there is a problem with closing the channel then the
 method throws an IOException and the exception contains reasons for the
 failure.
 <p>
 If an attempt is made to perform an operation on a closed channel then a
 <code><a href="../../../../reference/java/nio/channels/ClosedChannelException.html">ClosedChannelException</a></code> will be thrown on that attempt.
 <p>
 If multiple threads attempt to simultaneously close a channel, then only
 one thread will run the closure code, and others will be blocked u