Tips on my multi-threading intuition?

Question

I wrote a program to copy a .doc template, add some text to it, then save and close it. I have to do this many times, and saving and closing a word document is slow. I decided to use multi-threading, but I'm a noob at this stuff and just wrote what came to me. Any feedback would be greatly appreciated (on any aspect, not just the multi-threading).

Here is my code for a task:

public Task
{
    public string Value;
    public bool HasRun;
    public Task(string value)
    {
        Value = value;
        HasRun = false;
    }
}

I create a list of Tasks that is a class level variable, accessible by all threads:

Tasks = db.table.select(a => new Task(a.value)).ToList();

Next, I run the following in each thread:

while(tasks.Any(a => a.HasRun == false))
{
    var value = "";
    lock(tasks)
    {
        var task = tasks.Where(a => a.HasRun == false).First();
        value = task.Value;
        task.HasRun = true;   
    }

    CreateNewDocumentAppendValueAndSave(value);
}

Answer 1

Let the framework do multithreading for you:

List<string> tasks = new List<string>();
foreach (string value in db.table.select(a => a.value))
{
    tasks.Add(Task.Factory.StartNew(() => CreateNewDocumentAppendValueAndSave(value)));
}
Task.WaitAll(tasks.ToArray());

Where Task is System.Threading.Tasks.Task.

Answer 2

Until we know your answers to Alex and svick's questions, here's a recommendation I have. I would change your loop slightly to this so that you only get the next task to run once per loop instead of twice.

I also normally name my variables used in LINQ expressions based on the variable being iterated through, so in this loop I've also renamed the a to t. I find it easier to read when the inner variable reflects what the outer variable is.

var task = tasks.FirstOrDefault(t => !t.HasRun);
while (task != null)
{
    var value = "";
    lock (tasks)
    {
        value = task.Value;
        task.HasRun = true;
    }

    CreateNewDocumentAppendValueAndSave(value);

    task = tasks.FirstOrDefault(t => !t.HasRun);
}