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Problem due to Fork Error
Post 302214277 by matrixmadhan on Sunday 13th of July 2008 03:15:38 AM
07-13-2008
Please do read the rules of the forum and donot bump up with questions if they are not promptly answered. 
Coming to the point,
monitor program would be a parent process which would fork() to create new child process, better to have some kind of count to control the child process creation ( MAX_CHILD_PROCESS_ALLOWED ), once fork is successful parent gets the child pid, store them in an array or any other data structure, check for the existence of the child by sending kill -0 ( to see if they exist ), or register any signal handlers in the child if any communication needs to be carried over between parent and child.
This is just a pointer and you will have many interesting challenges like daemon -izing, defunct process creation etc.
Give it a shot, post us if you are stuck up somewhere.
Coming to the point,
monitor program would be a parent process which would fork() to create new child process, better to have some kind of count to control the child process creation ( MAX_CHILD_PROCESS_ALLOWED ), once fork is successful parent gets the child pid, store them in an array or any other data structure, check for the existence of the child by sending kill -0 ( to see if they exist ), or register any signal handlers in the child if any communication needs to be carried over between parent and child.
This is just a pointer and you will have many interesting challenges like daemon -izing, defunct process creation etc.
Give it a shot, post us if you are stuck up somewhere.
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LEARN ABOUT OPENDARWIN
fork
FORK(2) BSD System Calls Manual FORK(2) NAME
fork -- create a new process SYNOPSIS
#include <sys/types.h> #include <unistd.h> pid_t fork(void); DESCRIPTION
Fork() causes creation of a new process. The new process (child process) is an exact copy of the calling process (parent process) except for the following: o The child process has a unique process ID. o The child process has a different parent process ID (i.e., the process ID of the parent process). o The child process has its own copy of the parent's descriptors. These descriptors reference the same underlying objects, so that, for instance, file pointers in file objects are shared between the child and the parent, so that an lseek(2) on a descriptor in the child process can affect a subsequent read or write by the parent. This descriptor copying is also used by the shell to establish standard input and output for newly created processes as well as to set up pipes. o The child processes resource utilizations are set to 0; see setrlimit(2). RETURN VALUES
Upon successful completion, fork() returns a value of 0 to the child process and returns the process ID of the child process to the parent process. Otherwise, a value of -1 is returned to the parent process, no child process is created, and the global variable errno is set to indicate the error. ERRORS
Fork() will fail and no child process will be created if: [EAGAIN] The system-imposed limit on the total number of processes under execution would be exceeded. This limit is configuration- dependent. [EAGAIN] The system-imposed limit MAXUPRC (<sys/param.h>) on the total number of processes under execution by a single user would be exceeded. [ENOMEM] There is insufficient swap space for the new process. SEE ALSO
execve(2), wait(2) HISTORY
A fork() function call appeared in Version 6 AT&T UNIX. 4th Berkeley Distribution June 4, 1993 4th Berkeley Distribution