multithread - waiting for threads

Question

I've used the background worker a few times, but haven't really worked with multithreading.

I have a program that reads in 3 files, each to a table, then validates the data in each table before working with all 3 tables together.  The validation takes a long time, so I'd like each table to validate its data at the same time.  Once the validation is done the program can continue in a single thread to work with the 3 tables together.

Here's a sample of what my method looks like.

public void FixData(string File1, string File2, string File3)
{
   DataTable dt1 = CreateTableFromFile(File1);
   DataTable dt2 = CreateTableFromFile(File2);
   DataTable dt3 = CreateTableFromFile(File3);

   //run these 3 in seperate threads
   ValidateData(dt1);
   ValidateData(dt2);
   ValidateData(dt3);
   
   //once the validation threads are done continue
   DataTable dtPrintable = CombineData(dt1, dt2, dt3);
   
   OutputData(dtPrintable);
}

Thanks in advance,

Scott

Answer 1

Do it this way:

        public void FixData(string File1, string File2, string File3)
        {
            DataTable dt1 = CreateTableFromFile(File1);
            DataTable dt2 = CreateTableFromFile(File2);
            DataTable dt3 = CreateTableFromFile(File3);

            //run these 3 in seperate threads
            new Thread(new ParameterizedThreadStart(ValidateData)).Start(dt1);
            new Thread(new ParameterizedThreadStart(ValidateData)).Start(dt2);
            new Thread(new ParameterizedThreadStart(ValidateData)).Start(dt3);

            //once the validation threads are done continue
            //DataTable dtPrintable = CombineData(dt1, dt2, dt3);
            //OutputData(dtPrintable);
        }

        private DataTable CreateTableFromFile(string file)
        {
            DataTable table = new DataTable();
            //creating table..
            return table;
        }

        private void ValidateData(object obj)
        {
            DataTable table = (DataTable)obj;
            //do your work here...
        }

---

Mitja

Answer 2

You'll want to store the Thread returned from 'new Thread' and call join on all three of them after starting all three.  Join() will block until that thread is done executing.