File input on Windows prevents log rolling because the handle is locked

The file input keeps the file open between reads, which causes the handle to be locked on Windows. This prevents renaming or deleting of the file, which prevents file rotation. A mitigation is to patch the filewatch gem to close the file between each read cycle, which reduces the locking window. The correct fix would be to open the file in read-only / shared mode, which doesn't seem to be a concept available in ruby.

See also: LOGSTASH-394, which is the same unresolved issue...