python-gmp 0.5.3

Safe bindings to the GNU GMP library

Python extension module, providing bindings to the GNU GMP via the ZZ library (version 0.8.0 or later required). This module shouldn’t crash the interpreter.

The gmp can be used as a gmpy2/python-flint replacement to provide integer type (mpz), compatible with Python’s int. It also includes functions, compatible with the Python stdlib’s submodule math.integer.

This module requires Python 3.11 or later versions and has been tested with CPython 3.11 through 3.15, with PyPy3.11 7.3.23 and with GraalPy 25.0.3. Free-threading builds of the CPython are supported.

Releases are available in the Python Package Index (PyPI) at https://pypi.org/project/python-gmp/.

Motivation

The CPython (and most other Python implementations, like PyPy) is optimized to work with small (machine-sized) integers. Algorithms used here for big integers usually aren’t best known in the field. Fortunately, it’s possible to use bindings (for example, the gmpy2 package) to the GNU GMP, which aims to be faster than any other bignum library for all operand sizes.

But such extension modules usually rely on default GMP’s memory management and can’t recover from allocation failure. So, it’s easy to crash the Python interpreter during the interactive session. Following example with the gmpy2 will work if you set address space limit for the Python interpreter (e.g. by prlimit command on Linux):

>>> import gmpy2
>>> gmpy2.__version__
'2.2.1'
>>> z = gmpy2.mpz(29925959575501)
>>> while True:  # this loop will crash interpter
...     z = z*z
...
GNU MP: Cannot allocate memory (size=46956584)
Aborted

The gmp module handles such errors correctly:

>>> import gmp
>>> z = gmp.mpz(29925959575501)
>>> while True:
...     z = z*z
...
Traceback (most recent call last):
  File "<python-input-3>", line 2, in <module>
    z = z*z
        ~^~
MemoryError
>>> # interpreter still works, all variables in
>>> # the current scope are available,
>>> z.bit_length()  # including pre-failure value of z
93882077

Warning on –disable-alloca configure option

You should use the GNU GMP library, compiled with the ‘–disable-alloca’ configure option to prevent using alloca() for temporary workspace allocation, or this module may crash the interpreter in case of a stack overflow.