Open Stack

Kevin Carter wrote:
>> I believe Clint already linked to
>> https://aphyr.com/posts/309-knossos-redis-and-linearizability or
>> similar - but 'known for general ease of use and reliability' is uhm,
>> a bold claim. Its worth comparing that (and the other redis writeups)
>> to this one: https://aphyr.com/posts/291-call-me-maybe-zookeeper. "Use
>> zookeeper, its mature".
> 
> Those write ups are from 2013 and with general improvements in Redis over the last two years I'd find it hard to believe that they're still relevant, however its worth testing to confirm if Redis is deemed as a viable option.
> 
>> The openjdk is present on the same linux distributions, and has been
>> used in both open source and proprietary programs for decades. *what*
>> license implications are you speaking of?
> 
> The license issues would be related to deployers using Oracle java which may or may not be needed by certain deployers for scale and performance requirements. While I do not have specific performance numbers at my fingertips to illustrate general performance issues using zookeeper at scale with OpenJDK, I have, in the past, compared OpenJDK to Oracle Java and found that Oracle java was quite a bit more stable and packed far more performance capabilities.   I did find [ http://blog.cloud-benchmarks.org/2015/07/17/cassandra-write-performance-on-gce-and-aws.html ] which claims a 32% performance improvement with casandra using Oracle Java 8 over OpenJDK on top of the fact that it was less prone to crashes but that may not be entirely relevant to this case. Also there's no denying that Oracle has a questionable history dealing with Opensource projects regarding Java in the past and because performance / stability concerns may require the use of Oracle Java which will undoubtedly
  come wit
h questionable license requirements.

I can't be suspected of JVM sympathies, and I find that a bit unfair.
I'll try to summarize:

1- ZooKeeper is a very good DLM

2- ZooKeeper is totally supported under OpenJDK and is run under this
configuration by large users (see Josh's other post for data)

3- /Some/ large Java stacks run faster / better under Oracle's non-free
JVM, but (1) there is no evidence that ZooKeeper is one of them and (2)
this is less and less true with modern JDKs (which are all built on top
of OpenJDK)

4- Still, some shops will prefer to stay out of Java stacks for various
reasons and need an alternative

I don't think anything in this discussion invalidates the compromise
(using tooz) we came up during the session. ZooKeeper can totally be the
tooz default in devstack (something has to be). If other tooz drivers
reach the same level of maturity one day, they could run in specific
tests and/or become the new default ?

-- 
Thierry Carrez (ttx)