Question: I was wondering how you would use the TransactionScope class in the correct way when you are dealing with multithreading?

We create a new scope in our main thread and then we spawn off a couple of worker threads and we want these to participate in the main scope, so that for example the rollback is called on each worker if the scope is never completed.

I read something about TransactionScope using the ThreadStaticAttribute internally which made the above impossible / very difficult - could someone verify either way? If we run our code in a synchronized fashion then the rollbacks work, i.e the inner transactions are able to participate in the main transaction, but not if we switch over to a threaded execution.

Answer: 
See [MSDN](http://msdn.microsoft.com/en-us/library/system.transactions.transactionscope.aspx):

> 
> You should also use the TransactionScope and
>  DependentTransaction class for
>  applications that require the use of
>  the same transaction across multiple
>  function calls or multiple thread
>  calls.
> 
> 
> 

So maybe look into `DependentTransaction` - in particular, there is a worker thread example, [here](http://msdn.microsoft.com/en-us/library/system.transactions.dependenttransaction.aspx).
This is correct: the `TransactionScope` class uses the `Transaction.Current` property that stores its value in the field, which is marked with the `ThreadStatic` attribute.

The `ThreadStatic` attribute makes sure that the field value gets thread affinity, i.e. it has unique value in each thread. It's the recommended approach to share data *within* a thread. It's also known as [Thread Local Storage](http://en.wikipedia.org/wiki/Thread-Specific_Storage) (TLS).

The `TransactionScope` class just defines a transaction context in the current thread. It doesn't mean, however, that *your* code must accomplish all the job in that thread. I could imagine a complex calculation algorithm that uses multiple threads.