Re: sleep() bug part 2?

Toshi,
      Looks like you are running this on a UP system.
Yes, this happens due to the nature of NGPT. NGPT thread scheduling
is done in a co-operative way and it's a non-preemptive scheduler.
On a UP, it's actually M:1 model. When one thread loops on that only one
native thread, there are no way other threads will get chance to run.
You have to use pthread_yield() to let other threads run or create more
native threads using MAXNATIVETHREADS=2.
Hope this helps.

Saurabh Desai



"Satoshi Kawase" <[email protected]>@www-124.ibm.com on 05/12/2003
04:19:19 PM

Sent by:    [email protected]


To:    "Ngpt Mailing List" <[email protected]>
cc:
Subject:    [pthreads-users] sleep() bug part 2?


hi

still trying to figure out why sleep hangs in the program I am porting.  I
wrote a simple test program to try to mimic the problems that the program I
am working on is giving me and that also gives me weird results (I assure
you it's extremely short).


#include <stdio.h>
#include <unistd.h>
#include <pthread.h>

#define SLEEP 2
#define MILLION 1000000


void *thread_func1 (void *arg){

             printf ("are we in thread 1?\n");

             while (1){
                         sleep (SLEEP);
                         printf ("1:  after %d second sleep\n", SLEEP1);
             }
}

void *thread_func2(void *arg){

             printf ("are we in thread 2?\n");
             long c = 0;

             while (1){
                         c++;
                         if (c % MILLION == 0)
                                     printf ("2:  after million
iterations\n");
             }
}

int main(){


             pthread_t our_thread1;
             pthread_t our_thread2;
             int result;


             result = pthread_create (&our_thread1, NULL, thread_func1,
NULL);
             if (result != 0)
                         printf ("thread not created successfully");


             result = pthread_create (&our_thread2, NULL, thread_func2,
NULL);
             if (result != 0)
                         printf ("thread not created successfully");



             pthread_join (our_thread1, NULL);
             pthread_join (our_thread2, NULL);

             return 0;
}

My Output looks like this:

are we in thread 1?
are we in thread 2?
2:  after million iterations
2:  after million iterations
2:  after million iterations
2:  after million iterations
2:  after million iterations
2:  after million iterations
2:  after million iterations
2:  after million iterations
2:  after million iterations
2:  after million iterations
.
.
.
.
.
.
.


And I never get anything from thread 1.  Although the program tells us we
have reached thread 1 I never get a thing from it.

I thought that this might be a thread scheduler priority issue and tried
the
command pthread_setscheduler() command to change the priority of the
threads
but GAH... It immediately seg faulted at that command.

Does anyone out there know if this is in fact a bug, or the correct nature
of NGPT, or I am doing something wrong?

Definitely losing sleep over sleep();

-Toshi
[email protected]


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