python - 为什么python dict键的顺序不一致？

Question

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Answer 1

此行为在 object.__hash__() 中有详细说明的规范；这是为了防止某些类型的恶意输入破坏应用程序:

Note By default, the __hash__() values of str, bytes and datetime objects are “salted” with an unpredictable random value. Although they remain constant within an individual Python process, they are not predictable between repeated invocations of Python.

This is intended to provide protection against a denial-of-service caused by carefully-chosen inputs that exploit the worst case performance of a dict insertion, O(n^2) complexity. See http://www.ocert.org/advisories/ocert-2011-003.html for details.

在 Python 3.3 之前，情况并非如此，字典将在同一应用程序的不同运行之间具有相同的顺序。

我回答了一个related question关于禁用此行为，它链接到一些相关的源代码。