Python extension module providing safe bindings to the GNU GMP. This module shouldn't crash the interpreter!
It can be used as a gmpy2/python-flint replacement to provide CPython-compatible integer (mpz) and rational (mpq) types. The module includes also few functions (factorial, gcd and isqrt), compatible with the stdlib's module math.
Most GMP packages enable using alloca() for temporary workspace allocation. This module can't prevent a crash in case of a stack overflow. To avoid this, you should compile the GMP library with '--disable-alloca' configure option to use rather the heap for all temporary allocations.
This extension customize memory allocation routines, used by the GMP. Don't use together with other GMP bindings, like the gmpy2!
The CPython (and most other Python implementations, like PyPy) is optimized to work with small integers. Algorithms used here for "big enough" integers usually aren't best known in the field. Fortunately, it's possible to use bindings (for example, the gmpy2 package) to the GNU Multiple Precision Arithmetic Library (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 allocation functions and can't recover from errors such as out of memory. So, it's easy to crash the Python interpreter during the interactive session. Following example with the gmpy2 should work on most Unix systems:
>>> import gmpy2, resource
>>> gmpy2.__version__
'2.2.1'
>>> resource.setrlimit(resource.RLIMIT_AS, (1024*32*1024, -1))
>>> z = gmpy2.mpz(29925959575501)
>>> while True: # this loop will crash interpter
... z = z*z
...
GNU MP: Cannot allocate memory (size=2949160)
AbortedThe gmp module handles such errors correctly:
>>> import gmp, resource
>>> resource.setrlimit(resource.RLIMIT_AS, (1024*32*1024, -1))
>>> 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
mpz(5867630)