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gh-153568: Use a managed dict for AST nodes - #160616
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AST nodes had an explicit `__dict__`` slot, so every node built by `ast.parse` allocated its own dict. With Py_TPFLAGS_MANAGED_DICT, node attributes are stored as inline values with shared keys instead. `ast.parse` is ~15.8% faster, walking trees is ~15.9% faster, and the memory used by the AST trees is reduced by ~51.6%.
lysnikolaou
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tomasr8
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October 24, 2026 19:00
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AST nodes had an explicit
__dict__slot, so every node built byast.parseallocated its own dict. WithPy_TPFLAGS_MANAGED_DICT, node attributes are stored as inline values with shared keys instead.ast.parseis ~15.8% faster, walking trees is ~15.9% faster, and the memory used by the AST trees is reduced by ~51.6%.