Send a SIGTERM or a SIGKILL to it: http://en.wikipedia.org/wiki/SIGKILL http://en.wikipedia.org/wiki/SIGTERM SIGTERM is polite and lets the process clean up before it goes, whereas, SIGKILL is for when it won’t listen >:) Example from the shell (man page: http://unixhelp.ed.ac.uk/CGI/man-cgi?kill ) kill -9 pid In C, you can do the same thing using the kill syscall: kill(pid, … Read more
What is the advantage that is achieved by using this combo (instead of some other solution) that makes people still use this even though we have waste? You have to create a new process somehow. There are very few ways for a userspace program to accomplish that. POSIX used to have vfork() alognside fork(), and … Read more
Valgrind follows forked processes when given the –trace-children=yes option. You should be able to achieve this by using suitable filters. No. Valgrind hooks into the module loading code using LD_PRELOAD, so attaching to a running process is not possible.
The child process inherits signal handlers from the parent, but not the pending signal. After forking try installing the signal handler for SIGTRAP at a place in code where the child process executes after forking. If you don’t handle SIGTRAP, the default action is that the child is terminated. If you want to debug the … Read more
There’s a tradeoff between 3 multiprocessing start methods: fork is faster because it does a copy-on-write of the parent process’s entire virtual memory including the initialized Python interpreter, loaded modules, and constructed objects in memory. But fork does not copy the parent process’s threads. Thus locks (in memory) that in the parent process were held … Read more
In C there are some differences however: fork() Purpose is to create a new process, which becomes the child process of the caller Both processes will execute the next instruction following the fork() system call Two identical copies of the computer’s address space,code, and stack are created one for parent and child. Thinking of the … Read more
You should definitely use _Exit(). exit() calls the functions you added with atexit() and deletes files created with tmpfile(). Since the parent process is really the one that wants these things done when it exists, you should call _Exit(), which does none of these. Notice _Exit() with a capital E. _exit(2) is probably not what … Read more
How it works is largely irrelevant – as a developer working at a certain level (ie, coding to the UNIX APIs), you really only need to know that it works. Having said that however, and recognising that curiosity or a need to understand at some depth is generally a good trait to have, there are … Read more
That C program is tiny, seriously tiny. In addition, fork()’ing a program like that is very, very efficient. An interpreter, such as Bash, however, is much more expensive in terms of RAM usage, and needs to access the disk all the time. Try running it for much longer. 🙂
The problem is that fork() only copies the calling thread, and any mutexes held in child threads will be forever locked in the forked child. The pthread solution was the pthread_atfork() handlers. The idea was you can register 3 handlers: one prefork, one parent handler, and one child handler. When fork() happens prefork is called … Read more