Îïèñàíèå îøèáêè îò 19.12.2005. Èíòåðâàëüíûé òàéìåð íåïðàâèëüíî íà ñèñòåìàõ ñ NPTL

Ñôîðìèðîâàëîñü ïîäîçðåíèå íà áàãó â ðàáîòå èíòåðâàëüíîãî òàéìåðà è ñèãíàëîâ â NPTL íà ÿäðàõ >= 2.6.12.
Ïðîáëåìà â ñëåäóþùåì:

• èìååòñÿ çàäà÷à â êîòîðîé ñîçäà¸òñÿ ìíîæåñòâî ïîòîêîâ;
• êàæäûé ïîòîê ñîçäà¸ò ñîáñòâåííûé èíòåðâàëüíûé òàéìåð ñ èíäèâèäóàëüíûì ïåðèîäîì ñ ïîìîùüþ ôóíêöèé: setitimer() èëè timer_create();
• îáðàáîò÷èê ñèãíàëîâ äëÿ âñåõ ýòî ôóíêöèÿ ïóñòûøêà óêàçàííàÿ ñ ïîìîùüþ: signal();
• êàæäûé ïîòîê öèêëè÷åñêè âûïîëíÿåò ñâîé êîä ñ îæèäàíèåì ñèãíàëà ïîñëå ýòîãî ñ ïîìîùüþ ôóíêöèé: sigwait() èëè pause();
• íà ñèñòåìàõ áåç NPTL è íà ñèñòåìàõ ñ NPTL íà ÿäðàõ 2.4 (ALTLinux2.4, ASPLinux9) ñèãíàëû øëþòñÿ ïîòîêàì è îíè ïåðèîäè÷åñêè âûïîëíÿþò ñâîé êîä;
• íà ñèñòåìàõ ñ NPTL è ÿäðàìè >= 2.6.12 (SuSE10_64, Mandriva2006, FedoreCore4_64) ñèãíàëû øëþòñÿ ïðîöåññó, íî íå ïîòîêàì, â ðåçóëüòàòå ÷åãî ïîòîêè ñòîÿò íà îæèäàíèè ñèãíàëà;

Äëÿ ïðèìåðà íàïèñàíà òåñòîâàÿ ïðîãðàììà êîòîðàÿ âîñïðîèçâîäèò ýòó ïðîáëåìó. Íà ñèñòåìàõ áåç NPTL è íà ñèñòåìàõ ñ NPTL íà ÿäðàõ 2.4 (ALTLinux2.4, ASPLinux9) ðåçóëüòàòû å¸ ðàáîòû òàêèå:

ALTLinux2.4

roman@roman my]$ ./a.out Pthread inteval timer test. Pthread inteval timer test. Pthread inteval timer test. Pthread inteval timer test. Pthread inteval timer test. Pthread inteval timer test. Pthread inteval timer test. Pthread inteval timer test. Pthread inteval timer test. Pthread inteval timer test. Pthread inteval timer test. Pthread inteval timer test. Pthread inteval timer test. Pthread inteval timer test. Pthread inteval timer test.
//

Íà ñèñòåìàõ ñ NPTL è ÿäðàìè >= 2.6.12 (SuSE10_64, Mandriva2006, FedoreCore4_64) ðåçóëüòàòû å¸ ðàáîòû òàêèå:

SuSE 10 (64)

roman@roman:~/Documents> ./a.out Pthread inteval timer test. Signal test: 10. Exit from programm! Signal test: 10. Exit from programm! Signal test: 10. Exit from programm! Signal test: 10. Exit from programm! Signal test: 10. Exit from programm! Signal test: 10. Exit from programm! Signal test: 10. Exit from programm! Signal test: 10. Exit from programm! Signal test: 10. Exit from programm! Signal test: 10. Exit from programm! Signal test: 10. Exit from programm! Signal test: 10.

Èç ïðîòîêîëà âûïîëíåíèÿ ïðîãðàììû íà SuSE10 âèäíî ÷òî:

• öèêë ïîòîêà îäèí ðàç âûïîëíÿåòñÿ è ñòîïîðèòñÿ íà îæèäàíèè ñèãíàëà ôóíêöèåé sigwait(&set, &sig);
• ïðè ýòîì ñèãíàëû èäóò, íî íà ïðîöåññ, ÷òî âèäíî ïî ñîîáùåíèÿì "Exit from programm!" âîçíèêàþùèõ ïîñëå ôóíêöèè sleep(30) ñ ÷àñòîòîé 1 ñåê ïóò¸ì ïðåðûâàíèÿ ôóíêöèè sleep(30) ñèãíàëîì.

Ïðîáëåìó âûÿâëåíî íà äèñòðèáóòèâàé:

• SuSE 10 (64)
• Mandriva 2006
• FedoreCore4 (64)

Íà âñåõ ýòèõ äèñòðèáóòèâàõ èñïîëüçóåòñÿ: kernel >=2.6.12, glibc 2.3.5, gcc 4.0, NPTL

Íå âûÿâëåíî íà äèñòðèáóòèâàõ:

• ALM2.4
• ALC3.0
• ASPLinux 9

Ïîõîæå íà ïðîáëåìó â îñîáåííîñòè ðåàëèçàöèè èíòåðâàëüíîãî òàéìåðà íà NPTL.  ñâÿçè ñ êîòîðîé ñòàíîâèòñÿ íåâîçìîæíûì ïîëó÷èòü èíòåðâàëû â ïîòîêàõ äëÿ çàäà÷ òàêîãî òèïà.  ñâÿçè ñ ýòèì, äëÿ äàííûõ çàäà÷, ðàññìàòðèâàåòñÿ âàðèàíò èñïîëüçîâàíèÿ âîçìîæíîñòè òàéìåðà ñîçäàâàòü ïîòîê ïî èñòå÷åíèþ âðåìåíè.

Èñõîäíèêè òåñòîâîé ïðîãðàììû

#include <error.h> #include <stdio.h> #include <signal.h> #include <sys/time.h> #include <unistd.h> #include <stdlib.h> #include <pthread.h> void sighandler( int signal ) { printf("Signal test: %d.\n",signal); } void *Task(void *) { int sig; sigset_t set; timer_t tmId; struct itimerspec itval; struct sigevent sigev; sigemptyset(&set); sigaddset(&set, SIGUSR1); sigev.sigev_notify = SIGEV_SIGNAL; sigev.sigev_signo = SIGUSR1; itval.it_interval.tv_sec = 0; itval.it_interval.tv_nsec = 900000000; itval.it_value.tv_sec = 0; itval.it_value.tv_nsec = 900000000; int res = timer_create(CLOCK_REALTIME,&sigev,&tmId); if( res ) error(0, res, "timer_create"); else { res = timer_settime(tmId, 0, &itval, NULL); if( res ) error(0, res, "timer_settime"); } while( true ) { printf("Pthread inteval timer test.\n"); sigwait(&set, &sig); //pause(); } } int main() { pthread_t pthr_tsk; signal(SIGUSR1,sighandler); //signal(SIGALRM,sighandler); //Make process task pthread_attr_t pthr_attr; pthread_attr_init(&pthr_attr); pthread_attr_setschedpolicy(&pthr_attr,SCHED_OTHER); pthread_create(&pthr_tsk,&pthr_attr,Task,NULL); pthread_attr_destroy(&pthr_attr); while(true) { sleep(30); printf("Exit from programm!\n"); } pthread_kill(pthr_tsk, SIGUSR1); pthread_join(pthr_tsk, NULL); return 0; }