Jul 27 16:16:09 LokalWiki wee_database[1320746] INFO __main__: Preparing to calculate missing derived observations...
Jul 27 16:16:09 LokalWiki wee_database[1320746] INFO __main__: Missing derived observations will be calculated from 2021-02-02 00:00:01 CET (1612220401) through to 2021-02-03 00:00:00 CET (1612306800) inclusive.
Jul 27 16:16:34 LokalWiki wee_database[1320746] DEBUG weewx.manager: Daily summary version is 4.0
Jul 27 16:16:34 LokalWiki wee_database[1320746] INFO __main__: Calculating missing derived observations...
Jul 27 16:16:34 LokalWiki wee_database[1320746] DEBUG weewx.engine: Loading service weewx.engine.StdTimeSynch
Jul 27 16:16:34 LokalWiki wee_database[1320746] DEBUG weewx.engine: Finished loading service weewx.engine.StdTimeSynch
Jul 27 16:16:34 LokalWiki wee_database[1320746] DEBUG weewx.engine: Loading service ...
Jul 27 16:16:39 LokalWiki wee_database[1320746] INFO weewx.wxservices: StdWXCalculate will use data binding wx_binding
Jul 27 16:16:39 LokalWiki wee_database[1320746] DEBUG weewx.manager: Daily summary version is 4.0
Jul 27 16:16:39 LokalWiki wee_database[1320746] message repeated 3 times: [ DEBUG weewx.manager: Daily summary version is 4.0]
Jul 27 16:16:39 LokalWiki wee_database[1320746] INFO weewx.wxxtypes: Type beaufort has been deprecated. Use unit beaufort instead.
Jul 27 16:16:39 LokalWiki wee_database[1320746] INFO weewx.manager: Starting backfill of daily summaries
Jul 27 16:16:40 LokalWiki wee_database[1320746] INFO weewx.manager: Processed 288 records to backfill 1 day summaries in 0.71 seconds
Jul 27 16:16:40 LokalWiki wee_database[1320746] INFO weecfg.database: Processed 1 day consisting of 288 records. 1 day consisting of 288 records were updated in 6.63 seconds.
Jul 27 16:16:40 LokalWiki wee_database[1320746] INFO __main__: Missing derived observations calculated in 6.64 seconds
...
Jul 27 16:18:53 LokalWiki wee_database[1320746] DEBUG urllib3.connectionpool: Starting new HTTPS connection (1): opendata.dwd.de:443
Jul 27 16:18:54 LokalWiki wee_database[1320746] DEBUG urllib3.connectionpool: https://opendata.dwd.de:443 "GET /weather/radar/composite/wn/WN_LATEST.tar.bz2 HTTP/1.1" 200 5501583
Jul 27 16:18:55 LokalWiki wee_database[1320746] INFO user.DWD.base: successfully downloaded https://opendata.dwd.de/weather/radar/composite/wn/WN_LATEST.tar.bz2 in 1.66 seconds
Jul 27 16:18:59 LokalWiki wee_database[1320746] DEBUG urllib3.connectionpool: Starting new HTTPS connection (1): opendata.dwd.de:443
Jul 27 16:18:59 LokalWiki wee_database[1320746] DEBUG urllib3.connectionpool: https://opendata.dwd.de:443 "GET /weather/text_forecasts/html/VHDL50_DWLG_LATEST_html HTTP/1.1" 200 609
Jul 27 16:18:59 LokalWiki wee_database[1320746] INFO user.DWD.base: successfully downloaded https://opendata.dwd.de/weather/text_forecasts/html/VHDL50_DWLG_LATEST_html in 0.11 seconds
Jul 27 16:18:59 LokalWiki wee_database[1320746] DEBUG urllib3.connectionpool: https://opendata.dwd.de:443 "GET /weather/text_forecasts/html/VHDL51_DWLG_LATEST_html HTTP/1.1" 200 478
Jul 27 16:18:59 LokalWiki wee_database[1320746] INFO user.DWD.base: successfully downloaded https://opendata.dwd.de/weather/text_forecasts/html/VHDL51_DWLG_LATEST_html in 0.03 seconds
Jul 27 16:18:59 LokalWiki wee_database[1320746] DEBUG urllib3.connectionpool: https://opendata.dwd.de:443 "GET /weather/text_forecasts/html/VHDL52_DWLG_LATEST_html HTTP/1.1" 200 340
Jul 27 16:18:59 LokalWiki wee_database[1320746] INFO user.DWD.base: successfully downloaded https://opendata.dwd.de/weather/text_forecasts/html/VHDL52_DWLG_LATEST_html in 0.04 seconds
Jul 27 16:18:59 LokalWiki wee_database[1320746] DEBUG urllib3.connectionpool: https://opendata.dwd.de:443 "GET /weather/text_forecasts/html/VHDL53_DWLG_LATEST_html HTTP/1.1" 200 270
Jul 27 16:18:59 LokalWiki wee_database[1320746] INFO user.DWD.base: successfully downloaded https://opendata.dwd.de/weather/text_forecasts/html/VHDL53_DWLG_LATEST_html in 0.06 seconds
Jul 27 16:18:59 LokalWiki wee_database[1320746] DEBUG urllib3.connectionpool: https://opendata.dwd.de:443 "GET /weather/text_forecasts/html/VHDL54_DWLG_LATEST_html HTTP/1.1" 200 516
Jul 27 16:18:59 LokalWiki wee_database[1320746] INFO user.DWD.base: successfully downloaded https://opendata.dwd.de/weather/text_forecasts/html/VHDL54_DWLG_LATEST_html in 0.11 seconds
The last lines about downloading are repeated every archive interval. They come from the weewx-DWD data service, which has the purpose of adding data to the archive record. So it is correct that they download files while WeeWX is running. But it is not necessary while calculating missing derived values. That would be no problem, if wee_database / weectl would call the shutDown() method at the end, as the service cares for shutting down the threads appropriately when this method is called, which weewxd does when shutting down.
The OP of the referenced thread can apply the fix to an his existing v5 install by downloading the fixed database.py