Some systems use MAP_ANON instead of MAP_ANONYMOUS.
As for communication, what sort of communication is needed? Should these processes wait for instructions, or will you need to reach out and poke them to tell them to check on something?
Last edited by Corona688; 07-29-2009 at 02:22 PM..
Reason: typo
I am running HP-UX B.11.11.
I'm increasing a parameter for a database engine so that it uses more memory to buffer the disk drive (to speed up performance). I have over 5GB of memory not being used.
But when I try to start the DB with the increased buffer parameter I get told.
"Not... (1 Reply)
Today, I wrote a test code for fork/execvp/waitpid. In the parent process, it fork 100 child processes which only execute "date" to print the current datetime. When any child process die, the parent process will receive a SIGCHLD signal. Then, the parent process will re-fork-execvp the child... (7 Replies)
hi,
this is the problem: i want to swap a linked list between 4 processes (unrelated), is there any way i can do that just by sending a pointer to a structure?
//example
typedef struct node
{
int x;
char c;
struct node *next;
} node;
or i should send the items ( x,c ) by... (9 Replies)
I need to create a shared library to access an in memory DB. The DB is not huge, but big enough to make it cumbersome to carry around in every single process using the shared library. Luckily, it is pretty static information, so I don't need to worry much about synchronizing the data between... (12 Replies)
I am writing a shared library in Linux (but compatible with other UNIXes) and I want to allow multiple instances to share a piece of memory -- 1 byte is enough. What's the "best" way to do this? I want to optimize for speed and portability.
Obviously, I'll have to worry about mutual exclusion. (0 Replies)
hi, i want to write a code for forking 3 4 child. n wants that every child process one of the account from global account list. i wrote a program for that, but problem is every child is processing every account in list. what can me done to avoid it.
attaching code with it
#include <stdio.h>... (2 Replies)
Hi gurus, I would like to fork more children and then write their return values: so far I tried:
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
int main(void)
{
pid_t pid;
int rv=0, i;
... (5 Replies)
hello everyone,
i am making a tcp chat server using c in linux. i have used socket programming to connect the server and the client.
can anyone please let me know how i can use forking for multiple clients??
thank you (1 Reply)
Hello.
I am new to this forum and I would like to ask for advice about low level POSIX programming.
I have to implement a POSIX compliant C shared library.
A file will have some variables and the shared library will have some functions which need those variables.
There is one special... (5 Replies)
Discussion started by: iamjag
5 Replies
LEARN ABOUT NETBSD
vfork
VFORK(2) BSD System Calls Manual VFORK(2)NAME
vfork -- spawn new process in a virtual memory efficient way
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <unistd.h>
pid_t
vfork(void);
DESCRIPTION
The vfork system call creates a new process that does not have a new virtual address space, but rather shares address space with the parent,
thus avoiding potentially expensive copy-on-write operations normally associated with creating a new process. It is useful when the purpose
of fork(2) would have been to create a new system context for an execve(2). The vfork system call differs from fork(2) in that the child
borrows the parent's memory and thread of control until a call to execve(2) or an exit (either by a call to _exit(2) or abnormally). The
parent process is suspended while the child is using its resources.
The vfork system call returns 0 in the child's context and (later) the pid of the child in the parent's context.
The vfork system call can normally be used just like fork(2). It does not work, however, to return while running in the childs context from
the procedure that called vfork() since the eventual return from vfork() would then return to a no longer existent stack frame. Be careful,
also, to call _exit(2) rather than exit(3) if you can't execve(2), since exit(3) will flush and close standard I/O channels, and thereby mess
up the standard I/O data structures in the parent process. (Even with fork(2) it is wrong to call exit(3) since buffered data would then be
flushed twice.)
RETURN VALUES
Same as for fork(2).
ERRORS
Same as for fork(2).
SEE ALSO execve(2), fork(2), sigaction(2), wait(2)HISTORY
The vfork() function call appeared in 3.0BSD. In 4.4BSD, the semantics were changed to only suspend the parent. The original semantics were
reintroduced in NetBSD 1.4.
BUGS
Users should not depend on the memory sharing semantics of vfork() as other ways of speeding up the fork process may be developed in the
future.
To avoid a possible deadlock situation, processes that are children in the middle of a vfork() are never sent SIGTTOU or SIGTTIN signals;
rather, output or ioctl(2) calls are allowed and input attempts result in an end-of-file indication.
BSD January 3, 1998 BSD