Log files should not be closed until their successor is open.
From #1042 (closed) as requested by @ondrej :
Identifying and debugging this would be much simpler if named ensured that all errors are logged by changing logging such that a log file isn't closed until its successor is open (assuming my guess is correct). This would guarantee that a failure to open gets logged in the previous logfile, which could continue to log. I have verified that the current logging code closes files before opening a successor
The quote is 11 months old - I haven't re-verified the observation in current code as I'm seriously underwater at the moment.