MSDTC, Transaction, Context and Threads

[Gian Paolo Clarici]

I've a problem using multithreading and MTS.
I'm using framework 1.1

Basically I want, from the Main Thread , to start a (distributed)
transaction.
then I want to start 2 new threads to perform some Database operations, each
thread will do some work on the DB using its own SQLConnection.
I want the 2 SQLConnections of the two threads partecipate to the same
(distributed) transaction.
The problem is that i do not know how to propagate the Object Context from
the Main thread to the 2 subThreads.



I start a new Transactional Context from the Main Thread with the following
code:


sc = new ServiceConfig();
sc.Transaction = TransactionOption.Required;
ServiceDomain.Enter(sc);


Then I run two Threads that will open two distinct SQLConnections
to perform some work at the same time .


ClasseTest CTest1 = new ClasseChiamata.ClasseTest() ;
ClasseTest CTest2 = new ClasseChiamata.ClasseTest() ;

Thread workThread1 = new Thread (new ThreadStart(CTest1.EseguiOp));
workThread1.Start();

Thread workThread2 = new Thread (new ThreadStart(CTest2.EseguiOp));
workThread2.Start();

workThread1.Join();
workThread2.Join();


The problem is that the SQLConnection created inside the method:
CTest2.EseguiOp()

is not automatically enlisted in the (Distributed)Transaction created before
the methods have been invoked asynchronously.

All works fine if I invoke the method synchronously, while if I use
multithreading to recall
the same method, the MTS object Context is not available to the subThreads.

Do you know how to pass the MTS Context to the 2 subThreads?


this is the code of the method that I want to recall asynchronously:


using System;
using System.Data;
using System.EnterpriseServices;
using System.Data.SqlClient;

namespace ClasseChiamata
{


public class ClasseTest
{

public bool hasError = false;
private SqlConnection mySqlConnection;

public ClasseTest()
{
}


public void EseguiOp()
{
try
{

mySqlConnection = new SqlConnection
("database=TEST;server=localhost;Persist Security
Info=False;uid=sa;pwd=xxxx");

SqlCommand mySqlCommand = new SqlCommand();

mySqlConnection.Open();
//mySqlConnection.EnlistDistributedTransaction(trans);

mySqlCommand.Connection = mySqlConnection;
mySqlCommand.CommandText = "UPDATE Table1 SET Description = 'AAA' WHERE
Code = 'A1'";
mySqlCommand.ExecuteNonQuery();



ContextUtil.SetAbort(); // this will work in synchronous mode, but will
fail if recalled in a secondary thread, with the error "there is no MTS
object Context"!



}
catch(System.Exception ex)
{
hasErrore = true;
}

}

}
}





the line that fails is the

ContextUtil.SetAbort(); // this will work in synchronous mode, but will
fail if recalled in a secondary thread, with the error "there is no MTS
object Context"!


any help will be apreciated!

JPC

 

[Frans Bouma [C# MVP]]

I've a problem using multithreading and MTS.
I'm using framework 1.1

Basically I want, from the Main Thread , to start a (distributed)
transaction.
then I want to start 2 new threads to perform some Database
operations, each thread will do some work on the DB using its own
SQLConnection. I want the 2 SQLConnections of the two threads
partecipate to the same (distributed) transaction.
The problem is that i do not know how to propagate the Object Context
from the Main thread to the 2 subThreads.

I start a new Transactional Context from the Main Thread with the
following code:


sc = new ServiceConfig();
sc.Transaction = TransactionOption.Required;
ServiceDomain.Enter(sc);


Then I run two Threads that will open two distinct SQLConnections
to perform some work at the same time .


ClasseTest CTest1 = new ClasseChiamata.ClasseTest() ;
ClasseTest CTest2 = new ClasseChiamata.ClasseTest() ;

Thread workThread1 = new Thread (new
ThreadStart(CTest1.EseguiOp)); workThread1.Start();

Thread workThread2 = new Thread (new
ThreadStart(CTest2.EseguiOp)); workThread2.Start();

workThread1.Join();
workThread2.Join();


The problem is that the SQLConnection created inside the method:
CTest2.EseguiOp()

is not automatically enlisted in the (Distributed)Transaction created
before the methods have been invoked asynchronously.

All works fine if I invoke the method synchronously, while if I use
multithreading to recall
the same method, the MTS object Context is not available to the
subThreads.

Do you know how to pass the MTS Context to the 2 subThreads?
any help will be apreciated!

Your threads have to be marked as MTA, multithreadedapartments. You've
to check the ApartmentState of the thread objects. Still, I'm with you
that it's unclear how to do this. Browsing through the docs I ran into
quite a view inconsistencies, so I'm sorry but I can't give you a clear
answer, other than that the threading model of your threads has to be
MTA, not STA.

FB

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