pthread_join from a signal handler

Posted by liv2hak on Stack Overflow See other posts from Stack Overflow or by liv2hak
Published on 2014-06-03T21:13:06Z Indexed on 2014/06/03 21:24 UTC
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I have a capture program which in addition do capturing data and writing it into a file also prints some statistics.The function that prints the statistics

static void* report(void)
{
         /*Print statistics*/
}

is called roughly every second using an ALARM that expires every second.So The program is like

void capture_program()
{
       pthread_t report_thread

            while(!exit_now)
            {
                     if(pthread_create(&report_thread,NULL,report,NULL)){
                            fprintf(stderr,"Error creating reporting thread! \n");
                     }

                     /*
                        Capturing code
                        --------------
                        --------------
                      */
                      if(doreport)
                             usleep(5);


            }
}

void *report(void *param)
{
       while(true)
       {
            if(doreport)
            {
                   doreport = 0
                   //access some register from hardware
                   usleep(5)
            }
       }

}

The expiry of the timer sets the doreport flag.If this flag is set report() is called which clears the flag.I am using usleep to alternate between two threads in the program.This seems to work fine. I also have a signal handler to handle SIGINT (i.e CTRL+C)

static void anysig(int sig) { if (sig != SIGINT) dagutil_set_signal_handler(SIG_DFL);

/* Tell the main loop to exit */
exit_now = 1;
return;

}

My question:

1) Is it safe to call pthread_join from inside the signal handler?
2) Should I use exit_now flag for the report thread as well?

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