fork

问题 I have an assignment which gives me this code to transform into a code that makes the parent process wait for all children processes to finish. PS: the first code has 4 processes and needs to use waitpid to solve this. #include <stdio.h> #include <stdlib.h> #include <sys/types.h> #include <unistd.h> int main(){ pid_t p = fork(); pid_t k = fork(); if(p>0){ printf("p=%d: PID = %d\n", p, getpid()); sleep(45); exit(0); } else if(p==0){ printf("p=%d: PID = %d\n", p, getpid()); exit(0); } else if(p

问题 I have an assignment which gives me this code to transform into a code that makes the parent process wait for all children processes to finish. PS: the first code has 4 processes and needs to use waitpid to solve this. #include <stdio.h> #include <stdlib.h> #include <sys/types.h> #include <unistd.h> int main(){ pid_t p = fork(); pid_t k = fork(); if(p>0){ printf("p=%d: PID = %d\n", p, getpid()); sleep(45); exit(0); } else if(p==0){ printf("p=%d: PID = %d\n", p, getpid()); exit(0); } else if(p

问题 I've found several methods to kill a child process. I would like to use the os.kill(pid). But it doesn't work, I guess it should though. def onExit(): os.kill(logProc, 0) QtCore.QCoreApplication.instance().quit return button.clicked.connect(onExit) logProc=os.fork() if logProc>0: proc() 回答1: You should pass signals like signal.SIGKILL (9), signal.SIGTERM (15) to kill the process. import signal ... os.kill(logProc, signal.SIGKILL) According to Linux kill(2) : If sig is 0 , then no signal is

问题 I've found several methods to kill a child process. I would like to use the os.kill(pid). But it doesn't work, I guess it should though. def onExit(): os.kill(logProc, 0) QtCore.QCoreApplication.instance().quit return button.clicked.connect(onExit) logProc=os.fork() if logProc>0: proc() 回答1: You should pass signals like signal.SIGKILL (9), signal.SIGTERM (15) to kill the process. import signal ... os.kill(logProc, signal.SIGKILL) According to Linux kill(2) : If sig is 0 , then no signal is

问题 I am trying to write a c++ program that creates a child process, runs a command and pipes the output back to the input of a command the parent is running. I have the parent execute the wait(NULL) or wait((void*)pid) command but it does not wait. here is the code: #include <string.h> #include <fstream> #include <iostream> #include <unistd.h> #include <stdio.h> #include <sys/wait.h> using namespace std; int main(int argc, char * argv[]) { char* commands[strlen(argv[1])]; char *command = NULL;

问题 Python guru I need your help. I faced quite strange behavior: empty python Process hangs on joining . Looks like it forks some locked resource. Env: Python version: 3.5.3 OS: Ubuntu 16.04.2 LTS Kernel: 4.4.0-75-generic Problem description: 1) I have a logger with thread to handle messages in background and queue for this thread. Logger source code (a little bit simplified). 2) And I have a simple script which uses my logger (just code to display my problem): import os from multiprocessing

问题 Python guru I need your help. I faced quite strange behavior: empty python Process hangs on joining . Looks like it forks some locked resource. Env: Python version: 3.5.3 OS: Ubuntu 16.04.2 LTS Kernel: 4.4.0-75-generic Problem description: 1) I have a logger with thread to handle messages in background and queue for this thread. Logger source code (a little bit simplified). 2) And I have a simple script which uses my logger (just code to display my problem): import os from multiprocessing

问题 I'm stuck on a problem in a C program on Linux. I know that when a processes is forked the child process inherits some things from the parent, including open file descriptors. The problem is that I'm writing a multi-process server application with a master process that accepts new connections and puts the descriptors into shared memory. When the child process attempts to read from one of these descriptors from the shared memory, on select() i got an EBADF error! How can the child process read

问题 * SOLUTION IN THE ANSWER BELOW * I got a problem with limiting childs in the multifork php script... Seems like last child never ends... I'm really tired and can't find the error, could You please help? It does not end most of times... <?php declare(ticks = 1); $max=5; $child=0; function sig_handler($signo) { global $child; switch ($signo) { case SIGCHLD: $child -= 1; echo "[-]"; } } pcntl_signal(SIGCHLD, "sig_handler"); $found = array(1,2,3,4,5,6,7,8,9,10,11,12); echo "LETS GO!\n"; foreach(

问题 I'm working on a sample program to learn how pipes and forking works. In my very basic implementation, in my child process, i closed 0 and duplicated the read end of the pipe so that file descriptor 0 is now the read end of my pipe. From my parent process, I write out a string, and in my child process, I read the string using cin as cin essentially is my read end of the pipe and what I observe is the complete string does not print out and I can't seem to understand why! #include <iostream>