Imports System
Imports System.IO
Imports System.Security.Permissions
Imports System.Threading

' Request permission to create and write files to C:\TestTest.
<Assembly: FileIOPermissionAttribute(SecurityAction.RequestMinimum, _
     All := "C:\TestTest")>

Public Class Test

    ' WaitHandle.WaitAll requires a multithreaded apartment 
    ' when using multiple wait handles.
    <MTAThreadAttribute> _
    Shared Sub Main()
        Const numberOfFiles As Integer = 5
        Dim dirName As String = "C:\TestTest"
        Dim fileName As String 

        Dim byteArray() As Byte 
        Dim randomGenerator As New Random()

        Dim manualEvents(numberOfFiles - 1) As ManualResetEvent
        Dim stateInfo As State 

        If Directory.Exists(dirName) <> True Then
            Directory.CreateDirectory(dirName)
        End If

        ' Queue the work items that create and write to the files.
        For i As Integer = 0 To numberOfFiles - 1
            fileName = String.Concat( _
                dirName, "\Test", i.ToString(), ".dat")

            ' Create random data to write to the file.
            byteArray = New Byte(1000000){}
            randomGenerator.NextBytes(byteArray)

            manualEvents(i) = New ManualResetEvent(false)

            stateInfo = _ 
                New State(fileName, byteArray, manualEvents(i))

            ThreadPool.QueueUserWorkItem(AddressOf _
                Writer.WriteToFile, stateInfo)
        Next i

        ' Since ThreadPool threads are background threads, 
        ' wait for the work items to signal before exiting.
        WaitHandle.WaitAll(manualEvents)
        Console.WriteLine("Files written - main exiting.")
    End Sub

End Class

' Maintain state to pass to WriteToFile.
Public Class State

    Public fileName As String
    Public byteArray As Byte()
    Public manualEvent As ManualResetEvent

    Sub New(fileName As String, byteArray() As Byte, _
        manualEvent As ManualResetEvent)

        Me.fileName = fileName
        Me.byteArray = byteArray
        Me.manualEvent = manualEvent
    End Sub

End Class

Public Class Writer

    Private Sub New()
    End Sub

    Shared workItemCount As Integer = 0

    Shared Sub WriteToFile(state As Object)
        Dim workItemNumber As Integer = workItemCount
        Interlocked.Increment(workItemCount)
        Console.WriteLine("Starting work item {0}.", _
            workItemNumber.ToString())
        Dim stateInfo As State = CType(state, State)
        Dim fileWriter As FileStream = Nothing

        ' Create and write to the file.
        Try
            fileWriter = New FileStream( _
                stateInfo.fileName, FileMode.Create)
            fileWriter.Write(stateInfo.byteArray, _
                0, stateInfo.byteArray.Length)
        Finally
            If Not fileWriter Is Nothing Then
                fileWriter.Close()
            End If

            ' Signal Main that the work item has finished.
            Console.WriteLine("Ending work item {0}.", _
                workItemNumber.ToString())
            stateInfo.manualEvent.Set()
        End Try
    End Sub

End Class

using System;
using System.IO;
using System.Security.Permissions;
using System.Threading;

// Request permission to create and write files to C:\TestTest.
[assembly: FileIOPermissionAttribute(SecurityAction.RequestMinimum, 
     All = @"C:\TestTest")]

class Test
{
    static void Main()
    {
        const int numberOfFiles = 5;
        string dirName = @"C:\TestTest";
        string fileName;

        byte[] byteArray;
        Random randomGenerator = new Random();

        ManualResetEvent[] manualEvents = 
            new ManualResetEvent[numberOfFiles];
        State stateInfo;

        if(!Directory.Exists(dirName))
        {
            Directory.CreateDirectory(dirName);
        }

        // Queue the work items that create and write to the files.
        for(int i = 0; i < numberOfFiles; i++)
        {
            fileName = string.Concat(
                dirName, @"\Test", i.ToString(), ".dat");

            // Create random data to write to the file.
            byteArray = new byte[1000000];
            randomGenerator.NextBytes(byteArray);

            manualEvents[i] = new ManualResetEvent(false);

            stateInfo = 
                new State(fileName, byteArray, manualEvents[i]);

            ThreadPool.QueueUserWorkItem(new WaitCallback(
                Writer.WriteToFile), stateInfo);
        }

        // Since ThreadPool threads are background threads, 
        // wait for the work items to signal before exiting.
        WaitHandle.WaitAll(manualEvents);
        Console.WriteLine("Files written - main exiting.");
    }
}

// Maintain state to pass to WriteToFile.
class State
{
    public string fileName;
    public byte[] byteArray;
    public ManualResetEvent manualEvent;

    public State(string fileName, byte[] byteArray, 
        ManualResetEvent manualEvent)
    {
        this.fileName = fileName;
        this.byteArray = byteArray;
        this.manualEvent = manualEvent;
    }
}

class Writer
{
    static int workItemCount = 0;
    Writer() {}

    public static void WriteToFile(object state)
    {
        int workItemNumber = workItemCount;
        Interlocked.Increment(ref workItemCount);
        Console.WriteLine("Starting work item {0}.",
            workItemNumber.ToString());
        State stateInfo = (State)state;
        FileStream fileWriter = null;

        // Create and write to the file.
        try
        {
            fileWriter = new FileStream(
                stateInfo.fileName, FileMode.Create);
            fileWriter.Write(stateInfo.byteArray, 
                0, stateInfo.byteArray.Length);
        }
        finally
        {
            if(fileWriter != null)
            {
                fileWriter.Close();
            }

            // Signal Main that the work item has finished.
            Console.WriteLine("Ending work item {0}.", 
                workItemNumber.ToString());
            stateInfo.manualEvent.Set();
        }
    }
}

using namespace System;
using namespace System::IO;
using namespace System::Security::Permissions;
using namespace System::Threading;

// Request permission to create and write files to C:\TestTest.
// Maintain state to pass to WriteToFile.

[assembly:FileIOPermissionAttribute(SecurityAction::RequestMinimum,
All="C:\\TestTest")];
ref class State
{
public:
   String^ fileName;
   array<Byte>^byteArray;
   ManualResetEvent^ manualEvent;
   State( String^ fileName, array<Byte>^byteArray, ManualResetEvent^ manualEvent )
      : fileName( fileName ), byteArray( byteArray ), manualEvent( manualEvent )
   {}

};

ref class Writer
{
private:
   static int workItemCount = 0;
   Writer(){}


public:
   static void WriteToFile( Object^ state )
   {
      int workItemNumber = workItemCount;
      Interlocked::Increment( workItemCount );
      Console::WriteLine( "Starting work item {0}.", workItemNumber.ToString() );
      State^ stateInfo = dynamic_cast<State^>(state);
      FileStream^ fileWriter;

      // Create and write to the file.
      try
      {
         fileWriter = gcnew FileStream( stateInfo->fileName,FileMode::Create );
         fileWriter->Write( stateInfo->byteArray, 0, stateInfo->byteArray->Length );
      }
      finally
      {
         if ( fileWriter != nullptr )
         {
            fileWriter->Close();
         }

         // Signal main() that the work item has finished.
         Console::WriteLine( "Ending work item {0}.", workItemNumber.ToString() );
         stateInfo->manualEvent->Set();
      }

   }

};

void main()
{
   const int numberOfFiles = 5;
   String^ dirName =  "C:\\TestTest";
   String^ fileName;
   array<Byte>^byteArray;
   Random^ randomGenerator = gcnew Random;
   array<ManualResetEvent^>^manualEvents = gcnew array<ManualResetEvent^>(numberOfFiles);
   State^ stateInfo;
   if (  !Directory::Exists( dirName ) )
   {
      Directory::CreateDirectory( dirName );
   }


   // Queue the work items that create and write to the files.
   for ( int i = 0; i < numberOfFiles; i++ )
   {
      fileName = String::Concat( dirName,  "\\Test", ((i)).ToString(),  ".dat" );

      // Create random data to write to the file.
      byteArray = gcnew array<Byte>(1000000);
      randomGenerator->NextBytes( byteArray );
      manualEvents[ i ] = gcnew ManualResetEvent( false );
      stateInfo = gcnew State( fileName,byteArray,manualEvents[ i ] );
      ThreadPool::QueueUserWorkItem( gcnew WaitCallback( &Writer::WriteToFile ), stateInfo );

   }

   // Since ThreadPool threads are background threads, 
   // wait for the work items to signal before exiting.
   WaitHandle::WaitAll( manualEvents );
   Console::WriteLine( "Files written - main exiting." );
}