创建多个线程并等待它们全部完成，然后再次调用该线程

Question

I have a Web Service, to make the load of the database server for a local database, making 100 requests for records.

Since the process is slow, I want to create ten threads, not to use too much memory, making Web Service calls, and when one of the threads, finished, over 100 call records. How do part of the thread?

Example:

Create thread 1 Create thread 2 Create thread 3 Create thread 4

thread 1 complete change Web Service again

Edit

My code not working. Variable send always gets the value 10 and not 0,1,2,3,4 and etc.

Int32 page = 0;            
do
{                
    for (int iterator=0; iterator < 10; iterator++)
    {                    
        listTask[iterator] = Task.Factory.StartNew(() =>
        {
            Int32 send = iterator + page * 10;
            DoStatus("Page: " + send.ToString());
            Processamento(parametros, filial, send);                        
        });
    }

    Task.WaitAll(listTask);
    page++;

}
while (true); // Test only

Answer 1

You're closing over the loop variable. You need to remember that lambdas close over variables not over values . Your tasks will each read the value of iterator at the time that the lambda executes iterator + page * 10 . By the time that that happens the main thread has already incremented it to 10 .

This is simple enough to resolve. Make a copy of the loop variable inside of your for loop so that the closure closes over that variable, which never changes.

for (int iterator=0; iterator < 10; iterator++)
{
    int i = iterator;
    listTask[iterator] = Task.Factory.StartNew(() =>
    {
        Int32 send = i + page * 10;
        DoStatus("Page: " + send.ToString());
        Processamento(parametros, filial, send);                        
    });
}

Answer 2

If I understand your question, you want to create 10 threads, wait for all, then recreate 10 threads, etc. Each thread load 100 results.

In this answer, results are String but that can be changed.

private void Load()
{
    Boolean loading = true;
    List<String> listResult = new List<String>();
    Int32 boucle = 0;

    Task[] listTask = new Task[10];

    do
    {
        // create 10 threads (=1000 results)
        for (int iterator=0; iterator < 10; iterator++)
        {
            // [0-99] [100-199] [200-299] ...
            Int32 start = 100 * iterator + 1000 * boucle;
            Int32 end = start + 99;

            listTask[iterator] = Task<List<String>>.Factory.StartNew(() =>
            {
                List<String> data = LoadData(start, end);
                return data;
            });
        }

        // wait for 10 threads to finish
        Task.WaitAll(listTask);

        // collapse results
        for (int i=0; i < 10; i++)
        {
            listResult.AddRange((listTask[i] as Task<List<String>>).Result);
        }

        // check if there is 100 results in last thread
        loading = (listTask[9] as Task<List<String>>).Result.Count == 100;

        // ready for another iteration (next 1000 results)
        boucle++;
    }
    while (loading);
}

private List<string> LoadData(int p1, int p2)
{
    // TODO : load data from p1 to p2
    throw new NotImplementedException();
}