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Full Discussion: fork vs pthread_create
Top Forums Programming fork vs pthread_create Post 302655895 by rupeshkp728 on Thursday 14th of June 2012 02:55:32 AM
Old 06-14-2012
fork vs pthread_create

Suppose I have a simple program main() with a global varibale int x=0.
Code:
int x = 0;
main()
{
print("%d\n",x);

}

I want to create two threads/process which must access this variable x in sync.
Which one will be better threads( pthread_create ) or process( fork )?

If I go with fork() then will I be able to use the IPC mechanism like semaphore/mutex,conditional variables etc. between the process as I understand that separate variable x will be created for both the process?

Last edited by Scrutinizer; 06-14-2012 at 04:09 AM.. Reason: code tags
 

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SEM_INIT(3)						     Linux Programmer's Manual						       SEM_INIT(3)

NAME
sem_init - initialize an unnamed semaphore SYNOPSIS
#include <semaphore.h> int sem_init(sem_t *sem, int pshared, unsigned int value); Link with -pthread. DESCRIPTION
sem_init() initializes the unnamed semaphore at the address pointed to by sem. The value argument specifies the initial value for the sem- aphore. The pshared argument indicates whether this semaphore is to be shared between the threads of a process, or between processes. If pshared has the value 0, then the semaphore is shared between the threads of a process, and should be located at some address that is visible to all threads (e.g., a global variable, or a variable allocated dynamically on the heap). If pshared is nonzero, then the semaphore is shared between processes, and should be located in a region of shared memory (see shm_open(3), mmap(2), and shmget(2)). (Since a child created by fork(2) inherits its parent's memory mappings, it can also access the semaphore.) Any process that can access the shared memory region can operate on the semaphore using sem_post(3), sem_wait(3), etc. Initializing a semaphore that has already been initialized results in undefined behavior. RETURN VALUE
sem_init() returns 0 on success; on error, -1 is returned, and errno is set to indicate the error. ERRORS
EINVAL value exceeds SEM_VALUE_MAX. ENOSYS pshared is nonzero, but the system does not support process-shared semaphores (see sem_overview(7)). CONFORMING TO
POSIX.1-2001. NOTES
Bizarrely, POSIX.1-2001 does not specify the value that should be returned by a successful call to sem_init(). POSIX.1-2008 rectifies this, specifying the zero return on success. SEE ALSO
sem_destroy(3), sem_post(3), sem_wait(3), sem_overview(7) COLOPHON
This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. Linux 2012-05-13 SEM_INIT(3)
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