Lightweight Processes on SunOS4.0

[Ari Gross]

There seems to be a problem with the printf command when using the
lightweight process library.  Here is an example taken from the SUN
tutorial document on lightweight processes (Ch 6, pgs 75-76) that is
supposed to give an example of how threads can be used to run coroutines.
If the string constants in the example are replaced with integer
variables, the code compiles and runs properly, as in the tutorial
example. If the constants are changed to floats however, as below, the
program hangs.  It looks like there is a problem with the print command
when used with threads. Any suggestions ???  [BTW, I am running this on a
SUN 3.]

Ari Gross
ari at cs.columbia.edu

/* buggy coroutine code using threads */

#include <lwp/lwp.h>
#include <lwp/stackdep.h>

thread_t  co1;
thread_t  co2;
thread_t  co3;

main()
{
     float  num1;
     int  coroutine(), other();
     lwp_self(&co1);

     lwp_setstkcache(1000,3);
     lwp_create(&co2, coroutine, MINPRIO, 0, lwp_newstk(), 0);
     lwp_create(&co3, other, MINPRIO, 0, lwp_newstk(), 0);

     num1 = 1.0;
     printf("%f\n",num1);
     lwp_yield(THREADNULL);
     num1 = 4.0;
     printf("%f\n",num1);
     lwp_yield(co3);
     num1 = 6.0;
     printf("%f\n",num1);
     exit(0);
   }

coroutine() {

     float  num2;

     num2 = 2.0;
     printf("%f\n",num2);

       if (lwp_yield(THREADNULL) < 0) {
	      lwp_perror("bad yield");
              return;
	    }

     num2 = 7.0;
     printf("%f\n",num2);

   }

other()  {

       float  num3;

       num3 = 3.0;
       printf("%f\n",num3);
       lwp_yield(THREADNULL);

       num3 = 5.0;
       printf("%f\n",num3);
   }

/* end  code */