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POC Seconds ticking failing when need to process queries?
 

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  1. POC Seconds ticking failing when need to process queries?
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    <p>We have a code a below where it keep ticking for every second it works perfectly fine. The problem starts when we have //select and insert queries need to be process for each and every second we notice there is at time gaps between 1 to 10 seconds. Thus we practically miss some processing to be done. Any idea how to overcome this? Is it that we need to create a separate thread on each second is it?Thank you.</p> <pre><code>void * reader_thread (void * arg) { while (1) { if (flag) { struct timeval tv; char timeBuf[10],secondBuf1[100],queryBuf1[500],queryBuf2[500]; char buff[20] = {0}; gettimeofday (&amp;tv, NULL); //fprintf (stderr, "[%d.%06d] Flag set to 1 on ", tv.tv_sec, tv.tv_usec); tv.tv_sec -= 5; strftime(buff, 20, "%Y-%m-%d %H:%M:%S", localtime(&amp;tv.tv_sec)); printf("\nTime is %s", buff); //select and insert queries fprintf (stderr, " %s\n", buff); flag = 0; } usleep (100); // will skew the processing but not signal delivery } return NULL; } void callback (int sig) { flag = 1; // this is the only thing the callback does } int main () { timer_t tid = 0; pthread_t thread; struct itimerspec it; char *localServer = "localhost", *remoteServer = "localhost"; char *localUser = "user1", *remoteUser = "user2"; char *localPassword = "****", *remotePassword = "*****"; char *localDatabase = "db1", *remoteDatabase = "db1"; localConn = mysql_init(NULL), remoteConn = mysql_init(NULL); if (!mysql_real_connect(localConn, localServer, localUser, localPassword, localDatabase, 0, NULL, 0)) { fprintf(stderr, "%s\n", mysql_error(localConn)); exit(1); } pthread_create (&amp;thread, NULL, reader_thread, NULL); signal (SIGALRM, callback); it.it_value.tv_sec = 1; it.it_value.tv_nsec = 0; it.it_interval.tv_sec = 1; it.it_interval.tv_nsec = 0; timer_create (CLOCK_REALTIME, NULL, &amp;tid); timer_settime (tid, 0, &amp;it, NULL); while (1) sleep (100); return 0; } </code></pre> <p>Edit codes.</p> <pre><code>sigset_t sigset; sigfillset(&amp;sigset); if (pthread_sigmask( SIG_BLOCK, &amp;sigset, NULL)) { perror("pthread_sigmask"); } pthread_create (&amp;thread, NULL, reader_thread, NULL); //sigset_t sigset; //sigemptyset(&amp;sigset); sigaddset(&amp;sigset, SIGALRM); if (pthread_sigmask( SIG_UNBLOCK, &amp;sigset, NULL)) { perror("pthread_sigmask"); } </code></pre>
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      1. POC Seconds ticking failing when need to process queries?
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    1. COThe way you use signals is not optimal: 1 Verbatim from `man signal`: `The effects of signal() in a multithreaded process are unspecified.` 2 `sleep()` and `usleep()` will be interupted if the thread which called them receives a signal. 3 It is not specified which thread will receive `SIGALRM`.
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      1. POC Seconds ticking failing when need to process queries?
      1. USalk
 

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