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fork-getrusage

 
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Old 02-26-2009
fork-getrusage
Hello everybody!
I wrote the following code:
...
int main()
{
pid_t pid;
for (int i=0;i<100;i++)
{
pid=fork();
if(pid==0)
{execl("md5sum","myprog",NULL);exit(1)}
else if(pid>0)
{ waitpid(pid,&status,0);getrusage(RUSAGE_CHILDREN,&usage);}

The above program creates 100 processes concurrently! I want to fork one process after another(is finished). What I want to do is, get the utime of child process each time. However, i find out that stime of one process is influenced by the utime of previous process!
Output example:
pid utime
8359 0.172010
8360 0.176011
8406 0.176011
8407 0.176011
8408 0.176011
8409 0.184011
8410 0.184011
Why this happens?

Thanx in advance
 
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LEARN ABOUT SUNOS

getpgrp

getpid(2)							   System Calls 							 getpid(2)

NAME

       getpid, getpgrp, getppid, getpgid - get process, process group, and parent process IDs

SYNOPSIS

       #include <unistd.h>

       pid_t getpid(void);

       pid_t getpgrp(void);

       pid_t getppid(void);

       pid_t getpgid(pid_t pid);

DESCRIPTION

       The getpid() function returns the process ID of the calling process.

       The getpgrp() function returns the process group ID of the calling process.

       The getppid() function returns the parent process ID of the calling process.

       The getpgid() function returns the process group ID of the process whose process ID is equal to pid, or the process group ID of the calling
       process, if pid is equal to 0.

RETURN VALUES

       Upon successful completion, these functions return the process group ID. Otherwise, getpgid() returns (pid_t)-1 and sets errno to  indicate
       the error.

ERRORS

       The getpgid() function will fail if:

       EPERM	       The  process  whose  process   ID is equal to pid is not in the same session as the calling process, and the implementation
		       does not allow access to the process group ID of that process from the calling process.

       ESRCH	       There is no process with a process ID equal to pid.

       The getpgid() function may fail if:

       EINVAL	       The value of the pid argument is invalid.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Async-Signal-Safe 	   |
       +-----------------------------+-----------------------------+

SEE ALSO

       intro(2), exec(2), fork(2), getsid(2), setpgid(2), setpgrp(2), setsid(2), signal(3C), attributes(5), standards(5)

SunOS 5.10							    28 Dec 1996 							 getpid(2)