5. Runtime Systems

Modules and imports, packages, the import lock, descriptors, classes and metaclasses, the MRO, the GIL, threads, subinterpreters, signals, context variables, and audit hooks.

12 items

Chapter Title
40 Modules and Imports
41 Packages
42 The Import Lock
43 Descriptors
44 Classes and Metaclasses
45 The MRO
46 The GIL
47 Threads
48 Subinterpreters
49 Signals
50 Context Variables
51 Audit Hooks
Deep Reads › CPython Internals › 5. Runtime Systems ›

40. Modules and Imports

The import machinery: finders, loaders, sys.modules cache, and the importlib bootstrap sequence.
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Deep Reads › CPython Internals › 5. Runtime Systems ›

41. Packages

Package __init__.py, namespace packages (PEP 420), relative imports, and __path__ manipulation.
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Deep Reads › CPython Internals › 5. Runtime Systems ›

42. The Import Lock

The per-module import lock, re-entrant import detection, and deadlock scenarios in multithreaded code.
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Deep Reads › CPython Internals › 5. Runtime Systems ›

43. Descriptors

__get__, __set__, __delete__ protocol, data vs. non-data descriptors, and property/classmethod/staticmethod internals.
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Deep Reads › CPython Internals › 5. Runtime Systems ›

44. Classes and Metaclasses

type.__new__ and type.__init__, __init_subclass__, __set_name__, and metaclass resolution order.
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Deep Reads › CPython Internals › 5. Runtime Systems ›

45. The MRO

C3 linearization algorithm, mro() computation, and how Python resolves method lookup across multiple inheritance.
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Deep Reads › CPython Internals › 5. Runtime Systems ›

46. The GIL

GIL purpose, implementation in Python/ceval_gil.c, forced release intervals, and its effect on multi-core performance.
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Deep Reads › CPython Internals › 5. Runtime Systems ›

47. Threads

Python thread objects, OS thread mapping, the GIL acquisition protocol, and thread-local state management.
cpython python internals runtime concurrency
Deep Reads › CPython Internals › 5. Runtime Systems ›

48. Subinterpreters

Per-interpreter state isolation, Py_NewInterpreterFromConfig, and the experimental per-interpreter GIL.
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Deep Reads › CPython Internals › 5. Runtime Systems ›

49. Signals

Signal handler registration, the eval breaker flag, and safe SIGINT delivery to Python code.
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Deep Reads › CPython Internals › 5. Runtime Systems ›

50. Context Variables

PEP 567 Context and ContextVar objects, context copying on task creation, and asyncio integration.
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Deep Reads › CPython Internals › 5. Runtime Systems ›

51. Audit Hooks

sys.addaudithook, the cpython.PyAudit_AddHook C API, and auditable events across the standard library.
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