[Discuss-gnuradio] CANNOT shutdown usrp with destructor

[zzw.1012]

 Hi,

    I am studying GNURadio now. but I have a problem with it. At first, there is a test file called test_usrp_standard_tx.cc. This file is work well and usrp can be shutdown automatically when all my wanted data are transmitted. then, I add a code like followed:

//test_usrp_standard_tx.cc

...

utx->start();

test_output(utx, (long long)nsamples, amp, waveform);

while(1); // added code

return 0;

}

As result of Spectrum Analyzer, it always have  frequency spectrum even though I pull out usrp's USB wire. So, I  think the action of shutdown usrp is occured in destructor.

However, when I test my own code, it cannot shutdown usrp too. here is my new test code:

 

gr_message_source_sptr x0 = gr_make_message_source(1, 4);
gr_top_block_sptr tb = gr_make_top_block("topblock");

void* msg_source_proc (void *args)
{

        ...
        gr_message_sptr msg = gr_make_message_from_string(s, 0, 0, 0);
        x0->msgq()->insert_tail(msg);

        return NULL;
}

main()

{       pthread_t thd_src;
        pthread_attr_t  attr;

        pthread_attr_init(&attr);
        pthread_create(&thd_src, &attr, msg_source_proc, NULL);

        ...

        usrp_sink_c_sptr x6 = usrp_make_sink_c(which_board, interp_rate, nchan, -1, 0, 0);

        usrp_subdev_spec subdev_spec = x6->pick_tx_subdevice();

        db_base_sptr db = x6->selected_subdev(subdev_spec);

        ....

        usrp_tune_result r;

        x6->tune(db->which(), db, center_freq, &r);

        db->set_enable(true);

        tb->connect(x0,0,x1,0);//connect blocks
        tb->connect(x1,0,x2,0);
        tb->connect(x2,0,x3,0);
        tb->connect(x3,0,x4,0);
        tb->connect(x4,0,x5,0);
        tb->connect(x5,0,x6,0);

        tb->run();

        printf ("*******************\n");

        return 0;
}

    The result showned that it can send a pkt well but cannot shutdown usrp and  "printf ("*******************\n")" have not print;

    So I think the program doesn't jump out of "tb->run" . to say nothing of destsructor which is to shutdown usrp.

    what's wrong with this? I need you help.

    thank you very much

    best wishes!