Hello,
we are using CTP5 together with Workflow Foundation - in our scenario it means multiple DbContext instances in multiple threads (and multiple exceptions ;-).
To reproduce theese exception we've done the following:
1.) Our business object:
public class Data
{
public int Id { get; set; }
public string Text { get; set; }
}
2.) Our DbContext:
public class Context : DbContext
{
public Context(string connectionString)
: base(connectionString)
{}
public DbSet<Data> Datas { get; set; }
}
3.) Our code:
Parallel.ForEach(Enumerable.Range(1, 10), i =>
{
using (Context context = new Context("Data Source=(local);Initial Catalog=EFTEST;Integrated Security=true"))
{
Console.WriteLine("{0}: {1}", i, context.Datas.Where(d => d.Id % i == 0).Count());
}
});
This results in an System.AggregateException.
Encapsulation the new Context(...) line with a lock statement is no solution - the exception still appears. The model creation seems to be a async operation.
For now we solves the problem with a dirty trick:
public class Context : DbContext
{
private static readonly object locker = new object();
public Context(string connectionString)
: base(connectionString)
{
lock (locker)
{
this.ChangeTracker.DetectChanges();
}
}
public DbSet<Data> Datas { get; set; }
}
What is the right strategy for this problem ?
Best regards Matthias
