C#

void QueueThreads(IEnumerable myCollection, uint maxThreads)
{
    uint usedThreads = 0;
    AutoResetEvent[] autoEvents = new AutoResetEvent[Math.Min(maxThreads, myCollection.Count)];
    
    foreach (T myObject in myCollection)
    {
        if (usedThreads < maxThreads)
        {
            autoEvents[usedThreads] = new AutoResetEvent(false);
            //Start a DoWork() thread, passing myObject and autoEvents[usedThreads]
            usedThreads++;
        }
        else
        {
            uint freeThreadID = WaitHandle.WaitAny(autoEvents);
            usedThreads--;
            //Start a DoWork() thread, passing myObject and autoEvents[freeThreadID]
            usedThreads++;
        }
    }
    WaitHandle.WaitAll(autoEvents);
}

void DoWork(myObject, AutoResetEvent are)
{
    //Do stuff with myObject
    //Save results to file/database
    are.Set()
}

void QueueThreads(IEnumerable myCollection, uint maxThreads)
{
    uint usedThreads = 0;
    IEnumerator myCollectionEnum = myCollection.GetEnumerator();
    
    for (uint i = 0; i <= Min(myCollection.Count,maxThreads); i++)
    {
        //Start a DoWork() thread, passing myCollectionEnum
    }
    //Find some way to wait until all threads are done
    myCollectionEnum.Reset();
}

void DoWork(IEnumerator myColEn)
{
    do
    {
        T myObject;
        lock (myColEn)
        {
            if (myColEn.MoveNext())
            {
                myObject = myColEn.Current
            }
            else
            {
                break;
            }
        }
        
        //Do stuff with myObject
        //Save results to file/database
    }
}

List<int> ints;
int[] indices;
List<int> slected = ints select items at 'indices';