Merge pull request #4191 from garyzjq/jiaqz/inodestuck

in_tail: Check detaching inode when follow_inodes

lib/fluent/plugin/in_tail.rb

@@ -526,6 +526,10 @@ def update_watcher(tail_watcher, pe, new_inode)
     # so adding close_io argument to avoid this problem.
     # At shutdown, IOHandler's io will be released automatically after detached the event loop
     def detach_watcher(tw, ino, close_io = true)
+      if @follow_inodes && tw.ino != ino
+        log.warn("detach_watcher could be detaching an unexpected tail_watcher with a different ino.",
+                  path: tw.path, actual_ino_in_tw: tw.ino, expect_ino_to_close: ino)
+      end
       tw.watchers.each do |watcher|
         event_loop_detach(watcher)
       end