Right, but that doesn't really answer the question…. On Mar 5, 2015, at 10:23 PM, Alejandro Abdelnur <tuc...@gmail.com> wrote:
> If classloader isolation is in place, then dependency versions can freely > be upgraded as won't pollute apps space (things get trickier if there is an > ON/OFF switch). > > On Thu, Mar 5, 2015 at 9:21 PM, Allen Wittenauer <a...@altiscale.com> wrote: > >> >> Is there going to be a general upgrade of dependencies? I'm thinking of >> jetty & jackson in particular. >> >> On Mar 5, 2015, at 5:24 PM, Andrew Wang <andrew.w...@cloudera.com> wrote: >> >>> I've taken the liberty of adding a Hadoop 3 section to the Roadmap wiki >>> page. In addition to the two things I've been pushing, I also looked >>> through Allen's list (thanks Allen for making this) and picked out the >>> shell script rewrite and the removal of HFTP as big changes. This would >> be >>> the place to propose features for inclusion in 3.x, I'd particularly >>> appreciate help on the YARN/MR side. >>> >>> Based on what I'm hearing, let me modulate my proposal to the following: >>> >>> - We avoid cutting branch-3, and release off of trunk. The trunk-only >>> changes don't look that scary, so I think this is fine. This does mean we >>> need to be more rigorous before merging branches to trunk. I think >>> Vinod/Giri's work on getting test-patch.sh runs on non-trunk branches >> would >>> be very helpful in this regard. >>> - We do not include anything to break wire compatibility unless (as Jason >>> says) it's an unbelievably awesome feature. >>> - No harm in rolling alphas from trunk, as it doesn't lock us to anything >>> compatibility wise. Downstreams like releases. >>> >>> I'll take Steve's advice about not locking GA to a given date, but I also >>> share his belief that we can alpha/beta/GA faster than it took for Hadoop >>> 2. Let's roll some intermediate releases, work on the roadmap items, and >>> see how we're feeling in a few months. >>> >>> Best, >>> Andrew >>> >>> On Thu, Mar 5, 2015 at 3:21 PM, Siddharth Seth <ss...@apache.org> wrote: >>> >>>> I think it'll be useful to have a discussion about what else people >> would >>>> like to see in Hadoop 3.x - especially if the change is potentially >>>> incompatible. Also, what we expect the release schedule to be for major >>>> releases and what triggers them - JVM version, major features, the need >> for >>>> incompatible changes ? Assuming major versions will not be released >> every 6 >>>> months/1 year (adoption time, fairly disruptive for downstream projects, >>>> and users) - considering additional features/incompatible changes for >> 3.x >>>> would be useful. >>>> >>>> Some features that come to mind immediately would be >>>> 1) enhancements to the RPC mechanics - specifically support for AsynRPC >> / >>>> two way communication. There's a lot of places where we re-use >> heartbeats >>>> to send more information than what would be done if the PRC layer >> supported >>>> these features. Some of this can be done in a compatible manner to the >>>> existing RPC sub-system. Others like 2 way communication probably >> cannot. >>>> After this, having HDFS/YARN actually make use of these changes. The >> other >>>> consideration is adoption of an alternate system ike gRpc which would be >>>> incompatible. >>>> 2) Simplification of configs - potentially separating client side >> configs >>>> and those used by daemons. This is another source of perpetual confusion >>>> for users. >>>> >>>> Thanks >>>> - Sid >>>> >>>> >>>> On Thu, Mar 5, 2015 at 2:46 PM, Steve Loughran <ste...@hortonworks.com> >>>> wrote: >>>> >>>>> Sorry, outlook dequoted Alejandros's comments. >>>>> >>>>> Let me try again with his comments in italic and proofreading of mine >>>>> >>>>> On 05/03/2015 13:59, "Steve Loughran" <ste...@hortonworks.com<mailto: >>>>> ste...@hortonworks.com>> wrote: >>>>> >>>>> >>>>> >>>>> On 05/03/2015 13:05, "Alejandro Abdelnur" <tuc...@gmail.com<mailto: >>>>> tuc...@gmail.com><mailto:tuc...@gmail.com>> wrote: >>>>> >>>>> IMO, if part of the community wants to take on the responsibility and >>>> work >>>>> that takes to do a new major release, we should not discourage them >> from >>>>> doing that. >>>>> >>>>> Having multiple major branches active is a standard practice. >>>>> >>>>> Looking @ 2.x, the major work (HDFS HA, YARN) meant that it did take a >>>>> long time to get out, and during that time 0.21, 0.22, got released and >>>>> ignored; 0.23 picked up and used in production. >>>>> >>>>> The 2.04-alpha release was more of a troublespot as it got picked up >>>>> widely enough to be used in products, and changes were made between >> that >>>>> alpha & 2.2 itself which raised compatibility issues. >>>>> >>>>> For 3.x I'd propose >>>>> >>>>> >>>>> 1. Have less longevity of 3.x alpha/beta artifacts >>>>> 2. Make clear there are no guarantees of compatibility from >> alpha/beta >>>>> releases to shipping. Best effort, but not to the extent that it gets >> in >>>>> the way. More succinctly: we will care more about seamless migration >> from >>>>> 2.2+ to 3.x than from a 3.0-alpha to 3.3 production. >>>>> 3. Anybody who ships code based on 3.x alpha/beta to recognise and >>>>> accept policy (2). Hadoop's "instability guarantee" for the 3.x >>>> alpha/beta >>>>> phase >>>>> >>>>> As well as backwards compatibility, we need to think about Forwards >>>>> compatibility, with the goal being: >>>>> >>>>> Any app written/shipped with the 3.x release binaries (JAR and native) >>>>> will work in and against a 3.y Hadoop cluster, for all x, y in Natural >>>>> where y>=x and is-release(x) and is-release(y) >>>>> >>>>> That's important, as it means all server-side changes in 3.x which are >>>>> expected to to mandate client-side updates: protocols, HDFS erasure >>>>> decoding, security features, must be considered complete and stable >>>> before >>>>> we can say is-release(x). In an ideal world, we'll even get the >> semantics >>>>> right with tests to show this. >>>>> >>>>> Fixing classpath hell downstream is certainly one feature I am +1 on. >>>> But: >>>>> it's only one of the features, and given there's not any design doc on >>>> that >>>>> JIRA, way too immature to set a release schedule on. An alpha schedule >>>> with >>>>> no-guarantees and a regular alpha roll, could be viable, as new >> features >>>> go >>>>> in and can then be used to experimentally try this stuff in branches of >>>>> Hbase (well volunteered, Stack!), etc. Of course instability guarantees >>>>> will be transitive downstream. >>>>> >>>>> >>>>> This time around we are not replacing the guts as we did from Hadoop 1 >> to >>>>> Hadoop 2, but superficial surgery to address issues were not considered >>>> (or >>>>> was too much to take on top of the guts transplant). >>>>> >>>>> For the split brain concern, we did a great of job maintaining Hadoop 1 >>>> and >>>>> Hadoop 2 until Hadoop 1 faded away. >>>>> >>>>> And a significant argument about 2.0.4-alpha to 2.2 protobuf/HDFS >>>>> compatibility. >>>>> >>>>> >>>>> Based on that experience I would say that the coexistence of Hadoop 2 >> and >>>>> Hadoop 3 will be much less demanding/traumatic. >>>>> >>>>> The re-layout of all the source trees was a major change there, >> assuming >>>>> there's no refactoring or switch of build tools then picking things >> back >>>>> will be tractable >>>>> >>>>> >>>>> Also, to facilitate the coexistence we should limit Java language >>>> features >>>>> to Java 7 (even if the runtime is Java 8), once Java 7 is not used >>>> anymore >>>>> we can remove this limitation. >>>>> >>>>> +1; setting javac.version will fix this >>>>> >>>>> What is nice about having java 8 as the base JVM is that it means you >> can >>>>> be confident that all Hadoop 3 servers will be JDK8+, so downstream >> apps >>>>> and libs can use all Java 8 features they want to. >>>>> >>>>> There's one policy change to consider there which is possibly, just >>>>> possibly, we could allow new modules in hadoop-tools to adopt Java 8 >>>>> languages early, provided everyone recognised that "backport to >> branch-2" >>>>> isn't going to happen. >>>>> >>>>> -Steve >>>>> >>>>> >>>> >> >>
