Forcing context switching between Labview threads

Hello,
I have 2 threads interfacing with 2 serial ports on Labview ( Lets say Thread1 , is responsible for polling COM1 and Thread2 for polling COM2 ).
By using occurrences, Thread1 executes before Thread2 and context switching is done according to Labview between the threads. Now, I'm looking to do the following :
As soon as a specific block of code is executed in Thread1, I need Labview to force context switching to execute Thread2. I want to do this in order to synchronize the data received from the 2 threads.
1- So, can this be done, or are there other ways for synchronization ?
2- What if I want Labview to run as a real-time process or a higher priority thread on Windows XP in order to emulate the real-time effect on a Windows XP and not get any delays ? ( I already changed the process priority from the Process explorer, but there seems no effect. I also changed the Labview threads priority to real-time)
3- Are there better approached for (1) & (2) ?
Thank you,
Walid F. Abdelfatah

wfarid wrote:
I already used occurrences for Thread1 to execute before Thread2. Does occurrences guarantee that Labview will switch the context to Thread2, as soon as the context is fired ?
-- Walid
NO!
LV depends on the OS to schedule threads. If you are sticking with Non-RT then you would be better off getting thread one to do the work while it has teh CPU.
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

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Hello !
The following program is for 3 Threads which do
context switching.
Often we get '0' zero for the low priority thread when
we run this program.
MY QUESTION IS WHY DO WE GET ZERO ?Presumably because the low priority thread gets no CPU time.
>
As far as my understanding is concerned; even if
preemptive multitasking is done by the threads,
the low priority thread should have run through few
iterations and thus giving some value other
than zero '0'.You can't make ANY assumptions about when or how much CPU time a given thread will get. Why don't you let your main thread sleep longer--a minute or 5 or ten--and see if LO gets some cycles then.
Secondly most of the time we get negative values for
the high priority thread. Why is that ?count = Integer.MAX_VALUE;
count++; // --> Integer.MIN_VALUE (-2^31)
I guess 10 seconds is enough time for a thread in a tight loop to count to 2 billion.
Is it because of the fact that volatile sets the
variable 'running' to some different value ?Volatile does nothing of the sort, and, in any case, isn't even in your code.
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Error Labview 10.JPG ‏19 KB

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Hi,
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Software developer
www.mcm-electronics.com
PS: Don't forget to rate a good anwser ; )
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PORTUGAL
Attachments:
Prototype_Plot_Switch1 changedvi.vi ‏24 KB

Forcing context switching between Labview threads

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