fork

问题 The program terminates after taking 4 or 5 values from scanf . But I want it to accept 8 values (totaling 8 processes) and then terminate. void main() { fork(); fork(); fork(); scanf("%d",&j); printf("The values are %d\n",j); wait(0); } 回答1: Well, the first question you have to answer to yourself is how many processes you think you have there? As you don't use the returned value from the fork(2) system call, you don't know even if you are the parent or you are the child after execution of

问题 I have a problem, I would like to do a fork for example a fork of 20processes, this fork created, should not do anything until the last one is not created, and I want to do it with semaphore, how can I implement it? for (i=0; i<20; i++) { switch (fork()) { case: -1: exit(EXIT_FAILURE); case 0: execve(....); exit(EXIT_FAILURE); default: printf ("Child Created!"); } } 回答1: Here's you homework. You can pay me later. #include <semaphore.h> #include <sys/mman.h> #include <stdio.h> #include <stdlib

问题 Let's say I have a C program which spawns some child processes using fork() and exec() . The parent keeps a list of the pid s of its children. Once in a while, it tries wait ing on them using WNOHANG and informs the user if they have terminated. The program then decides to exit. Must I explicitly kill and then wait on the remaining child processes so that they don't become zombies? According to Wikipedia: "Zombie processes should not be confused with orphan processes: an orphan process is a

问题 In a C program, I have a menu, with some options to choose from, represented by characters. There's an option that forks the process, and runs a function (we can say it runs in the background). This function that runs in the background, under some conditions, can ask the user to enter data. My problem is: when the main process is asking for data (or option) and the child process is asking for data too, I can't send the data properly. Do you have any idea on how to deal with this? I'll add a

问题 I installed fork on my Ubuntu Server (using PHP-Apache-Codeigniter). I have this code: <?php public function add_keyword() { $keyword_p = $this->input->post('key_word'); $prod = $this->input->post('prod_name'); $prod = $this->kas_model->search_prod_name($prod); $prod = $prod[0]->prod_id; $country = $this->input->post('key_country'); $keyword = explode(", ", $keyword_p); var_dump($keyword); $keyword_count = count($keyword); echo "the keyword count: $keyword_count"; // Create fork $pid = pcntl

问题 I need to use Active_admin with Formtastic 2 and the main branch doesn't support it yet. A couple of weeks ago someone made a fork to support Formtastic 2 But then other additions were added to the master branch and were not commited to the fork. And now the fork is outdated with other things, but yet it support Formtastic. How can I merge both of them locally in my computer using git? 回答1: This simplest way is to switch to your local formtastic branch, then run git merge master to merge the

问题 This question already has answers here : Where is clone() method in sched.h on Mac OS X (2 answers) Closed 5 years ago . I would like to use the clone system call on OS X. It's a Unix system call so it shouldn't be a problem, right? I have successfully tried using fork , vfork and other similar functions. Here is the program I'm trying: #include <sched.h> //Clone resides here #include <stdlib.h> //standard library #include <stdio.h> #include <time.h> #include <limits.h> #include <sys/shm.h>

问题 I install ratchet php websocket. I do pcntl_fork in onMessage method to work with every client in new thread. public function onMessage(ConnectionInterface $from, $msg) { $pid = pcntl_fork(); if ($pid == -1) { $this->myPrint("cant create fork"); } else if ($pid) { } else { // ..... $result $from->send($result); // $pid = getmypid(); // exit($pid); } } if i try to close child process, client dont get any message. ($from->send($result) dont work). if i comment exit($pid) . Client get message.

问题 I created a server with Perl under Windows (ActivePerl 5.10.1 build 1006) that forks upon being connected to, accepts some JSON data, and writes it to a database. I am running into a problem after 64 clients connect to the server, the error message being "Resource is not available" when trying to fork. Running this code under Linux I found many defunct child process, which was solved by adding a wait() call on the parent. This however did not solve the problem. Running the code under Linux

问题 I have the following code: void fork1() { pid_t id, cpid; int status; id = fork(); if (id > 0) { // parent code cpid = wait(&status); printf("I received from my child %d this information %d\n", cpid, status); } else if (id == 0) { // child code sleep(2); exit(46); } else exit(EXIT_FAILURE); exit(EXIT_SUCCESS); } The output is: I received from my child -1 this information 0 So, why I receive the -1 error code after wait ? I was expecting to receive the value 46 as status. EDIT: I added the