KITFORMA · EDITORIAL ANSWER
Why does every Python log line appear twice?
KitForma editorial guide. A logger may have its own handler while also propagating the same record to a parent handler. Repeated configuration can add duplicate handlers too.
Step-by-step answer
A logger may have its own handler while also propagating the same record to a parent handler. Repeated configuration can add duplicate handlers too.
Inspect handlers and propagation on the named logger and root logger. Configure output once at the application boundary; libraries should obtain a named logger without installing global output handlers. Test repeated imports and application initialization, not just one clean run. Set
propagate=False only when that logger intentionally owns its complete output path. Removing handlers indiscriminately can silence unrelated application logs, so fix the specific ownership issue rather than clearing the whole logging tree.Sources and verification
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