code: public void shutdown() {
  		synchronized (lock) {
  			if (isShutdown) {
  				return;
  			}
  
  			LOG.info("Shutting down the network environment and its components.");
  
  			// terminate all network connections
  			try {
  				LOG.debug("Shutting down network connection manager");
  				connectionManager.shutdown();
  			}
  			catch (Throwable t) {
  				LOG.warn("Cannot shut down the network connection manager.", t);
  			}
  
  			// shutdown all intermediate results
  			try {
  				LOG.debug("Shutting down intermediate result partition manager");
  				resultPartitionManager.shutdown();
  			}
  			catch (Throwable t) {
  				LOG.warn("Cannot shut down the result partition manager.", t);
  			}
  
  			// make sure that the global buffer pool re-acquires all buffers
  			networkBufferPool.destroyAllBufferPools();
  
  			// destroy the buffer pool
  			try {
  				networkBufferPool.destroy();
  			}
  			catch (Throwable t) {
  				LOG.warn("Network buffer pool did not shut down properly.", t);
  			}
  
  			isShutdown = true;
  		}
  	}
docs: Tries to shut down all network I/O components.