...

• If operating system does not support zero copy, sending a file with FileChannel#transferTo might fail or yield worse performance.
  For example, sending a large file doesn't work well enough on Windows;
• The ssl SSL must be disabled to take an advantage of JAVA NIO zero copy file transmission by using FileChannel#transferTo. We can consider to use OpenSSL's non-copying interface to avoid allocating new buffers for each read and write operation at Phase-2;

Discussion Links

// Links to discussions on the devlist, if applicable.

...