daemon | 易学教程

线程

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Python多线程编程(一）：threading 模块 Thread 类的用法详解我们进行程序开发的时候，肯定避免不了要处理并发的情况。一般并发的手段有采用多进程和多线程。但线程比进程更轻量化，系统开销一般也更低，所以大家更倾向于用多线程的方式处理并发的情况。 Python 提供多线程编程的方式。本文基于 Python3 讲解,Python 实现多线程编程需要借助于 threading 模块。所以，我们要在代码中引用它。 import threading threading 模块中最核心的内容是 Thread 这个类。我们要创建 Thread 对象,然后让它们运行，每个 Thread 对象代表一个线程，在每个线程中我们可以让程序处理不同的任务，这就是多线程编程。值得注意的是，程序运行时默认就是在主线程上创建 Thread 对象有 2 种手段。直接创建 Thread ，将一个 callable 对象从类的构造器传递进去，这个 callable 就是回调函数，用来处理任务。编写一个自定义类继承 Thread，然后复写 run() 方法，在 run() 方法中编写任务处理代码，然后创建这个 Thread 的子类。 1. 直接创建 Thread 对象。 class threading . Thread ( group = None , target = None ,

Can I have some code constantly run inside Django like a daemon

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问题 I'm using mod_wsgi to serve a django site through Apache. I also have some Python code that runs as a background process (dameon?). It keeps polling a server and inserts data into one of the Django models. This works fine but can I have this code be a part of my Django application and yet able to constantly run in the background? It doesn't need to be a process per se but a art of the Django site that is active constantly. If so, could you point me to an example or some documentation that

Does endless While loop take up CPU resources?

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问题 From what I understand, you write your Linux Daemon that listens to a request in an endless loop. Something like.. int main() { while(1) { //do something... } } ref: http://www.thegeekstuff.com/2012/02/c-daemon-process/ I read that sleeping a program makes it go into waiting mode so it doesn't eat up resources. 1.If I want my daemon to check for a request every 1 second, would the following be resource consuming? int main() { while(1) { if (request) { //do something... } sleep(1) } } 2.If I

Efficient Python Daemon

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问题 I was curious how you can run a python script in the background, repeating a task every 60 seconds. I know you can put something in the background using &, is that effeictive for this case? I was thinking of doing a loop, having it wait 60s and loading it again, but something feels off about that. 回答1: I think your idea is pretty much exactly what you want. For example: import time def do_something(): with open("/tmp/current_time.txt", "w") as f: f.write("The time is now " + time.ctime()) def

垃圾IDEA

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垃圾IDEA太不人性化了，做啥都不方便。看不惯他有干不死他。啥操作都不方便。今天建个Android项目。找半天都不知道咋运行。垃圾。网上都没教程。连建个空activity都不行。 org.gradle.api.ProjectConfigurationException: A problem occurred configuring root project 'MyApplication'. at org.gradle.configuration.project.LifecycleProjectEvaluator.addConfigurationFailure(LifecycleProjectEvaluator.java:94) at org.gradle.configuration.project.LifecycleProjectEvaluator.doConfigure(LifecycleProjectEvaluator.java:66) at org.gradle.configuration.project.LifecycleProjectEvaluator.access$100(LifecycleProjectEvaluator.java:34) at org.gradle.configuration.project.LifecycleProjectEvaluator

How to keep a persistent PHP script running?

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问题 I have a PHP script that listens for incoming socket requests, etc. I need this script to be continually running (it runs within an infinite loop) on the server. How can I initiate and manage this process? I tried just starting it up through SSH/putty but as soon as the SSH connection times out the script dies. 回答1: myscript.php & This will run the scriptin the background you can check it with ps aux | grep myscript.php As Patrick has mentioned in the comments below, there is no maximum

How to package a Python daemon with setuptools

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问题 How do you package a Python app with setuptools so that when it's installed (e.g. via setup.py or pip), it places a daemon script in the appropriate location, starts it, and marks it to automatically start at boot time? In my case, my code only works with Linux, so I only care about installing the daemon in Linux environments (specifically Ubuntu). I've found several posts describing how to easily create Python daemons, but I can't seem to find anything describing how you'd install them in a

Best way to daemonize Java application on Linux [closed]

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问题 Closed . This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 6 years ago . While I found this question being answered here on SW several times, I didn't find a concluding answer what is the best approach. I'm not looking to use any external wrapper, as I found them launching the java process under a nice level lower then themselves which potentially

Why MUST detach from tty when writing a linux daemon?

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问题 When i tried to write a daemon under linux using C, i was told i should add following code after fork code block: /* Preparations */ ... /* Fork a new process */ pid_t cpid = fork(); if (cpid == -1){perror("fork");exit(1);} if (cpid > 0){exit(0);} /* WHY detach from tty ? */ int fd = open("/dev/tty", O_RDWR); ioctl(fd, TIOCNOTTY, NULL); /* Why set PGID as current PID ? */ setpgid(getpid(), 0); My question is: Is there a must to do the above operations? 回答1: You must disassociate your daemon

How to write a Java daemon

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问题 This will be a network application that will always (or near as always as I can manage) be listening on a given port. I'm fairly new to Java, and very new to non-web server side programming, so I'd like to get feedback from the community on my assumptions and preliminary plans. I've read about jsvc ( http://commons.apache.org/daemon/jsvc.html ) and am currently operating on the assumption that this is the "best" way to write a daemon in java for a linux box (likely running centOS). Can nagios