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Full Discussion: fork-getrusage
Top Forums Programming fork-getrusage Post 302291669 by nicos on Thursday 26th of February 2009 05:27:29 AM
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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setpgid(2)							   System Calls 							setpgid(2)

NAME
setpgid - set process group ID SYNOPSIS
#include <sys/types.h> #include <unistd.h> int setpgid(pid_t pid, pid_t pgid); DESCRIPTION
The setpgid() function sets the process group ID of the process with ID pid to pgid. If pgid is equal to pid, the process becomes a process group leader. See intro(2) for more information on session leaders and process group leaders. If pgid is not equal to pid, the process becomes a member of an existing process group. If pid is equal to 0, the process ID of the calling process is used. If pgid is equal to 0, the process specified by pid becomes a process group leader. RETURN VALUES
Upon successful completion, 0 is returned. Otherwise, -1 is returned and errno is set to indicate the error. ERRORS
The setpgid() function will fail if: EACCES The pid argument matches the process ID of a child process of the calling process and the child process has successfully executed one of the exec family of functions (see exec(2)). EINVAL The pgid argument is less than (pid_t) 0 or greater than or equal to PID_MAX, or the calling process has a controlling ter- minal that does not support job control. EPERM The process indicated by the pid argument is a session leader. EPERM The pid argument matches the process ID of a child process of the calling process and the child process is not in the same session as the calling process. EPERM The pgid argument does not match the process ID of the process indicated by the pid argument, and there is no process with a process group ID that matches pgid in the same session as the calling process. ESRCH The pid argument does not match the process ID of the calling process or of a child process of the calling process. 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), exit(2), fork(2), getpid(2), getsid(2), attributes(5), standards(5) SunOS 5.10 28 Dec 1996 setpgid(2)
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