fork | 易学教程

How can I signal a forked child to terminate in Perl?

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问题 How can I make the same variable shared between the forked process? Or do I need to write to a file in the parent then read the value saved to the file in the child once the file exists? $something never appears to get set in this so it just loops in the sleep my $something = -1; &doit(); sub doit { my $pid = fork(); if ($pid == 0) { while ($something == -1) { print "sleep 1\n"; sleep 1; } &function2(); } else { print "parent start\n"; sleep 2; $something = 1; print "parent end: $something\n"

Why doesn't child process continue running after receiving signal?

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The following is my code. Parent forks a child. Child pause until parent sends a signal to it, then it continues running. My question is why doesn't child process continue running after parent sending signal to him. Did I miss or misunderstand something? #include<stdio.h> #include<unistd.h> #include<signal.h> void sigusr1( int pidno ) { printf("Catched\n"); } int main() { pid_t pid; signal( SIGUSR1, sigusr1 ); if( (pid = fork()) == 0 ){ pause(); printf("Child\n"); } kill( pid , SIGUSR1 ); //parent sends signal to child pause(); } Here's what happens in the parent: Fork a child. Send SIGUSR1 to

How do I generate coverage reports for fork()'d children using gcov/lcov?

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问题 I'm having trouble generating coverage reports for a project of mine -- it seems that the lines in the child process after a fork are never hit, althought they clearly are in reality. Here is the coveralls report of the forking part (The results are the same with lcov+genhtml), and the build logs. The project uses autotools with libtool to build, and packs everything as a static library. (configure.ac, library makefile.am, tests makefile.am) I tried to add the coverage flags to the tests, and

How can Perl share global variables in parallel processing?

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use Parallel::ForkManager; use LWP::Simple; my $pm=new Parallel::ForkManager(10); our $a =0; @LINK=( 10,203, 20, 20 ,20 ,10 ,101 ,01 ,10 ) ; for my $link (@LINK) { $pm->start and next; my $lo = ($link * 120.22 )*12121.2121212121212121*( 12121212.1212121+ $link); $a = $a+ $lo ; print $a."\n" ; $pm->finish; }; print $a ; I was trying to access the global variable on parallel process using parallel fork manager module . end of the program the global variable still remaining same .. how to achieve this ? whether its is possible ? If the program wasn't starting parallel processes, then the problem

How to fork processes in R

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问题 I'm trying to understand the forking system implemented by R's multicore package. The package example is: p <- fork() if (inherits(p, "masterProcess")) { cat("I’m a child! ", Sys.getpid(), "\n") exit(,"I was a child") } cat("I’m the master\n") unserialize(readChildren(1.5)) but it doesn't seem to work when pasted in the R interactive console. Does anyone have an example of using fork() with R's multicore or parallel packages? 回答1: The fork example in the multicore package 'works for me' ; try

os.execute without inheriting parent's fds

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问题 I have a problem analogous to the one described here: Prevent fork() from copying sockets Basically, inside my Lua script I'm spawning another script which: doesn't require communicating with my script either way continues running after my script had finished is a 3rd party program, code of which I have no control over The problem is that my Lua script opens a TCP socket to listen on a specific port and after it's quit and despite an explicit server:close() the child (or more specifically its

Recursive Fibonacci using Fork (in C)

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问题 I'm attempting to write a function that recursively computes the resulting fibonacci number from a given int n using forks in C. Here is the function specification: If print is true, print it. Otherwise, provide it to the parent process. The solution should be recursive and it must fork a new child for each call. Each process should call doFib() exactly once. The method signature cannot be changed. Helper functions cannot be used. Here is what I've written thus far based on my understanding

Fork, Ruby, ActiveRecord and File Descriptors on Fork

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问题 I understand that when we fork a process the child process inherits a copy of the parents open file descriptors and offsets. According to the man pages this refers to the same file descriptors used by the parent. Based on that theory in the following program puts "Process #{Process.pid}" file = File.open('sample', 'w') forked_pid = fork do sleep(10) puts "Writing to file now..." file.puts("Hello World. #{Time.now}") end file.puts("Welcome to winter of my discontent #{Time.now}") file.close

pipe() and fork() in c

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问题 I need to create two child processes. One child needs to run the command "ls -al" and redirect its output to the input of the next child process, which in turn will run the command "sort -r -n -k 5" on its input data. Finally, the parent process needs to read that (data already sorted) and display it in the terminal. The final result in the terminal (when executing the program) should be the same as if I entered the following command directly in the shell: "ls -al | sort -r -n -k 5". For this

Proper fork() and pipe() use for a single parent having multiple children. How do I do this right?

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So, my PREVIOUS POST was flagged for being off topic, too vague, and asking for opinions and recommendations for useful code. It did those things, so I am re-posting as a question on code I am working on. Thanks to those in the previous post, I was able to piece what I have here from reviewing what you guys said. The focus here is the Parent/Child relationship and the use of fork() and pipe() to get the desired affect. The project is a POSIX card game where the parent (dealer) forks into 5 children (players) with their own pipe from the parent. The parent deals cards to the players (at least 5