signals

问题 My child proccess can't start to work. I need to pass signal and execute readUsual function. This is a small piece of code: int main() { pid_t pid2 = fork(); if (pid2 < 0) printf("Can't create child process\n"); else if (pid2==0) { //this block never execute printf("Process2, pid=%d\n",getpid()); signal(SIGUSR1,readUsual); } else { kill(pid2,SIGUSR1); printf("%s\n","Proccess1 end"); for(;;); } return 0; } 回答1: You need to either add synchronization in some way, or call signal() before your

问题 I've started using boost::signals2 instead of my old signals-code. I'm having a problem with administering multiple connections though. Here's my problem: I have many instances of the class Person: class Person { public: void SetName (string new_name) { name = new_name; NameChange (name); } string name; boost::signals2::signal<Person*> NameChange; }; I also have a people-browser, that must monitor a subset of all available people for changes. Since people can come and go from that subset I

问题 #include<stdio.h> #include<signal.h> void handler(int signo) { printf("Into handler\n"); while(1); } int main() { struct sigaction act; act.sa_handler = handler; act.sa_flags = 0; sigemptyset(& act.sa_mask); sigaction(SIGINT, &act, NULL); while(1); return 0; } After catching the KeyboardInterrupt once, when I press "Ctrl+C" again, SIGINT is not handled... I intend that "Into handler" should be printed each time I press "Ctrl+C" . I want to catch SIGINT inside the "SIGINT handler()" itself..

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 5 years ago . Why might somebody choose to use sigsetjmp instead of setjmp in C? I read in a book that there are some disadvantages in using setjmp with signal-related code, so the sigsetjmp function was implemented. Can anybody explain this with an example? Thanks in Advance. 回答1: See section 10.15 in “Advanced Programming

问题 I have a simple script trap 'echo exit' EXIT while true; do sleep 1; done and it behaves differently in different shells: $ bash tst.sh ^Cexit $ dash tst.sh ^C $ zsh tst.sh ^C $ sh tst.sh ^Cexit So I'm not sure about how it should operate and whether it is specified at all. 回答1: The EXIT trap isn't working the same way in every shell. A few examples: In dash and zsh it's only triggered by a regular exit from within the script. In zsh, if you trap a signal that would normally quit the

问题 Any ideas on this? Is there some kind of a signal queue, or does it get dropped? While we are at this question, is it true that signal handlers should do as minimal work as possible? I read somewhere that a signal handler should use a pipe and just write one byte to it, indicating what the program should do. Then somewhere else the program periodically checks the pipe, and dispatches based on byte in it. (I might have misunderstood it) Thanks, Boda Cydo. 回答1: To answer the second part of your

问题 Heroku may send a SIGTERM to your application for various reasons, so I have created a handler to take care of some cleanup in case this happens. Some googling hasn't yielded any answers or examples on how to test this in RSpec. Here's the basic code: Signal.trap('TERM') do cleanup end def cleanup puts "doing some cleanup stuff" ... exit end What's the best way to test that this cleanup method is called when the program receives a SIGTERM? 回答1: Kill yourself! Send the signal to RSpec with

问题 When one process sends a signal to another process, under what circumstances does receiving process wait until it is rescheduled to run? Under what circumstances does the installed signal handler get invoked immediately? How much overhead does the process incur when raising a signal compared to just call the corresponding signal handler directly? 回答1: About delivery of signals, TLPI states that signals are "normally" delivered when a task is next scheduled, when switching from kernel mode to

问题 I am trying to use SIGRTMIN signal to create blocking signalhandler in Android NDK. int startThread(){ pthread_t thread; sigset_t set; /* Block SIGRTMIN other threads created by main() will inherit a copy of the signal mask. */ sigemptyset(&set); int rc = sigaddset(&set, SIGRTMIN); __android_log_print(ANDROID_LOG_DEBUG, "LOG", "Return Code:%d",rc); __android_log_print(ANDROID_LOG_DEBUG, "LOG", "Error Code:%d",errno); pthread_sigmask(SIG_BLOCK, &set, NULL); pthread_create(&thread, NULL, &sig

问题 I am using Python (2.7) SocketServer with ForkingMixIn. It worked well. However sometimes on heavy usage (tons of rapidly connecting/disconnecting clients) the "server" stuck, consuming all the idle CPU (shown 100% CPU by top). If I use strace from CLI on the process it shows it does endless sequence of waitpid() syscall. According to command "ps" there are no child processes though at this point. After this problem my server implementation goes unusable and only its restarting helps :(