signals

If by some miracle a segfault occurs in our program, I want to catch the SIGSEGV and let the user (possibly a GUI client) know with a single return code that a serious problem has occurred. At the same time I would like to display information on the command line to show which signal was caught. Today our signal handler looks as follows: void catchSignal (int reason) { std :: cerr << "Caught a signal: " << reason << std::endl; exit (1); } I can hear the screams of horror with the above, as I have read from this thread that it is evil to call a non-reentrant function from a signal handler. Is

How can I set a variable of type long (on 64 bit machine = 8 bytes) inside a signal handler? I've read that you can only use variables of type sig_atomic_t , which is actually implemented as volatile int inside a signal handler and it is unsafe to modify data types bigger than an int . You can use a long inside a signal handler, you can use anything, in fact. The only thing you should take care of is proper synchronization in order to avoid race conditions. sig_atomic_t should be used for variables shared between the signal handler and the rest of the code. Any variable "private" to the signal

I am trying to make a program that suspends its execution until a signal arrives . Then, after the signal arrives I just want my code to continue its execution from where it was . I don't want it to execute a function handler or whatsoever. Is there a simple way of doing this? I have been struggling for a week or so, reading here and there, and didn't manage to get a fully operative code. In particular, I want the main program to create a thread that waits for some particular event to happen (e.g., a user has input some data to stdin). Meanwhile, the main program is doing something but at some

I'm trying to learn how to use sigtimedwait(), but I find that it's not waiting for the timeout to complete. Below it seems to return EAGAIN 4s faster than it should (1s faster per 1min of timeout): #include <signal.h> #include <syslog.h> #include <stdarg.h> #include <stddef.h> #include <errno.h> int main(int argc, char* argv[]) { setlogmask(LOG_UPTO(LOG_NOTICE)); openlog ("SIG_TIMED_WAITER", LOG_CONS | LOG_PID | LOG_NDELAY, LOG_LOCAL1); syslog (LOG_NOTICE, "Started"); sigset_t set; sigemptyset(&set); sigaddset(&set, SIGUSR1); struct timespec to; to.tv_sec = 240; to.tv_nsec = 0; int ret =

I have created a few post_save signals but I was wondering if there will be performance issues later on. For example, I have something like this: def my_signal(sender, **kwargs): # some minimal processing posts = len(MyPosts.objects.filter(date__gte=variable)) if entries == "20": # crate an object and assign it to the post's author. post_save.connect(my_signal, sender=MyPosts) Let's say I have a very busy site and this is firing each time a post is created. Is it too bad to performance?. Is there a way to fire signals in a more slow-paced way (maybe, once a day or every few requests)?. UPDATE

I've put my signal receiver code in the respective model file. However, signal receivers keep growing and I'd like to separate them over multiple files. I haven't seen discussion on where to put signal receiver codes. (makes me suspect that I'm not supposed to make many signal receivers maybe?) See the docs: https://docs.djangoproject.com/en/1.8/topics/signals/#connecting-receiver-functions it's common to put them in a separate signals.py file, perhaps one per module in your project, but you need to ensure that these files get imported so that your signal receivers get registered. as detailed

First of all sorry for calling malloc inside signal handler :).I too understand we should not do any time consuming task/this kind of nasty stuff inside signal handler. But i am curious to know the reason why it is crashed ? #0 0x00006e3ff2b60dce in _lll_lock_wait_private () from /lib64/libc.so.6 #1 0x00006e3ff2aec138 in _L_lock_9164 () from /lib64/libc.so.6 #2 0x00006e3ff2ae9a32 in malloc () from /lib64/libc.so.6 #3 0x00006e3ff1f691ad in ?? () from .. i got similar core reported in https://access.redhat.com/solutions/48701 . operating system : RHEL P.P. malloc() is not a function that can be

Situation: I am writing a program in C that maintains a number of threads. Once a thread ends, a new one is created. Each thread forks - the child runs a process via exec() and the parent waits for it to finish. In addition, there is a signal handler thread that waits for signals. If SIGINT is detected then it tells the main thread to stop creating threads so eventually all the threads end and the program can exit. Signals are blocked in all threads except of course the signal handler thread. Aim: I want to be able to terminate the program by sending SIGTERM. This would work by stopping the