如何同步访问数据库，一次一个线程

Question

I have developed a Windows Service in C# that receives events from an external hardware. For each received event, a SQLite database creates a record and save it.

The problem is that from time to time, a DBLock error occurs, so I need to control that only one thread can write to the database at a time.

I have created this class variable that is instantiated in Service OnStart method:

private DataWare.monitorEntities _db;

Then, in the event, I have:

void driver_Transaccion(object sender, AttendanceReader.MarcacionEventArgs e)
{
      lock (_db)
      {
          /* Code that creates a record a does some other actions */
          /* ......... */
          _db.SaveChanges();
      }
}

The problem is that I continue receiving the DBLock exception, so, it seems the instruction lock (_db) is not taken into account.

Any help, please?

Answer 1

Are you disposing your connection after usage?

lock (_lockObj)
{
    using (MyEntities context = new MyEntities)
    {
        // do stuff
        context.SaveChanges();
    }
}