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Speed up logging.getLogger() for already-registered loggers #150818
Description
logging.getLogger(name) returns the singleton logger for a name, creating it on first use. Every call takes the logging lock, even the overwhelmingly common case where the logger already exists and is returned unchanged.
Libraries fetch their logger by name throughout their code — at module import and often again inside functions — so the same handful of names are looked up over and over for the lifetime of a process. These repeat lookups are pure overhead: the logger is already there.
Resolving logger names collected from the top-1000 corpus takes 6.68 µs today and 5.02 µs with a lock-free fast path for the already-registered case, 33% faster. First-time creation, placeholder resolution and the parent/child wiring still run under the lock exactly as before, and the fast path relies only on an atomic dict lookup so it is safe under both the GIL and free threading.
Linked PRs
- gh-150818: Speed up logging.getLogger() for existing loggers (GH-150825) #150825
- [3.13] gh-150818: Speed up logging.getLogger() for existing loggers (GH-150825) #150927
- [3.14] gh-150818: Speed up logging.getLogger() for existing loggers (GH-150825) #150928
- [3.15] gh-150818: Speed up logging.getLogger() for existing loggers (GH-150825) #150929
- gh-150818: Wire logger parent before publishing it in getLogger() (GH-150941) #150941
Activity
pythongh-150818: Speed up logging.getLogger() for existing loggers
pythongh-150818: Speed up logging.getLogger() for existing loggers
gh-150818: Speed up logging.getLogger() for existing loggers (GH-150825)
merwok commented on Jun 5, 2026
Surprised to read this! I am familiar with the module-level instantiation idiom.
pythongh-150818: Skip new test where threading is unavailable
gh-150818: Wire logger parent before publishing it in getLogger() (GH…
pythongh-150818: Speed up logging.getLogger() for existing loggers (p…
pythongh-150818: Wire logger parent before publishing it in getLogger…