() => Test1Url(url));
Threads.Add(T);
T.Start();
}
// Wait for all threads to complete
foreach (Thread T in Threads)
{
T.Join();
}
// ended by debugger
while (true) {};
}
}
}
What it should do is concurrently test some https connections, wait 2s for a response and log the outcome to the console.
On Windows 10, VS 2019, .net 4.x (but also if compiled against .net 2.0), the code gives the desired results:
11:54:00.222 Testing: https://www.google.de
11:54:00.232 Testing: https://www.wikipedia.de
11:54:00.237 Testing: https://kjdsfhkfgddfgfjfkhls.de
11:54:00.227 Testing: https://kjdsfhkjfkhls.de
11:54:00.273 Testing: https://www.msdn.com
11:54:00.224 Testing: https://www.msdn.com
11:54:00.557 Exception: call to https://kjdsfhkjfkhls.de failed with error NameResolutionFailure
11:54:00.565 Exception: call to https://kjdsfhkfgddfgfjfkhls.de failed with error NameResolutionFailure
11:54:00.687 https://www.wikipedia.de responded with 4205 bytes
11:54:00.776 https://www.google.de responded with 46759 bytes
11:54:00.940 Exception: call to https://www.msdn.com failed with error SendFailure
11:54:00.949 Exception: call to https://www.msdn.com failed with error SendFailure
On Windows Mobile, VS 2008, .net 2.0 I get
11:43:59.000 Testing: https://www.msdn.com
11:43:59.000 Testing: https://www.msdn.com
11:43:59.000 Testing: https://www.msdn.com
11:43:59.000 Testing: https://www.msdn.com
11:43:59.000 Testing: https://www.msdn.com
11:43:59.000 Testing: https://www.msdn.com
11:44:01.000 Exception: call to https://www.msdn.com failed with error Timeout
11:44:01.000 Exception: call to https://www.msdn.com failed with error Timeout
11:44:01.000 Exception: call to https://www.msdn.com failed with error Timeout
11:44:02.000 Exception: call to https://www.msdn.com failed with error Timeout
11:44:02.000 Exception: call to https://www.msdn.com failed with error Timeout
11:44:02.000 Exception: call to https://www.msdn.com failed with error Timeout
Sometimes, in very rare cases, I also have seen:
11:43:59.000 Testing: https://www.google.de
11:43:59.000 Testing: https://www.msdn.com
11:43:59.000 Testing: https://www.msdn.com
11:43:59.000 Testing: https://www.msdn.com
11:43:59.000 Testing: https://www.msdn.com
11:43:59.000 Testing: https://www.msdn.com
Seems that my Url string is not maintained correctly. There is a race condition, and the task tends to pick up the last string in the list.
What am I doing wrong?
