fork | 易学教程

Why getppid() from the child return 1

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问题 I was running the program #include<stdio.h> #include <unistd.h> main() { pid_t pid, ppid; printf("Hello World1\n"); pid=fork(); if(pid==0) { printf("I am the child\n"); printf("The PID of child is %d\n",getpid()); printf("The PID of parent of child is %d\n",getppid()); } else { printf("I am the parent\n"); printf("The PID of parent is %d\n",getpid()); printf("The PID of parent of parent is %d\n",getppid()); } } THe output I got was. $ ./a.out Hello World1 I am the parent The PID of parent is

Does this multiple pipes code in C makes sense?

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问题 I've created a question about this a few days. My solution is something in the lines of what was suggested in the accepted answer. However, a friend of mine came up with the following solution: Please note that the code has been updated a few times (check the edit revisions) to reflect the suggestions in the answers below. If you intend to give a new answer, please do so with this new code in mind and not the old one which had lots of problems. #include <stdio.h> #include <stdlib.h> #include

Get the copy-on-write behaviour of fork()ing, without fork()

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问题 I have a large buffer: char *buf = malloc(1000000000); // 1GB If I forked a new process, it would have a buf which shared memory with the parent's buf until one or the other wrote to it. Even then, only one new 4KiB block would need to be allocated by the kernel, the rest would continue to be shared. I'd like to make a copy of buf, but I'm only going to change a little of the copy. I'd like copy-on-write behaviour without forking. (Like you get for free when forking.) Is this possible? 回答1:

idea 打包的jar运行报 “XXX中没有主清单属性”

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今天得打包发布到测试服务器上我就用IDEA打了一个jar包然后到服务器上运行就显示报错误：找不到或无法加载主类我就想不通了搞了好几次还是不行人家说什么配置第二个还是没什么用 -------------------------------------------------- -----------------用MAVEN打包---- -------------------------------------------------- ---------------------- 我决定换一种方式用行家打包试试看！ <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> <configuration> <fork>true</fork> </configuration> </plugin> </plugins> </build> 然后在maven这里执行【最好先clean一下在打包】看控制台在用java -jar xxx.jar 好项目成功启动！来源： CSDN 作者： qq号614617158 链接： https://blog.csdn.net/qq_38092788/article

Fork Gist to Repo on GitHub

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问题 I have a bunch of templates I made in Gist form so people can discuss them at the bottom. We like to copy these files and paste them into a repo and make an addon there. Is it possible to fork a Gist to Repo via the GitHub site or client? If not either of those two, can it be done via shell? 回答1: New Correct Answer Yes, directly! Go to https://github.com/new/import and put in the URL of your gist and a name for your new repo. I just put in https://gist.github.com/RichardBronosky

Just check status process in c

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问题 I want to know the status of a process. I think I can use the wait family functions but actually I don't want to wait for the process, just check the status and go on. I would want something like checkStatusOfProcess(&status); if(status == WORKING) { //do something } else if(status == exited) { //do something else } else \\I dont care about other states 回答1: Then you want to use the waitpid function with the WNOHANG option: #include <sys/types.h> #include <sys/wait.h> int status; pid_t return

How to exit a child process and return its status from execvp()?

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问题 In my simple custom shell I'm reading commands from the standard input and execute them with execvp(). Before this, I create a fork of the current process and I call the execvp() in that child process, right after that, I call exit(0). Something like this: pid = fork(); if(pid == -1) { perror("fork"); exit(1); } if(pid == 0) { // CHILD PROCESS CODE GOES HERE... execvp(pArgs[0], pArgs); exit(0); } else { // PARENT PROCESS CODE GOES HERE... } Now, the commands run with execvp() can return

redux-saga细说

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参考： https://blog.csdn.net/sinat_17775997/article/details/103524043 https://www.jianshu.com/p/6f96bdaaea22 redux-saga 中常见的几种模式(翻译)https://www.jianshu.com/p/c3425f9ef6b7 take([...]) 和 race 的比较重要的语境区别是： take([...]) 是等待第一个相匹配的action的到达 race 是等待第一个 racing-effect 的完成 1.概述 Redux-saga是一个用于管理 Redux 应用异步操作的中间件（又称异步action）本质都是为了解决异步action的问题 Redux Saga可以理解为一个和系统交互的常驻进程，这个线程可以通过正常的Redux Action从主应用程序启动，暂停和取消，它能访问完整的Redux state，也可以dispatch Redux Action。一个 Saga 就像是应用程序中一个单独的线程，它独自负责处理副作用。其中，Saga可简单定义如下的公式： Saga = Worker + Watcher 2.简单使用 redux-saga本质是一个可以自执行的generator。在 redux-saga 中，UI 组件自身从来不会触发任务

How's Python Multiprocessing Implemented on Windows?

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问题 Given the absence of a Windows fork() call, how's the multiprocessing package in Python 2.6 implemented under Windows? On top of Win32 threads or some sort of fake fork or just compatibility on top of the existing multithreading? 回答1: It's done using a subprocess call to sys.executable (i.e. start a new Python process) followed by serializing all of the globals, and sending those over the pipe. A poor man's cloning of the current process. This is the cause of the extra restrictions found when

Forking in PHP on Windows

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问题 We are running PHP on a Windows server (a source of many problems indeed, but migrating is not an option currently). There are a few points where a user-initiated action will need to kick off a few things that take a while and about which the user doesn't need to know if they succeed or fail, such as sending off an email or making sure some third-party accounts are updated. If I could just fork with pcntl_fork() , this would be very simple, but the PCNTL functions are not available in Windows