Errno::ENOENT seen in Discoverer when a discovered file is immediately removed.

[guyboertje]

If a discovered file is removed before Discoverer has a created a WatchedFile for it then the WatchedFile creation step throws Errno::ENOENT.

[guyboertje]

This issue applies to version 4.1.0 and above.

Work around fix (not tested).
In file vendor/bundle/jruby/2.3.0/gems/logstash-input-file-4.1.X/lib/filewatch/discoverer.rb
replace the whole if .. end block starting at line 65 with:

        if watched_file.nil?
          begin
            path_stat = PathStatClass.new(pathname)
          rescue Errno::ENOENT
            next
          end
          watched_file = WatchedFile.new(pathname, path_stat, @settings)
          new_discovery = true
        end