Problem With threads ?

[kolichina_s_s]

Hi,

I am working with around 8 threads. In each thread I am running a while loop. in thread "1" I am writing to the serial port and in thread "2" I am reading from the serial port. the problem is that writing to port is getting resolved quickly but reading from the port in the second thread is done through select() with a time out of 10 seconds. and this whole waiting is in a loop. and as long as this loop is running I am not able to switch to other threads. once this entire loop is finished then other threads get their time quantum and end them selves. Why is this so ? here is how the sample code looks for thread "2"


fcntl(fd_for_Serailport,... , FASYNC);
int x = 0;
while(x!=10) {

select(fd_for_Serailport,NULL,...,timeout); // timeout 10 secs.
if(FD_ISSET(fd_for_Serailport)) {

ReadPort();
}
else {

puts("timeout");

}

sleep(10);// even if I keep it to sleep it is not giving control other threads
x++;
}


void ReadPort()
{
just reads data from the Port and prints it.
}



Can I set the time quantum of the threads manually ? or what else i can do to avoid this problem . I am using posix threads , Please Help.

Thanks

[c_ryan]

Did you all the threads started before the loop? Even if your read thread didn't sleep in the 10 seconds, pre-emptive multithreading should give the other threads some CPU. I'd stick in plenty of console/log file output in your threads to aid debugging (assuming you haven't already done so). Why did you set FASYNC?

[vagrant]

Have you thought about using semaphores?

[kolichina_s_s]

Originally Posted by vagrant

Have you thought about using semaphores?

How can semaphore help in this . as threads are getting blocked because of a simple while loop and each of them is performing their own functions

[vagrant]

Well, I guess I'm having a little trouble understanding you.