qtconcurrent dont close correctly

hi everybody, i want to create a unkillable process so i m using a mq pattern run in different thread like this

Code:

void UnkillApp::checkKeepServer()
{
    const char* recm = s_recv(socket);
    if(recm == NULL)
    {
        QProcess::startDetached(m_cpath);
    }
    else if(strcasecmp(recm, "kill") == 0)
    {
        s_send(socket, "kill");
 
        QProcess p;
        p.setProgram(m_cpath);
        p.kill();
    }
 
    s_send(socket, "keepalive");
}
 
void UnkillApp::checkKeepClient()
{
    int rc = s_send(socket, "areyoualive?");
 
    const char* recm = s_recv(socket);
    if(recm == NULL)
    {
        QProcess::startDetached(m_cpath);
    }
    else if(strcasecmp(recm, "kill") == 0)
    {
        s_send(socket, "kill");
        QProcess p;
        p.setProgram(m_cpath);
        p.kill();
    }
}
 
void UnkillApp::run()
{
    while (b_run) {
        if(b_server)
            checkKeepServer();
        else
            checkKeepClient();
 
        sleep(1);
    }
}
 
void UnkillApp::runInBackground()
{
    QtConcurrent::run(this, &UnkillApp::run);
}
 
void UnkillApp::closethread()
{
    b_run = false;
}

and this is the main function

Code:

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
 
    UnkillApp s("keepusA", true);
    s.runInBackground();
 
   // MainForm w;
    MainWindow w;
    w.show();
 
    QObject::connect(&w, SIGNAL(closed()), &s, SLOT(closethread()));
 
    return a.exec();
}

but after closing mainwindow in debug mode i can see b_run = false; called but application dont exit and i must kill it why? (and i dont run any other process yet)