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POvfork never ends
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copied!<p>The following code never ends. Why is that? </p> <pre><code>#include <sys/types.h> #include <stdio.h> #include <unistd.h> #define SIZE 5 int nums[SIZE] = {0, 1, 2, 3, 4}; int main() { int i; pid_t pid; pid = vfork(); if(pid == 0){ /* Child process */ for(i = 0; i < SIZE; i++){ nums[i] *= -i; printf(”CHILD: %d “, nums[i]); /* LINE X */ } } else if (pid > 0){ /* Parent process */ wait(NULL); for(i = 0; i < SIZE; i++) printf(”PARENT: %d “, nums[i]); /* LINE Y */ } return 0; } </code></pre> <p><strong>Update:</strong></p> <p>This code is just to illustrate some of the confusions I have regarding to <code>vfork()</code>. It seems like when I use <code>vfork()</code>, the child process doesn't copy the address space of the parent. Instead, it shares the address space. In that case, I would expect the nums array get updated by both of the processes, my question is in what order? How the OS synchronizes between the two? </p> <p>As for why the code never ends, it is probably because I don't have any <code>_exit()</code> or <code>exec()</code> statement explicitly for exit. Am I right?</p> <p><strong>UPDATE2:</strong><br> I just read: <a href="http://dev.fyicenter.com/Interview-Questions/UNIX/Difference_between_the_fork_and_vfork_system.html" rel="nofollow"><strong>56. Difference between the fork() and vfork() system call?</strong></a> and I think this article helps me with my first confusion.</p> <blockquote> <p>The child process from vfork() system call executes in the parent’s address space (this can overwrite the parent’s data and stack ) which suspends the parent process until the child process exits.</p> </blockquote>

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