#include <signal.h>
#include <stdio.h>
#include <time.h>
#include <unistd.h>
void handler(int signum)
{
char result[100];
time_t now;
// struct tm time1;
now = time(NULL);
// localtime_r(&now, &time1);
// ctime_r(&now,result);
strcpy(result,ctime(&now));
// strftime(result, 100, "%T", &time1);
printf("At %s, user pressed Ctrl-C\n", result);
}
int main (void)
{
time_t now;
// struct tm ltime;
char result[100];
if (signal(SIGINT, handler) == SIG_IGN)
signal(SIGINT, SIG_IGN);
now = time(NULL);
while(1) {
#ifdef UNSAFE
// localtime_r(&now, <ime);
ctime(&now);
#endif
}
return 0;
}
對於信號處理函數,儘量做到簡單,如果調用了不可重入函數,可能引發死鎖問題。
#16 0x0000003257e7230f in _int_free () from /lib64/libc.so.6
#17 0x0000003257e7276b in free () from /lib64/libc.so.6
#18 0x0000003257e8c7ca in tzset_internal () from /lib64/libc.so.6
#19 0x0000003257e8cf2e in __tz_convert () from /lib64/libc.so.6
#20 0x0000003257e8b529 in ctime () from /lib64/libc.so.6
strace -p 1202 Process 1202 attached - interrupt to quit futex(0x3258154fc0, FUTEX_WAIT_PRIVATE, 5, NULL
gcc -D UNSAFE test1.c -o test_unsafe
gcc -D UNSAFE test1.c -o test
編譯上面這個程序可以重現這個問題。
線程中也不要調用非線程安全系統調用,否則也會出現死鎖。
關於futex的文章
http://www.cnblogs.com/yysblog/archive/2012/11/03/2752728.html