Static Methods and Their Variables - .NET 1.1

One of a series of posts from andraszek.net posted originally between 2006 and 2010. 

Have you ever wondered about local variables of static methods? Are they static too? Or are they call-specific? What happens with the variables when a second thread calls the method while the first has not finished executing it yet? The code below allows examining this.

// You may need to run this C# .NET console application 
// a few times before you get interesting results
// Have fun!
using System;
using System.Threading;

namespace Andraszek.net
{
  class StaticMethodExample
  {
    public static void ShowXTwice ()
    {
      // Uncomment the line below to see what happens if only one thread at 
      // a time is allowed to use type StaticMethodExample
      // Observe the average number of ticks go up
      //lock (typeof(StaticMethodExample))
      {
      Random r = new Random();
      // Although the ShowXTwice method is static, each thread has its own instance of x
      // otherwise, all threads would use the same variable
      // and as a result sometimes x would have a different value when checked for the 
      // second time.
      // For example: x checked for the first time by thread 1 (x=123), then thread 2 
      // assigns a new value to x (x=456), and now thread 1 checks x for the second time
      // 
      int x = r.Next(1, 10000); 
      Console.WriteLine(Thread.CurrentThread.Name 
        + " Checking x for the first time:  " + x.ToString());
      Console.WriteLine(Thread.CurrentThread.Name 
        + " Checking x for the second time:  " + x.ToString());
      }
    }
  }

  class TestStaticMethodExample 
  {
    public static void Main() 
    {
      int maxThreads = 100;
      Thread[] threads = new Thread[maxThreads];
      for (int i = 0; i < maxThreads; i++) 
      {
        Thread t = new Thread(
                       new ThreadStart(StaticMethodExample.ShowXTwice));
        t.Name = "Thread " + i.ToString();
        threads[i] = t;
      }
      long startTicks = DateTime.Now.Ticks;
      for (int i = 0; i < maxThreads; i++) 
      {
        threads[i].Start();
      }

      // wait for all threads to finish
      for (int i = 0; i < maxThreads; i++) 
      {
        threads[i].Join();
      }
      long endTicks = DateTime.Now.Ticks;

      Console.Write("Number of ticks from start to end: ");
      Console.WriteLine(endTicks - startTicks);
      Console.WriteLine("Press Enter");
      Console.ReadLine();
    }
  }
}

		

Here is the output: