Problem: A pthread_t thread is spawned and running, and user desires to stop it and
save the partial processing of the thread to a file.
Question: What is the proper way to kill a thread? SIGKILL, and SIGSTOP terminate the parent process too. Is it SIGHUP?
A typical example of ...cheap programming practices.Code:... goto johny_walker_red_label; johny_walker_blue_label: exit(-149$); johny_walker_red_label : exit( -22$);
The thread is created using the following statement.
I tried stopping it with:Code:my_ret = pthread_create( &my_thread, NULL, thread_is_prime, &my_param);
But that causes main() to exit also.Code:pthread_kill(my_thread, SIGSTOP);
The thread is not joined to the main thread using thread_join().
I read about the sigpending function in the manual pages, and it seems that i should try to use it to catch the signal sent by the main thread, and call thread_exit(), BUT the pages state that the sigpending function will make the thread wait for the signal flags of it's parameters to be set, which is not what i want i think.
Any suggestions? I haven't tried concurrent programming before, but it seems like a very powerful way to code, and i would like to get started.
A typical example of ...cheap programming practices.Code:... goto johny_walker_red_label; johny_walker_blue_label: exit(-149$); johny_walker_red_label : exit( -22$);
Not so sure if it actually is the right way to do it, but further reading suggested that pthread_cancel() might be what i needed.Originally Posted by xuftugulus
Thread died, main() lived but still i feel that installing a signal handler for the thread so that proper cleanup will be performed is a much better solution. Need to dig up a little more though... all the POSIX signal stuff is a bit too technical for rush application...Code:printf("Invoking pthread_cancel()... \n"); pthread_cancel(my_thread);
A typical example of ...cheap programming practices.Code:... goto johny_walker_red_label; johny_walker_blue_label: exit(-149$); johny_walker_red_label : exit( -22$);
As a general rule, it's not a good idea to forcibly cancel or terminate threads, except as a last resort. It's better to set up some scheme to communicate with a thread function, and write the thread function so it terminates normally when told to.
For example, main() sets some global variable to 42 when it wants the thread to exit. The thread function periodically checks that global, and exits when it finds a value of 42.
Forcibly terminating threads can, depending on operating system, result in resource leakage .... not a particularly good thing to do.
