有时向pthread注入运行时异常失败。怎么解决?

我尝试使用信号将异常注入到线程中,但有时无法捕获异常。例如,以下代码:

void _sigthrow(int sig)
{
    throw runtime_error(strsignal(sig));
}
struct sigaction sigthrow = {{&_sigthrow}};

void* thread1(void*)
{
    sigaction(SIGINT,&sigthrow,NULL);
    try
    {
        while(1) usleep(1);
    }
    catch(exception &e)
    {
        cerr << "Thread1 catched " << e.what() << endl;
    }
};

void* thread2(void*)
{
    sigaction(SIGINT,&sigthrow,NULL);
    try
    {
        while(1);
    }
    catch(exception &e)
    {
        cerr << "Thread2 catched " << e.what() << endl; //never goes here
    }
};

如果我试着像这样执行:

int main()
{
    pthread_t p1,p2;

    pthread_create( &p1, NULL, &thread1, NULL );
    pthread_create( &p2, NULL, &thread2, NULL );

    sleep(1);

    pthread_kill( p1, SIGINT);
    pthread_kill( p2, SIGINT);

    sleep(1);

    return EXIT_SUCCESS;
}

我得到以下输出:

Thread1 catched Interrupt
terminate called after throwing an instance of 'std::runtime_error'
  what():  Interrupt
Aborted

如何使第二个威胁捕获异常? 有没有更好的方法来注入异常?