title: When and why PARTIAL_WAKE_LOCK is required?
body: <p>All other wake locks makes sense e.g. developer want screen not to go off while performing something. But in partial wake lock <a href="http://developer.android.com/reference/android/os/PowerManager.html#PARTIAL_WAKE_LOCK" rel="nofollow">documentation</a> says that :</p>
  
  <blockquote>
    <p>If you hold a partial wake lock, the CPU will continue to run,
    regardless of any display timeouts or the state of the screen and even
    after the user presses the power button. In all other wake locks, the
    CPU will run, but the user can still put the device to sleep using the
    power button.</p>
  </blockquote>
  
  <p>Does that mean while performing some operation CPU can go off? Is it required to acquire wake lock in a service?</p>