How does Python allocate memory? Tell me about arenas, pools, and blocks.

Python uses its own memory management system, which includes several levels:

• Arena:

  • This is a large block of memory, usually about 256 KB, allocated from the operating system.
  • The Arena is divided into smaller parts — pools.

• Pool:

  • A pool is a block of memory of size 4 KB that contains several blocks of the same size.
  • Pools are organized by size classes (e.g., 8, 16, 32 bytes, etc.) to efficiently manage objects of different sizes.

• Block:

  • This is the smallest unit of memory allocation for Python objects.
  • Each block contains one object.

Working mechanism:

1. When creating a Python object, a block of the required size is allocated from the corresponding pool.
2. If the pool is full, a new pool is allocated from the arena.
3. If the arena is full, a new arena is allocated from the OS.

This multi-level approach allows efficient memory management, reduces fragmentation, and speeds up object allocation and deallocation.

Additionally, Python uses a garbage collector to clean up cyclic references and counts references to manage object lifetimes.