requirements.txt

click
redis

transactions.py

#!/usr/bin/env python
import click
import functools
import signal
import uuid
from multiprocessing import Pool


def run(keys, iterations, retry_failures):
    from redis import (
        StrictRedis,
        WatchError,
    )

    result = [0, 0]

    def increment():
        """Update counters."""
        with client.pipeline(transaction=True) as transaction:
            transaction.watch(*keys)
            counts = transaction.mget(keys)
            try:
                transaction.multi()
                updates = {}
                for key, count in zip(keys, counts):
                    updates[key] = (int(count) if count is not None else 0) + 1
                transaction.mset(updates)
                transaction.execute()
            except WatchError:
                result[1] += 1
                if retry_failures:
                    increment()
            else:
                result[0] += 1

    try:
        client = StrictRedis()
        for i in xrange(iterations):
            increment()
    except KeyboardInterrupt:
        pass

    return result


@click.command()
@click.option('-c', '--concurrency', default=4)
@click.option('-n', '--num-keys', default=2)
@click.option('-i', '--iterations', default=500)
@click.option('--retry-failures', default=False, is_flag=True)
def __main__(concurrency, num_keys, iterations, retry_failures):
    namespace = uuid.uuid1().hex
    keys = ['{}:{}'.format(namespace, i) for i in xrange(num_keys)]

    pool = Pool(concurrency)

    results = []
    for _ in xrange(concurrency):
        results.append(pool.apply_async(run, (keys, iterations, retry_failures)))

    signal.signal(signal.SIGINT, signal.SIG_IGN)

    successes = 0
    failures = 0

    for result in results:
        data = result.get()
        successes += data[0]
        failures += data[1]

    stdout = click.get_text_stream('stdout')
    stdout.write(
        '{} {} {:%}\n'.format(
            successes,
            failures,
            float(successes) / (successes + failures)
        )
    )


if __name__ == '__main__':
    __main__()