zmq_poll returns -1 ( Context has been shut down) when polling 2 sockets

Question

i am using zactor and in the call back i receive a pipe socket. i create a router socket and polling this sockets for messages. it is not working and giving -1 result as return value of zmq_poll; what could be the problem?

`void
echo_actor (zsock_t *pipe, void *args)
{
    // need to implement...?  
    printf("thread id : %lu", GetCurrentThreadId());
    server_t* self = server_new(pipe);
    zmq_pollitem_t items[] =
    {
        { self->pipe, 0, ZMQ_POLLIN, 0 },
        { self->router, 0, ZMQ_POLLIN, 0 }
    };
    self->monitor_at = zclock_time() + self->monitor;
    while (!self->stopped && !zctx_interrupted)
    {
        //  Calculate tickless timer, up to interval seconds
        uint64_t tickless = zclock_time() + self->monitor;        
        uint64_t diff = (tickless - zclock_time()) * ZMQ_POLL_MSEC;
        //  Poll until at most next timer event
        int rc = zmq_poll(items, 2, diff );
        if (rc == -1)
        {
            break;              //  Context has been shut down
        }            

        //  Process incoming message from either socket
        if (items[0].revents & ZMQ_POLLIN)
            server_control_message(self);

        if (items[1].revents & ZMQ_POLLIN)
            server_client_message(self);      

        //  If clock went past timeout, then monitor server
        if (zclock_time() >= self->monitor_at)
        {          
            printf("clock went past timeout, need to monitor the server");
        }
    }
    server_destroy(&self);
}`

int main()
{
    zactor_t *actor = zactor_new (echo_actor, "Hello, World");
    assert (actor);
    zstr_sendx (actor, "ECHO", "This is a string", NULL);    
    char *string = zstr_recv (actor);
    fprintf(stdout,"%s\n",string);
    assert (streq (string, "This is a string"));
    free (string);
    zactor_destroy (&actor);
}

pipe socket and router socket shall work with poll option, do not know how it is going wrong