Programming Forums > Application Development > C++

Lesliect6 · Jun 29th, 2007, 7:22 AM

Quote:

Unless your app is multi-threaded of course, because Sleep only 'sleeps' one thread so if a second thread is still working away then the cpu is still in use.

Whoops...you're right...where do you change that in project properties?

Thanks,

Leslie

grumpy · Jun 29th, 2007, 9:02 AM

Quote:

Originally Posted by Lesliect6

Whoops...you're right...where do you change that in project properties?

If there is a project property related to developing a multithreaded application, the option you change is specific to your development environment ..... and usually only links in a library that is thread safe.

Making an application multi-threaded is more than just setting a few project options. It is also necessary to break up your code so parts can be executed on different threads, create the threads, define mechanisms to synchronise sharing of data between threads, (optionally) move threads to particular processors, handle the results when a thread terminates, etc etc.

Eoin · Jun 29th, 2007, 9:04 AM

Threading isn't something you can turn on and off like that. I suspect the setting you're thinking of is for linking against thread safe runtime or not. At least that would be the case for native applications, but I'm not familiar enough with .NET to know if those settings still apply.

It is reasonably safe to assume that if you are not actively using multiple threads yourself then that is not the issues so that bring us back to what has already been said-

If the "quite long and complicated code" takes longer than X seconds to run then there is nothing you can do, if it doesn't then Sleep() will work if it's used correctly.

Edit - Replied same time as Grumpy so repeated some of what he said.

Lesliect6 · Jun 30th, 2007, 7:21 AM

OK, this is getting weird. The Sleep() function does work, but only in the followng case :

(Toggle Plain Text)

#include ...

using ...

int main(array<System::String ^> ^args)
{
     Sleep(5000);

     for(...)
    {
    ...***THE CODE***
    }
}

but not in this case :

(Toggle Plain Text)

#include ...

using ...

int main(array<System::String ^> ^args)
{
     for(...)
    {
    Sleep(5000);
    ...***THE CODE***
    }
}

In the first case, it does sleep 5 seconds at 0 percent CPU power, whereas in the second it is constantly at 50 percent. What can the problem be?

Thank you,

Leslie

Eoin · Jun 30th, 2007, 8:54 AM

Yep that is odd. In the second case it must surely at least sleep for an initial 5 seconds. If after that it never seem to sleep again it has to be that ***THE CODE*** never actually stops working so hence there isn't ever a second iteration of the for loop.

Lesliect6 · Jun 30th, 2007, 10:13 AM

The ***CODE*** gives accurate and good results, meaning that it does iterate the number of times defined. However, as you said, it doesn't sleep, even for the first time.

Eoin · Jul 1st, 2007, 1:17 PM

To be honest I'm a bit stumped. And I really just don't know enough about .NET to offer alternatives but if you read this msdn link on timers I'm sure you'll be able to figure something to, there's lots of sample code.

Dameon · Jul 1st, 2007, 2:25 PM

The example that you posted should not stay at half utilization. It should drop to zero for five seconds at a time with spikes during ***THE CODE***. Have you set breakpoints or added debugging output in useful places to tell what's actually happening?

Jun 29th, 2007, 9:04 AM	#13
Eoin Hobbyist Programmer Join Date: Jun 2006 Location: Ireland Posts: 152 Rep Power: 3	Threading isn't something you can turn on and off like that. I suspect the setting you're thinking of is for linking against thread safe runtime or not. At least that would be the case for native applications, but I'm not familiar enough with .NET to know if those settings still apply. It is reasonably safe to assume that if you are not actively using multiple threads yourself then that is not the issues so that bring us back to what has already been said- If the "quite long and complicated code" takes longer than X seconds to run then there is nothing you can do, if it doesn't then Sleep() will work if it's used correctly. Edit - Replied same time as Grumpy so repeated some of what he said. __________________ Visit my website BinaryNotions.

Jun 30th, 2007, 7:21 AM	#14
Lesliect6 Programmer Join Date: Aug 2005 Posts: 68 Rep Power: 4	OK, this is getting weird. The Sleep() function does work, but only in the followng case : (Toggle Plain Text) #include ... using ... int main(array<System::String ^> ^args) { Sleep(5000); for(...) { ...*THE CODE* } } #include ... using ... int main(array<System::String ^> ^args) { Sleep(5000); for(...) { ...*THE CODE* } } but not in this case : (Toggle Plain Text) #include ... using ... int main(array<System::String ^> ^args) { for(...) { Sleep(5000); ...*THE CODE* } } #include ... using ... int main(array<System::String ^> ^args) { for(...) { Sleep(5000); ...*THE CODE* } } In the first case, it does sleep 5 seconds at 0 percent CPU power, whereas in the second it is constantly at 50 percent. What can the problem be? Thank you, Leslie

Jun 30th, 2007, 8:54 AM	#15
Eoin Hobbyist Programmer Join Date: Jun 2006 Location: Ireland Posts: 152 Rep Power: 3	Yep that is odd. In the second case it must surely at least sleep for an initial 5 seconds. If after that it never seem to sleep again it has to be that *THE CODE* never actually stops working so hence there isn't ever a second iteration of the for loop. __________________ Visit my website BinaryNotions.

Jul 1st, 2007, 1:17 PM	#17
Eoin Hobbyist Programmer Join Date: Jun 2006 Location: Ireland Posts: 152 Rep Power: 3	To be honest I'm a bit stumped. And I really just don't know enough about .NET to offer alternatives but if you read this msdn link on timers I'm sure you'll be able to figure something to, there's lots of sample code. __________________ Visit my website BinaryNotions.

Jul 1st, 2007, 2:25 PM	#18
Dameon Troll Join Date: Apr 2005 Location: Texas Posts: 732 Rep Power: 4	The example that you posted should not stay at half utilization. It should drop to zero for five seconds at a time with spikes during *THE CODE*. Have you set breakpoints or added debugging output in useful places to tell what's actually happening? __________________ MD5(sig) = bcef75433db02e9ad9bf81d6f7c5c270

Jun 30th, 2007, 10:13 AM	#16
Lesliect6 Programmer Join Date: Aug 2005 Posts: 68 Rep Power: 4	The *CODE* gives accurate and good results, meaning that it does iterate the number of times defined. However, as you said, it doesn't sleep, even for the first time.

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Programming Forums > Application Development > C++

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