kill thread which is with block function... (fgets...)

I am writing a video program in C in embedded linux.
My main function creates 2 threads.
All are with while loop.
(1)main loop is in charge with video processing
(2)thread 1 loop is in charge with User Interface
(2)thread 2 loop is in charge with statistic of video

My question is ,
How do i terminate this program by others normally with
thread 1 is with blocking function?( fgets is always waiting for user input )
( Our design is with this program could be terminated by other program. )

PS1. I tried to add a SIGINT callback function in this program.But this thread 1 is still pending there waiting fo user input even if i pass SIGINT to it...

PS2. "kill -9" make my program crash occasionally.
( don't know why...maybe thread 1 do not release
resources normally... )

Any ideas for this?

When you say "tried to add a SIGINT callback function", do you mean that you added a signal handler, and if so, did you use sigaction?

Originally Posted by okeyla I am writing a video program in C in embedded linux. My main function creates 2 threads. All are with while loop. (1)main loop is in charge with video processing (2)thread 1 loop is in charge with User Interface (2)thread 2 loop is in charge with statistic of video My question is , How do i terminate this program by others normally with thread 1 is with blocking function?( fgets is always waiting for user input ) ( Our design is with this program could be terminated by other program. ) PS1. I tried to add a SIGINT callback function in this program.But this thread 1 is still pending there waiting fo user input even if i pass SIGINT to it... PS2. "kill -9" make my program crash occasionally. ( don't know why...maybe thread 1 do not release resources normally... ) Any ideas for this?

The appropriate way to manage a multi-threaded application is to set up a run flag. When it's time for the application to exit, clear the run flag that the independent threads have been coded to read and quit if the flag is clear.

But don't expect to be able to force the threads to quit. Write your thread code so the threads only continue to execute by testing the run flag and continuing on that basis:

while(ok_to_run) {
   // busy work here
}

When it's time to exit, clear the "ok_to_run" flag, then join the relevant thread(s) so the main application won't exit before the threads do.