CODEWITHSUNDEEP
c#.netmultithreadingentity-framework
user1115198
user1115198

Reputation: 31

EF context and multi-threading

I was wondering if somebody explain me what is wrong in my code. I run timer in extra thread. In timer function I work with EF context. I see that timer function has worked 6 times and I especially set interval in 3 seconds and take only 100 rows but in my DB I see only one work. So where is my error?

namespace WindowsFormsApplication2
{
    public partial class Form1 : Form
    {
        private static int cnt = 0;
        private Thread thread;

        public Form1()
        {
            InitializeComponent();
        }

        private  void StartThread()
        {
            var timer = new System.Timers.Timer();
            timer.Elapsed += new System.Timers.ElapsedEventHandler(ProcessDb);
            timer.Interval = 3000;
            timer.Start();
        }

        public void ProcessDb(object sender, System.Timers.ElapsedEventArgs e)
        {
            cnt++;
            ConnService serv = new ConnService();
            serv.UpdateConnections(cnt);
        }

        private void button1_Click(object sender, EventArgs e)
        {
            thread = new Thread(StartThread);
            thread.Start();

            Thread.Sleep(20000);
        }
    }

    public class MyqQueue
    {
        public static Stack<int> myStack = new Stack<int>();
        public static Stack<int> myStack2 = new Stack<int>();
    }
}

namespace WindowsFormsApplication2
{
    class ConnService
    {
        public ConnService()
        {
            cnt++;
        }

        private static int cnt;
        public void UpdateConnections(int second)
        {
            MyqQueue.myStack.Push(second);

            DjEntities ctx = new DjEntities();
            var entities = ctx.Connections.Take(100).Where(c => c.State == null);
            foreach (var connection in entities)
            {
                connection.State = second;
            }
            if (second == 1)
                Thread.Sleep(7000);

            MyqQueue.myStack2.Push(second);
            ctx.SaveChanges();
        }
    }
}

Upvotes: 3

Views: 466

Answers (1)

Akash Kava
Akash Kava

Reputation: 39956

 ctx.Connections.Take(100).Where(c => c.State == null)

Should be changed to

 ctx.Connections.Where(c => c.State == null).Take(100)

Your first query translates to first take 100 without filtering and then apply filter.

Second query I have written will take items filtered and then take top 100.

Upvotes: 1

Related Questions