code: @Override
      protected void channelSelectorClose() {
          synchronized (wqm.shutdownSync) {
              try {
                  selector.close();
              } catch (IOException e) {
                  // No FFDC code or exception handling needed since we are shutting down
              }
              // mark this channel's CS index as inactive.
              // This index will now available for a new CS entry.
              wqm.updateCount(countIndex, WorkQueueManager.CS_NULL, channelType);
          }
      }
docs: /*
  @see com.ibm.ws.tcpchannel.internal.ChannelSelector#channelSelectorClose()