When Does Python Allocate Memory for Identical Strings?

Python Memory Allocation for Identical Strings

Background:

In Python, string objects with identical characters may occupy the same memory space (id(a) == id(b)) or reside in separate locations (id(a) != id(b)). This allocation behavior varies depending on factors such as the creation method and context.

String Creation and Allocation:

When a string literal ("abc") is defined within a function, all occurrences of that literal within that function typically share the same memory space. This is because the interpreter recognizes the literal during function compilation and optimizes its storage.

However, when strings are created across different functions, or when they are built dynamically (e.g., "a" "b"), the memory allocation behavior becomes less predictable.

File Input and Memory Allocation:

When a list of strings is created from a file and subsequently read back into memory, each string may be stored in a separate memory location. This is because the file operations involve creating new string objects, and the interpreter does not attempt to find and reuse existing ones.

Understanding Python String Memory Allocation:

Python implementations balance the trade-off between memory usage and allocation speed. When locating and sharing existing objects is efficient (e.g., within a single function), it is typically done to save memory. However, when it may be time-consuming to locate identical objects across multiple scopes or contexts, the interpreter creates new objects.

Historical Footnote:

Some languages, such as SPITBOL, pioneered the technique of uniquifying all strings to conserve memory. While this approach has its benefits, Python's current implementation does not employ such a strategy.

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