Visual Basic

22-Jan-07 18:48

Hi,

I am working on a project that uses a VB.NET application for sending e-mails. This application works as a scheduler and is scheduled to start after every 1 min. It works as follows:
1. It picks up the projects that are scheduled to run(send mails).
2. It picks up the contacts to which the mail needs to be sent.
3. It sends the mail.
Now I have used threading so that each project picked up in the 1st step is executed as a different thread. Now the problem is that when the scheduler starts again after 1 min, the projects picked by this instance have to wait for completion of all the threads belonging to the previous instance. I want these new threads to also start concurrently with the previous threads that are already running.

Any suggestions on this will be highly appretiated.

regards,
Sandeep

Christian Graus22-Jan-07 18:52

22-Jan-07 18:52

Perhaps if you can't finish the task in a minute, you need to run it less often ? I mean, you can't get more speed out of having all those threads, the older ones will just wait longer, for the ones that have been started.

You can create all the threads you want, that's not an issue. But, I wonder how many is practical.

Christian Graus - C++ MVP

'Why don't we jump on a fad that hasn't already been widely discredited ?' - Dilbert

Sandeep_S22-Jan-07 19:07

22-Jan-07 19:07

Hi,

Thanks for the reply but why it is happening that threads(say 4 project threads) belonging to the one instance of the scheduler(our application) and other threads belonging to separate instance(2nd instance that will be created after 1 minute), what exactly prevents threads from 2nd instance to start.Is there any background and foreground threads kind of issue.

Regards
Sandeep

Christian Graus22-Jan-07 19:54

22-Jan-07 19:54

Nothing, I don't see how that is possible. What makes you think it's the case ? Why is it running twice ? How many instances will be running, over time ?

Christian Graus - C++ MVP

'Why don't we jump on a fad that hasn't already been widely discredited ?' - Dilbert

Sandeep_S22-Jan-07 20:05

22-Jan-07 20:05

Let me explain:
Suppose the scheduler runs for the first time and it picks 5 projects(5 threads). Supposing each project has 1000 contacts to whom the mail needs to be sent.
Now the scheduler is scheduled to run after every 1 min. So after 1 min the second instance of the scheduler starts and it picks 5 more projects(5 more threads). Now these new threads keep on waiting till the mails are sent to the contacts of first 5000 contacts. It is only after these mails are sent the threads in the second instance start.
Our system sends about 600 mails in a minute. Even if the mails are not sent for the previous instance the threads in the second instance should atleast start.

Christian Graus22-Jan-07 20:09

22-Jan-07 20:09

OK, it sounds like the mail class can only send one mail at a time ( which seems possible ). So, as I said, the question is, why does it have to run every minute ?

Christian Graus - C++ MVP

'Why don't we jump on a fad that hasn't already been widely discredited ?' - Dilbert

Sandeep_S22-Jan-07 20:28

22-Jan-07 20:28

We need to run it quite frequently because the projects added by our clients should be serviced as soon as they are added.
Even if we increase the time of executing the scheduler it may solve the problem temporarily. But my point is why should the threads wait, I mean this should not happen (conceptually atleast!).

Christian Graus22-Jan-07 20:35

22-Jan-07 20:35

Sandeep_S wrote:
We need to run it quite frequently because the projects added by our clients should be serviced as soon as they are added.

If they wait more than 60 seconds, the world will end ?

Really, you should have a single queue, which gets added to, not several queues. It seems to me that the answer is almost certainly that your method of sending emails is written this way, so a single queue is formed, even if you didn't impliment your app this way.

Christian Graus - C++ MVP

'Why don't we jump on a fad that hasn't already been widely discredited ?' - Dilbert

Sandeep_S22-Jan-07 20:50

22-Jan-07 20:50

This is the way we have implemented the app:

Dim objThreadList As ArrayList
Sub Main()
Schedule()
End Sub

Public Sub Schedule()
For Counter = 0 To dsProject.Tables(0).Rows.Count - 1 ''Loop runs for each project
CallThread(dsProject.Tables(0).Rows(Counter), Counter)
Next
End Sub

Public Sub CallThread(ByVal drProject As DataRow, ByVal counter As Integer)
objThreadList.Add(New Thread(AddressOf ThreadProcess))
drThread = drProject
objThreadList(counter).Start()
End Sub

Public Sub ThreadProcess()
Dim objClsProject As New clsProjectThread
objClsProject.ActualProcess()
End Sub

Public Sub ActualProcess()
'Code for sending mail
End Sub

Christian Graus22-Jan-07 20:56

22-Jan-07 20:56

I don't see how that proves anything. Like I said, it seems to me like the code for sending emails is forming a queue of mails to send. The mails from the first thread, get sent first.

Christian Graus - C++ MVP

'Why don't we jump on a fad that hasn't already been widely discredited ?' - Dilbert

Guffa22-Jan-07 19:16

Guffa

22-Jan-07 19:16

Sandeep_S wrote:
the projects picked by this instance have to wait for completion of all the threads belonging to the previous instance

Why?

---
Year happy = new Year(2007);

Sandeep_S22-Jan-07 19:19

22-Jan-07 19:19

Guffa wrote:
Why?

That's what I can't figure out.

Guffa22-Jan-07 19:43

Guffa

22-Jan-07 19:43

Don't you even know why you are asking the question?

How have you come to the conclusion that the first thread has to finish before starting the next?

---
Year happy = new Year(2007);

Sandeep_S22-Jan-07 19:53

22-Jan-07 19:53

Because I have monitored the working of the scheduler.
The thing I am unable to understand is why does it require the threads of first instance to be completed before starting the threads of the second instance (Because this is what is happening).