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I have a problem with thread priorities, the scenario is shown as the following.
A thread of "Normal" priority(Thread-A) is running, and do AutoResetEvent.WaitOne() after it has started another thread of "Highest" priority (Thread-B). Thread-B will do AutoResetEvent.Set() in the middle of it process.
As I have imagined, Thread-A will not move on until Thread-B has finished completely.
But to my surprise, the Thread-A may soon move on if Thread-B does Set().
Why the thread with the highest priority won't finish before threads of low priority move on.
Thank you.
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Thread priority gives you absolutely no control in which order threads are executed. It's just an indicator that if the processor is fully used that one thread gets more of it than another thread. It might even occur that a low priority thread can finish before a high priority thread just because it makes less calculations. So in your example it's correct behaviour that both threads run parallel - only that Thread-B gets a bit more cpu power. I would even go so far that on dual core processors (assuming no other threads/processes are running beside these two) that the priority would not have any effect at all.
If you want Thread-A to run after Thread-B has finished then Thread-B should call Set() at its very end and not somewhere in the middle.
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Robert Rohde wrote: If you want Thread-A to run after Thread-B has finished then Thread-B should call Set() at its very end and not somewhere in the middle.
I imagined that Windows will work in someway like the behavior of some embedded OS.
Well, it seems that I am wrong.
I will reconsider the constructure of program.
Thank you very much.
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Well it is exactly the same behaviour as the process priority you can set via task manager. If you have a long cpu consuming process (like packing your C harddrive  ) which you set to high you can still fire up Calc, calculate something and shut it down - all while a higher priority process is running paralell. Surely it will behave very slow but it still works.
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I see.
Is there anything I should be careful with about the number of threads in a single process?You see, my process doesn't use ThreadPool. Instead, all the threads are invoked just by Thread.Start().
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Even if priority defined the sequence of execution, you still are not guaranteed that the high-priority thread would come to completion after ending the process in the lower priority thread. The reason is that each thread is given a set amount of time to execute. Once that time expires the kernel moves onto the next thread, and so on. Priority defines how long a task will sit in the queue before it gets to run once again. That is why setting a thread to too high of a priority is dangerous. If you have a very tight loop in a thread running at the same level as the OS, you would remain up in the high-eschelon and run more than that OS would.
This gets even hairier if you are doing an interupt specific task (printing, IO, tcpip calls, etc.) since each time you do an interrupt, you get into an even different queue and have to wait for other tasks to complete as well as your interrupt driven task before you get to execute once again.
I suggest doing searches on OS Queue Theory to get a better understanding of queue management. This is OS 101 and operates like this, at a basic level, in any multi-threaded environment. There are entire schools of thread management to determine the most efficient queue management algorithms to make every task run transparent to the thread management while maintaining excellant performance on high priority threads.
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Your reply is very helpful.
Thank you 
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You're welcome. IBM's Big Blue was the 'research project' for the queue technology in MVS. You may find researching the chess algorithms for finding the next move. This is the similar approach for determine 'which is the next thread' when processing multi-thread environment.
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Hello,
I want to print directly to parallel port for fast writing (of-course when i use DMPs). I did following code but it generates an exception telling that it can't handle any device:
TextWriter sw = new StreamWriter("LPT1");<br />
sw.WriteLine("This is a test print!"); <br />
sw.Close();
Currently I have working version of it(VB6)
Open "LPT1" For Output As #1<br />
Print #1, "Bla,bla,bla...."<br />
Close #1
and C++
FILE *ptr = fopen("LPT1","w");<br />
fprintf(ptr,"Bla,bla,bla......");<br />
fclose(ptr);
How can I do that? Thanks in advance.
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I’ve finally understand the benefit with using events. I’ve made some my own but have a problem when not subscribing on an event.
public event EventHandler UpdateListCountChangedEvent;<br />
UpdateListCountChangedEvent(this, new EventArgs());
I got an exception (Object reference not set to an instance of an object) in those cases the function UpdateListCountChangedEvent(…) is called and I have no one that listen to it…
_____________________________
...and justice for all
APe
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You must first check if there are any subscribers to the event bvefore raising it...this is usually done with a particular pattern of event/protected method.
public class MyClassWithEvent
{
public event EventHandler MyEvent
protected virtual void OnMyEvent(EventArgs e)
{
if(MyEvent != null)
{
MyEvent(this,e);
}
}
}
The reason its done like this is 2-fold.
1) It enables methods in your class to easily raise the event without worrying if there are any subscribers... so you could have a method in there like:
public void DoSomethingAndRaiseMyEvent()
{
this.OnMyEvent(EventArgs.Empty);
}
2) It enables derived classes to change the behaviour slightly by overriding OnMyEvent.
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Perfect! Thanks!
_____________________________
...and justice for all
APe
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send me the code for creating dynamic checkboxes in html using _javascript
-- modified at 3:18 Tuesday 18th April, 2006
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<script language="JavaScript" type="text/javascript">
document.write("<input type=checkbox>");
</script>
Enjoy !
Best regards, Alexey.
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umaheshchandra wrote: send me the code
Try being polite and asking, rather than demanding.
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How could i add a custom icon to a windows form?
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look for icon property in your form's property window (generally located in right hand side pane of your IDE).
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I have used the icon property before.But the custom icon never appear.i dont know why?
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Hi ,
I have to fill a datatable with data from an ADODB recordset. I am using OleDBDataAdapter's fill method to do so.
The problem is as follows -
There is an adDateTime field in the recordset. Upon calling the fill method, it is converted to System.DateTime. But the 'time' part is lost and i get only date values for all the rows.
Could anybody please help ?
Thanks & Regards, Maau
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This is my code:
Excel.Range _Rng = (Excel.Range)_xlsSheet.get_Range("A1:H17", Missing.Value);
Where “C5:F11” is a merged cells in range “A1:H17”
It always report errors : Can't get object.
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hi, in dll project i create document,but if i add it to the other
project , i can not see my dll documents. why?
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You must provide access to your document.
What is the type of your document ?
Best regards, Alexey.
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hi guys!
need some help from u guys...
i hve just started working on c# from vb.net
and i m facing some problems..
in vb.net we can withevents keyword and call all the events of controls like for eg. for textbox textbox_textchanged(), textbox_keydown(),textbox_lostFocus(), etc .
but in c# i didnt found such keyword or related stuff..
coz of which i m not able to use such events properly can anyone let me know how to use these events..
thanks..
abhinav
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Nope. That's the ONLY cool thing about VB. In C#, you need to go to your load event ( or the events list in the properties, then it goes in initializeComponent automagically ) and set the event handlers.
Christian Graus - Microsoft MVP - C++
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In order to make use of those events,U need to use Javascript onkeydown,focus events
"Aim to go where U have never been B4 and Strive to achieve it"
http://groups.yahoo.com/subscribe/dotnetforfreshers
http://himabinduvejella.blogspot.com
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