Behavior of pthreads Post: 302071344

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Top Forums Programming Behavior of pthreads Post 302071344 by nhrraj on Saturday 15th of April 2006 12:09:00 PM

04-15-2006

Registered User

Behavior of pthreads

Hi All,
I ve written a small program to get started off with pthreads. I somehow feel the program doesnt meet the purpose. Please find the code and the output below. Please find my question at the bottom.

Code:

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

void *PrintThread1(void *threadid)
{
  int i;
  for (i=0;i<50;i++)
  {
    printf("\n%d: Thread1!\n", threadid);
  }
}
void *PrintThread2(void *threadid)
{
    int i;
    for (i=0;i<50;i++)
    printf("\n%d: Thread2!\n", threadid);
    pthread_exit(NULL);
}

int main(int argc, char *argv[])
{
  pthread_t threads, threads1;
  int rc, t1=0, t2=1;

  printf("Creating thread %d\n", t1);
  rc = pthread_create(&threads, NULL, PrintThread1, (void *)t1);
    if (rc)
    {
      printf("ERROR; return code from pthread_create() is %d\n", rc);
    exit(-1);
    }
  printf("Creating thread %d\n", t2);
  rc = pthread_create(&threads1, NULL, PrintThread2, (void *)t2);
    if (rc)
    {
      printf("ERROR; return code from pthread_create() is %d\n", rc);
    exit(-1);
    }

  pthread_exit(NULL);
}

Output
--------
0: Thread1! (printed when i=0)

0: Thread1!

...............

...............

0: Thread1! (printed when i=49)

1: Thread2! (printed when i=0)

1: Thread2!

-----------

-----------

1: Thread2! (printed when i=49)

My question is:
If both the threads are running the output from the functions printThread1 and PrintThread2 should be mingled?
i am in HP-UX 10.20
Same program in cygwin environment yields mingled output.
Please help me with this...

raj

nhrraj

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LEARN ABOUT REDHAT

assert_perror

ASSERT_PERROR(3)					     Linux Programmer's Manual						  ASSERT_PERROR(3)

NAME

       assert_perror - test errnum and abort

SYNOPSIS

       #include <assert.h>

       void assert_perror(int errnum);

DESCRIPTION

       If  the	macro  NDEBUG  was defined at the moment <assert.h> was last included, the macro assert_perror() generates no code, and hence does
       nothing at all.	Otherwise, the macro assert_perror() prints an error message to standard output and  terminates  the  program  by  calling
       abort()	if  errnum  is nonzero. The message contains the filename, function name and line number of the macro call, and the output of str-
       error(errnum).

RETURN VALUE

       No value is returned.

CONFORMING TO

       This is a GNU extension.

BUGS

       The purpose of the assert macros is to help the programmer find bugs in his program, things that cannot happen unless there  was  a  coding
       mistake.   However,  with  system  or  library  calls the situation is rather different, and error returns can happen, and will happen, and
       should be tested for.  Not by an assert, where the test goes away when NDEBUG is defined, but by proper error handling code. Never use this
       macro.

SEE ALSO

       exit(3), abort(3), assert(3), strerror(3)

GNU
								    2002-08-25							  ASSERT_PERROR(3)

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