Entity Framework lazy loading doesn't work from other thread
- by Thomas Levesque
Hi,
I just found out that lazy loading in Entity Framework only works from the thread that created the ObjectContext. To illustrate the problem, I did a simple test, with a simple model containing just 2 entities : Person and Address. Here's the code :
private static void TestSingleThread()
{
using (var context = new TestDBContext())
{
foreach (var p in context.Person)
{
Console.WriteLine("{0} lives in {1}.", p.Name, p.Address.City);
}
}
}
private static void TestMultiThread()
{
using (var context = new TestDBContext())
{
foreach (var p in context.Person)
{
Person p2 = p; // to avoid capturing the loop variable
ThreadPool.QueueUserWorkItem(
arg =>
{
Console.WriteLine("{0} lives in {1}.", p2.Name, p2.Address.City);
});
}
}
}
The TestSingleThread method works fine, the Address property is lazily loaded. But in TestMultiThread, I get a NullReferenceException on p2.Address.City, because p2.Address is null.
It that a bug ? Is this the way it's supposed to work ? If so, is there any documentation mentioning it ? I couldn't find anything on the subject on MSDN or Google...
And more importantly, is there a workaround ? (other than explicitly calling LoadProperty from the worker thread...)
Any help would be very appreciated
PS: I'm using VS2010, so it's EF 4.0. I don't know if it was the same in the previous version of EF...
