broken.py

"""
Broken example.
"""
from cassandra.cluster import Cluster
from multiprocessing import Pool

size = 4

keyspace = 'system'

def executor(i):
    cluster = Cluster()
    session = cluster.connect(keyspace)
    return list(map(list, session.execute('select * from schema_keyspaces;')))


if __name__ == '__main__':
    pool = Pool(size)
    for result in pool.imap_unordered(executor, xrange(0, size)):
        print result

working.py

"""
Working example.
"""
from multiprocessing import Pool

size = 4

keyspace = 'system'

def executor(i):
    from cassandra.cluster import Cluster
    cluster = Cluster()
    session = cluster.connect(keyspace)
    return list(map(list, session.execute('select * from schema_keyspaces;')))


if __name__ == '__main__':
    pool = Pool(size)
    for result in pool.imap_unordered(executor, xrange(0, size)):
        print result