rdflib hashing test

rdflib_hashing.py

from multiprocessing import Process, Manager, Lock
import random


def f(d):
    from rdflib import URIRef
    for i in random.sample(range(1000), 1000):
        k = URIRef('foo'+str(i))
        with l:
            if k not in d:
                d[k] = 0
            d[k] += 1

if __name__ == '__main__':
    manager = Manager()

    d = manager.dict()
    l = Lock()

    p1 = Process(target=f, args=(d,))
    p2 = Process(target=f, args=(d,))
    p1.start()
    p2.start()
    p1.join()
    p2.join()

    print d
    assert len(d) == 1000
    for v in d.values():
        assert v == 2

This was an attempt to provoke a bug with unstable hashing of URIRef as in RDFLib/rdflib#500 by using URIRefs as keys of a dict from multiple processes.

The idea was that as different processes invoking hash(URIRef('foo')) return different hashes that if they shared a dict this could lead to items ending in different buckets of the dict. It seems though as if manager.dict() doesn't get tricked by this...