How to run a function in background in c

nathan · 08-26-2009, 02:38 AM

Hi All,

I want to run a function in background and continue with executing next statements,

eg:

main()
{

..
....
func(); // want to run in back ground and it is a while(1). executing
// in infinite loop
funct2(); // this should execute normally
..
...

}

kindly suggest me

Thanks in advance
nathan

Nylex · 08-26-2009, 02:40 AM

I could be wrong, but I think you'd have to look into multi-threading for this.

i92guboj · 08-26-2009, 02:45 AM

Yep, look intro threading.

nathan · 08-26-2009, 02:49 AM

Quote:

Originally Posted by Nylex

I could be wrong, but I think you'd have to look into multi-threading for this.

Thanks for your reply,

if i implement it as thread it will be running always..
but i need a provision to stop this func and start again (like this i may doing many times in my application) .

kindly suggest me how to stop a running thread and restart it again
(syntax)

or
any other methods also ..if any

thanks in advance
nathan

Nylex · 08-26-2009, 02:52 AM

Unfortunately, I can't help you with threading in C as I've never done it (I've only done threading in Java and naturally there's a different API to be used).

i92guboj · 08-26-2009, 03:08 AM

Quote:

Originally Posted by nathan

Thanks for your reply,

if i implement it as thread it will be running always..
but i need a provision to stop this func and start again (like this i may doing many times in my application) .

Threads can be destroyed, created or whatever at a given momment. You could very well fork a new process, but that usually is unnecessary, wastes resources and makes things more difficult.

You should read something about pthreads. Threads can't be explained in a post. For example:

https://computing.llnl.gov/tutorials/pthreads/

Tinkster · 08-26-2009, 04:38 AM

Moved: This thread is more suitable in <Programming> and has been moved accordingly to help your thread/question get the exposure it deserves.

wje_lq · 08-26-2009, 06:40 AM

If you want to be able to stop the background function asynchronously, don't use POSIX threads. POSIX threads don't handle asynchronous interruption well. Instead, use fork(), kill(), and waitpid().

One complication that might arise if you follow my advice is that you'll have to take additional steps if you want the child process and the parent process to share memory (for variables, for example).

Hope this helps.

nathan · 08-26-2009, 07:37 AM

Quote:

Originally Posted by i92guboj

Threads can be destroyed, created or whatever at a given momment. You could very well fork a new process, but that usually is unnecessary, wastes resources and makes things more difficult.

You should read something about pthreads. Threads can't be explained in a post. For example:

https://computing.llnl.gov/tutorials/pthreads/

Hi,

Thanks a lot for your info

kindly go through it

void * func1( void)
{

..
...
}

main()
{
int ret;
pthread_t test1;

ret = pthread_create(&test1,NULL,&func1,NULL);
if(ret == 0)
{
printf("\n successin opening thread \n");
}

pthread_exit(test1); // is it correct way of closing a thread and here i getting following warning:
// warning: passing arg 1 of `pthread_exit' makes pointer from integer without a cast

}

kindly suggest me the correct one.

thanks
Nathan

jiml8 · 08-26-2009, 04:40 PM

To synchronize the threads you need to use mutual exclusion locks and semaphores (mutexes). A complete discussion of pthreads will also include a discussion of mutexes.

nathan · 08-28-2009, 02:14 AM

Quote:

Originally Posted by jiml8

To synchronize the threads you need to use mutual exclusion locks and semaphores (mutexes). A complete discussion of pthreads will also include a discussion of mutexes.

Hi All,

finally i implemented it as timer calling the function at a particular interval of time.

Any difference in performance with timer and thread ?

Your comments, suggestions are most welcome

Thnaks in advance
Nathan

jiml8 · 08-28-2009, 12:01 PM

A timer is fine...for things that should be timed.

If you are depending on a timer to synchronize different execution streams, you probably will get bitten sooner or later - and, more than likely, intermittently.