Python 3.15: Lazy Imports, Frozendict, and a Faster JIT
Python 3.15 release candidate: explicit lazy imports, the new frozendict and sentinel types, the Tachyon profiler, and real JIT benchmark numbers.
CPython, the reference Python implementation: new releases, PEPs, JIT, WebAssembly and internals.
Python 3.15 release candidate: explicit lazy imports, the new frozendict and sentinel types, the Tachyon profiler, and real JIT benchmark numbers.
Python 3.15 ships a built-in frozendict — hashable, O(1) lookups, order-preserving, thread-safe by design. Here's the full technical picture: the 14-year history, how hashing works, what it unlocks for lru_cache and free-threaded Python, and every sharp edge you need to know before you use it.
CPython has had informal WebAssembly support since Python 3.11. PEP 816 changes that. Brett Cannon just locked down exactly which WASI and SDK versions each Python release will target — and why SDK versions 26 and 27 got blacklisted entirely.
Python runs Instagram, Dropbox, Netflix, Spotify, and Reddit. It trains the models that power modern AI. It processes petabytes of data in enterprise pipelines. And I ignored it for years because I thought it was just for academics. Here is what changed my mind.