After installing or upgrading to Syslog-ng PE 7.0.21 the following internal log messages are seen:"Destination timeout has elapsed, closing connection"
The messages are informational.
In the case of destination files or network connections, Syslog-ng will not keep them open indefinitely. If no logs are written to a certain destination for a certain amount of time, Syslog-ng will close its file descriptor to that file.
This is done to keep the number of open files and sockets at bay. If new logs arrive, and need to be written to the already closed file or connection, Syslog-ng will automatically re-open it or reconnect.
This message is only informational and can be ignored.
The above being said the messages should only be seen at the verbose debug logging level and and not at the notice level.
Change request SYSLOGDEV-5505 has been raised so that the messages will only be seen in verbose logging. This fix will be in a future release of Syslog-ng PE.