将forks转换为pthread

Question

有没有什么办法可以将这段代码转换为使用Posix (p)线程而不是fork？我必须对两者在内存和处理能力方面的差异进行实验。我正在测试不同数量的进程对处理器CPU%的影响，这取决于内核的数量。

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

#define N 16 /* define the total number of processes we want */ 

float total=0; 

int compute() 
{ 
 int i; 
 float oldtotal=0, result=0; 

 the arbitrary number 1000 */ 

 for(i=0;i<2000000000;i++) 
 { 
 result=sqrt(1000.0)*sqrt(1000.0); 
 }  
 /* Print the result \u2013 should be no surprise */ 
 printf("Result is %f\n",result); 

 oldtotal = total; 
 total = oldtotal + result; 

 /* Print running total so far. */ 
 printf("Total is %f\n",total); 

 return(0); 
} 


int main() 
{ 
 int pid[N], i, j; 
 float result=0; 

 printf("\n");  


 for(i=0;i<N;i++) 
 { 
 if((pid[i]=fork())==-1) 
 { 
 exit(1); 
 } 
 else if(pid[i] > 0) 
 { 
 /* give a message about the proc ID */ 
 printf("Process Id for process %d is %d\n",i,getpid()); 

 /* call the function to do some computation. */ 
 compute(); 

 break; 
 } 
 } 
 return 0; 
} 

Answer 1

像这样的东西

#include <pthread.h>

void *cback(void *void_ptr) 
{

 int i;   
 float oldtotal=0, result=0; 


 for(i=0;i<2000000000;i++)   
 { 
     result=sqrt(1000.0)*sqrt(1000.0);  
 }   
 printf("Result is %f\n",result); 

 oldtotal = total;   total = oldtotal + result; 

 printf("x increment finished\n");

 return NULL;

}

int main () 
{  
pthread_t onethread;

if (pthread_create(&onethread, NULL, cback, NULL) != 0)
{
   printf("error creating thread\n");
}

}

请参阅man page和tutorial