code: public void performOptimizedRead(byte[] handle, long length, int blocksize,
  			java.io.OutputStream out, int outstandingRequests,
  			FileTransferProgress progress) throws SftpStatusException,
  			SshException, TransferCancelledException {
  
  		performOptimizedRead(handle, length, blocksize, out,
  				outstandingRequests, progress, 0);
  	}
docs: Performs an optimized read of a file through use of asynchronous
  messages. The total number of outstanding read requests is configurable.
  This should be safe on file objects as the SSH protocol states that file
  read operations should return the exact number of bytes requested in each
  request. However the server is not required to return the exact number of
  bytes on device files and so this method should not be used for device
  files.
  
  @param handle
  the open files handle
  @param length
  the length of the file
  @param blocksize
  the blocksize to read
  @param out
  an OutputStream to output the file into
  @param outstandingRequests
  the maximum number of read requests to
  @param progress
  @throws SshException