pthread线程和信号

pthread线程和信号
所有的异步信号发到整个进程的所有线程（异步信号如kill, lwp_kill, sigsend, kill等调用产生的都是，异步信号也称为中断），而且所有线程共享信号的处理行为（即sigaction的设置，对于同一信号的设置，某一线程的更改会影响到所有线程）。但每个线程可以有自己的mask来阻止信号的发送，所以可以通过线程对mask的设置来决定信号发送到哪个线程。

设置mask的函数为:

#include <signal.h>
int pthread_sigmask(int how, const sigset_t *restrict set, sigset_t *restrict oset);

1 2	#include <signal.h> int pthread_sigmask(int how, const sigset_t restrict set, sigset_t restrict oset);

此外，线程可以通过sleep（超过指定时间或调用的进程/线程捕捉到某个信号并从信号处理程序返回时，sleep返回）或者sigwait来等待一个或多个信号发生。

#include <signal.h>
int pthread_sigwait(const sigset_t *restrict set, int *restrict signop);

1 2	#include <signal.h> int pthread_sigwait(const sigset_t restrict set, int restrict signop);

给进程发送信号可以调用kill，同样给线程调用信号可以使用pthread_kill

#include <signal.h>
int pthread_kill(pthread_t thread, int signo);

1 2	#include <signal.h> int pthread_kill(pthread_t thread, int signo);

可以发送一个0的signo来检查线程是否存在，如果信号的默认行为是终止进程(例如SIGARLM)，那么把该信号发送给某个线程会杀掉整个进程的所有线程。
另外注意ALARM是进程资源，并且所有线程共享相同的ALARM，设置一个alarm()会发送SIGARLM信号给所有线程,所以他们不可能互补干扰的使用alarm()。

here comes an example:

/*threadsig.c*/ 
#include <signal.h> 
#include <pthread.h> 
#include <stdio.h> 
 
void sighandler(int signo); 
 
void * 
thr1_fn(void *arg) 
{ 
    pthread_t   tid = pthread_self(); 
    int     rc; 
 
    printf("thread 1 with tid:%un", tid); 
    rc = sleep(60); 
    if (rc != 0) 
        printf("thread 1... interrupted at %d secondn", 60 - rc); 
    printf("thread 1 endsn"); 
    return NULL; 
} 
 
void * 
thr2_fn(void *arg) 
{ 
    struct sigaction    action; 
    pthread_t       tid = pthread_self();   
    int         rc, err;   
   
    printf("thread 2 with tid:%un", tid);   
     
    action.sa_flags = 0; 
    action.sa_handler = sighandler; 
       
    err = sigaction(SIGALRM, &action, NULL); 
     
    rc = sleep(60); 
    if (rc != 0) 
        printf("thread 2... interrupted at %d secondn", 60 - rc); 
    printf("thread 2 endsn"); 
    return NULL; 
} 
 
void * 
thr3_fn(void *arg) 
{ 
    pthread_t   tid = pthread_self();   
    sigset_t    mask;   
    int     rc, err;   
   
    printf("thread 3 with tid%un", tid); 
 
     
    sigemptyset(&mask); /* 初始化mask信号集 */   
   
    sigaddset(&mask, SIGALRM);   
    err = pthread_sigmask(SIG_BLOCK, &mask, NULL);   
    if (err != 0)   
    {   
        printf("%d, %s/n", rc, strerror(rc));   
        return NULL;   
    } 
   
    rc = sleep(60); 
        if (rc != 0) 
                printf("thread 3... interrupted at %d secondn", 60 - rc); 
        printf("thread 3 endsn"); 
        return NULL; 
 
    return NULL; 
} 
 
int 
main(void) 
{ 
    int     rc, err;   
    pthread_t   thr1, thr2, thr3, thrm = pthread_self(); 
 
    printf("thread main with pid %un", (unsigned int)thrm); 
    err = pthread_create(&thr1, NULL, thr1_fn, NULL); 
    if (err != 0) { 
        printf("error in creating pthread:%dt%sn",err, strerror(rc)); 
        exit(1); 
    } 
 
     
/*  pthread_kill(thr1, SIGALRM);    send a SIGARLM signal to thr1 before thr2 set the signal handler, then the whole process will be terminated*/ 
    err = pthread_create(&thr2, NULL, thr2_fn, NULL); 
    if (err != 0) { 
        printf("error in creating pthread:%dt%sn",err, strerror(rc)); 
        exit(1); 
    } 
     
    err = pthread_create(&thr3, NULL, thr3_fn, NULL); 
    if (err != 0) { 
        printf("error in creating pthread:%dt%sn",err, strerror(rc)); 
        exit(1); 
    } 
 
    sleep(3); 
    pthread_kill(thr1, SIGALRM); 
    pthread_kill(thr2, SIGALRM); 
    pthread_kill(thr3, SIGALRM); 
    pthread_join(thr1, NULL);   /*wait for the threads to complete.*/ 
    pthread_join(thr2, NULL); 
    pthread_join(thr3, NULL); 
    printf("main endsn"); 
    return 0; 
} 
 
void  
sighandler(int signo) 
{ 
    pthread_t   tid = pthread_self(); 
     
    printf("thread with pid:%u receive signo:%dn", tid, signo); 
    return; 
}

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/*threadsig.c*/

#include <signal.h>

#include <pthread.h>

#include <stdio.h>

void sighandler(int signo);

void *

thr1_fn(void *arg)

{

pthread_t tid = pthread_self();

int rc;

printf("thread 1 with tid:%un", tid);

rc = sleep(60);

if (rc != 0)

printf("thread 1... interrupted at %d secondn", 60 - rc);

printf("thread 1 endsn");

return NULL;

}

void *

thr2_fn(void *arg)

{

struct sigaction action;

pthread_t tid = pthread_self();

int rc, err;

printf("thread 2 with tid:%un", tid);

action.sa_flags = 0;

action.sa_handler = sighandler;

err = sigaction(SIGALRM, &action, NULL);

rc = sleep(60);

if (rc != 0)

printf("thread 2... interrupted at %d secondn", 60 - rc);

printf("thread 2 endsn");

return NULL;

}

void *

thr3_fn(void *arg)

{

pthread_t tid = pthread_self();

sigset_t mask;

int rc, err;

printf("thread 3 with tid%un", tid);

sigemptyset(&mask); /* 初始化mask信号集 */

sigaddset(&mask, SIGALRM);

err = pthread_sigmask(SIG_BLOCK, &mask, NULL);

if (err != 0)

{

printf("%d, %s/n", rc, strerror(rc));

return NULL;

}

rc = sleep(60);

if (rc != 0)

printf("thread 3... interrupted at %d secondn", 60 - rc);

printf("thread 3 endsn");

return NULL;

}

int

main(void)

{

int rc, err;

pthread_t thr1, thr2, thr3, thrm = pthread_self();

printf("thread main with pid %un", (unsigned int)thrm);

err = pthread_create(&thr1, NULL, thr1_fn, NULL);

if (err != 0) {

printf("error in creating pthread:%dt%sn",err, strerror(rc));

exit(1);

}

/* pthread_kill(thr1, SIGALRM); send a SIGARLM signal to thr1 before thr2 set the signal handler, then the whole process will be terminated*/

err = pthread_create(&thr2, NULL, thr2_fn, NULL);

if (err != 0) {

printf("error in creating pthread:%dt%sn",err, strerror(rc));

exit(1);

}

err = pthread_create(&thr3, NULL, thr3_fn, NULL);

if (err != 0) {

printf("error in creating pthread:%dt%sn",err, strerror(rc));

exit(1);

}

sleep(3);

pthread_kill(thr1, SIGALRM);

pthread_kill(thr2, SIGALRM);

pthread_kill(thr3, SIGALRM);

pthread_join(thr1, NULL); /*wait for the threads to complete.*/

pthread_join(thr2, NULL);

pthread_join(thr3, NULL);

printf("main endsn");

return 0;

}

void

sighandler(int signo)

{

pthread_t tid = pthread_self();

printf("thread with pid:%u receive signo:%dn", tid, signo);

return;

}

luffy@luffy-laptop:~/workspace/myapue$ ./threadsig
thread main with pid 3557979936
thread 1 with tid:3549923072
thread 2 with tid:3541530368
thread 3 with tid3533137664
thread with pid:3549923072 receive signo:14
thread with pid:3541530368 receive signo:14
thread 2… interrupted at 3 second
thread 1… interrupted at 3 second
thread 1 ends
thread 2 ends #then wait for 27 seconds and thread-3 ends
thread 3 ends
main ends

thr2设置的信号处理程序sighandler也应用到其他线程，thr3由于设置mask所有阻塞了SIGARLM信号。

Reference:
APUE
线程信号 http://blog.csdn.net/copal/article/details/5454279

pthread线程和信号

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