Even just writing about what objective tests might look like would be a good start! I'm happy to read draft posts by anyone who wishes to write on the topic.
C On Wed, Feb 22, 2017 at 9:36 AM, Jordan Zimmerman < [email protected]> wrote: > IMO there is tremendous FUD in the etcd world. It's the new cool toy and > ZK feels old. To suggest that ZK does not do Service Discovery is > ludicrous. That was one of the very first Curator recipes. > > It might be useful to counter this trend objectively. I'd be interested in > helping. Anyone else? We can create objective tests that compare common use > cases. > > ==================== > Jordan Zimmerman > > > On Feb 22, 2017, at 11:21 AM, Camille Fournier <[email protected]> > wrote: > > > > I think that my biggest feeling about this blog post (besides not > > disclosing the disk setup clearly) is that, ZK is really not designed to > > have massive write throughput. I would not traditionally recommend > someone > > use ZK in that manner. If we think that evolving it to be useful for such > > workloads would be good, it could be an interesting community discussion, > > but it's really not the purpose of the system design. > > > > I'd love to see a more read/write mixed load test for the systems, as > well > > as a blog post about why you might choose different systems for different > > workloads. I think developers have a hard time really understanding the > > tradeoffs they are choosing in these systems, because of the nuance > around > > them. > > > > For me, I'm more concerned about the fact that I saw a talk yesterday > that > > mentioned both etcd and consul as options for service discovery but not > ZK. > > That feels like a big hit for our community. Orthogonal to this topic, > just > > feels worth mentioning. > > > > C > > > > On Wed, Feb 22, 2017 at 4:05 AM, Alexander Binzberger < > > [email protected]> wrote: > > > >> 1. Seams like it might make sense to increase snapCount for those tests. > >> > >> 2. ZK write performance also depends on the number of watches - afaik. > >> This is not mentioned and not tested. > >> > >> 3. Does it really make sense to "blast" the store? Wouldn't it make more > >> sense to compare fixed write/read per clients rates? > >> > >> > >> > >>> Am 22.02.2017 um 05:53 schrieb Michael Han: > >>> > >>> Kudus to etcd team for making this blog and thanks for sharing. > >>> > >>> I feel like they're running a questionable configuration. > >>>>> > >>>> Looks like the test configuration > >>> <https://github.com/coreos/dbtester/blob/89eb8d31addff1d9538 > >>> 235c20878a8637f24608c/agent/agent_zookeeper.go#L29> > >>> does not have separate directory for transaction logs and snapshots as > it > >>> does not have configuration for dataLogDir. So the configuration is not > >>> optimal. Would be interesting to see the numbers with updated > >>> configuration. > >>> > >>> They mention that ZK snapshots "stop the world", and maybe I'm > mistaken, > >>>>> but > >>>>> > >>>> I didn't think that was right > >>> > >>> Right, ZK snapshots does not block processing pipeline as it is fuzzy > and > >>> it is done in a separate thread. The warning message "*To busy to snap, > >>> skipping*" mentioned in the blog is a sign that a snap shot is also > >>> generating in progress, which could be caused by the write contentions > >>> created from serializing transaction logs that leads to longer than > >>> expected snap shot generation. So "stop the world" is a side effect of > >>> resource contention, but not a design intention IMO. > >>> > >>> Also the blog mentions ZooKeeper as a key value store and I also want > to > >>> point out that ZooKeeper is more than a (metadata) key value store has > >>> features such as sessions, ephemerals, and watchers, and these design > >>> choices were made I believe to make ZK more useful as a coordination > >>> kernel, and these design choice also (negatively) contribute to the > >>> performance and scalability of ZooKeeper. > >>> > >>> > >>> On Tue, Feb 21, 2017 at 4:32 PM, Dan Benediktson < > >>> [email protected]> wrote: > >>> > >>> I kind of wonder about them only using one disk. I haven't experimented > >>>> with this in ZooKeeper, nor have I ever been a DBA, but with > traditional > >>>> database systems (which ZooKeeper should be basically identical to, in > >>>> this > >>>> regard), it's a pretty common recommendation to put snapshots and > TxLogs > >>>> on > >>>> different drives, for the obvious reason of avoiding one of the > biggest > >>>> problems laid out in that blog post: when snapshot happens, it > contends > >>>> with your log flushes, causing write latencies to explode. Suddenly > you > >>>> have tons more IO, and where it used to be nicely sequential, now it's > >>>> heavily randomized because of the two competing writers. It's kind of > the > >>>> nature of benchmarks that there's always something you can nitpick, > but > >>>> still, I feel like they're running a questionable configuration. > >>>> > >>>> They mention that ZK snapshots "stop the world", and maybe I'm > mistaken, > >>>> but I didn't think that was right - I thought they were just slowing > >>>> everything down because they write a lot and contend a lot. I'm pretty > >>>> sure > >>>> ZK snapshots are fuzzy over a range of transactions, and transactions > >>>> keep > >>>> applying during the snapshot, right? > >>>> > >>>> Thanks, > >>>> Dan > >>>> > >>>> On Tue, Feb 21, 2017 at 2:24 PM, Benjamin Mahler < > [email protected]> > >>>> wrote: > >>>> > >>>> I'm curious if folks here have seen the following write performance > >>>>> comparison that was done by CoreOS on etc, Consul, and ZooKeeper: > >>>>> https://coreos.com/blog/performance-of-etcd.html > >>>>> > >>>>> Sounds like performance comparison of reads and updates are coming > next. > >>>>> Are there any thoughts from folks here on this comparison so far? > >>>>> > >>>>> Thanks, > >>>>> Ben > >>>>> > >>>>> > >> -- > >> Alexander Binzberger > >> System Designer - WINGcon AG > >> Tel. +49 7543 966-119 > >> > >> Sitz der Gesellschaft: Langenargen > >> Registergericht: ULM, HRB 734260 > >> USt-Id.: DE232931635, WEEE-Id.: DE74015979 > >> Vorstand: thomasThomas Ehrle (Vorsitz), Fritz R. Paul (Stellvertreter), > >> Tobias Treß > >> Aufsichtsrat: Jürgen Maucher (Vorsitz), Andreas Paul (Stellvertreter), > >> Martin Sauter > >> > >> >
