On Thu, Jan 28, 2016 at 6:45 AM, Jake Farrell <jfarr...@apache.org> wrote:
> +1 to making this apart of Thrift, i'm happy to help shepard this on the > Thrift side and get it in as soon as its ready > I've filed https://issues.apache.org/jira/browse/THRIFT-3583 to use as the basis for discussion of this feature over in the Apache Thrift project. I looked at the problem a bit and noted some challenges. > > -Jake > > On Wed, Jan 27, 2016 at 8:08 PM, Maxim Khutornenko <ma...@apache.org> > wrote: > >> I am +1 to making immutable thrift objects solely based on perf numbers. >> >> My biggest concern though is maintenance of a pretty intricate codebase, >> especially when it comes to upgrading any of the frameworks involved. >> Bill's suggestion to explore paths to make this a part of Apache Thrift >> sounds great to me. >> >> On Wed, Jan 27, 2016 at 5:00 PM, Bill Farner <wfar...@apache.org> wrote: >> >> > Tony - this would not be a technical fork so much as a spiritual fork. >> > While we would have our own bugs to work out, the only upstream exposure >> > would be IDL or wire format changes. >> > >> > On Wed, Jan 27, 2016 at 4:58 PM, Tony Dong <td...@twitter.com.invalid> >> > wrote: >> > >> > > Awesome performance numbers! I don't particularly know the logistics >> of >> > > upstreaming a change like this, but optimistically I would suggest >> > > upstreaming it to Apache Thrift if possible. >> > > >> > > As someone that maintains a fork of a thrift compiler(fork of >> scrooge), I >> > > have to say that it's not that fun. There's a lot of custom code that >> > needs >> > > to be maintained and a bunch of work to rebase the code periodically. >> > > >> > > >> > > >> > > On Wed, Jan 27, 2016 at 4:51 PM, Bill Farner <wfar...@apache.org> >> wrote: >> > > >> > > > Firstly - thanks for the clean organization and delineation of >> steps in >> > > > this change. Top notch work! >> > > > >> > > > Some of the performance improvements are very nice; and in a >> > particularly >> > > > hot code path. I will wager a guess that the majority of the >> savings >> > is >> > > in >> > > > avoiding what amounts to copy constructors between mutable and >> > immutable >> > > > types. I further wager there are alternative approaches we could >> weigh >> > > to >> > > > achieve those performance improvements. As an example - you note >> above >> > > > that we could provide a patch to Apache Thrift. Depending how much >> > > > performance inspires our decision here, it will be prudent to >> evaluate >> > > > alternatives. >> > > > >> > > > I think there are (at least) two major issues worth discussing - >> code >> > > > volume (which you note) and an increase in logical complexity. This >> > will >> > > > leave us with a bifurcation in code generation tooling (custom+swift >> > for >> > > > Java, Apache Thrift for python and js). It's difficult to quantify >> the >> > > > downside of that, but it seems like an unfortunate state with >> potential >> > > for >> > > > compatibility risks. >> > > > >> > > > >> > > > On Wed, Jan 27, 2016 at 2:45 PM, Zameer Manji <zma...@apache.org> >> > wrote: >> > > > >> > > > > Some high level comments without looking at the code. >> > > > > >> > > > > I'm in favor from abandoning the thrift generated java code in >> favor >> > of >> > > > > immutable objects. I think it is easier to reason about and will >> > ensure >> > > > we >> > > > > have less errors in our code. If I understand correctly, the >> ProtoBuf >> > > > > format does this by default, so there some precedent for this >> style >> > of >> > > > code >> > > > > generation already. >> > > > > >> > > > > I think using Facebook's swift is the best approach here. I would >> be >> > > > > hesitant to accept any custom code generation that involved us >> > parsing >> > > > > thrift IDL files or thrift formats over the wire because I poses a >> > very >> > > > > high maintenance burden. >> > > > > >> > > > > I also think generating the MyBatis mutable classes is superior to >> > our >> > > > > current strategy of manually creating them. >> > > > > >> > > > > Finally, the performance improvements look fantastic. As an >> operator >> > > of a >> > > > > large cluster I am excited to see wholesale performance >> improvements >> > > as I >> > > > > am always concerned that my cluster is approaching the limits of >> what >> > > > > Aurora can handle safely. >> > > > > >> > > > > Overall, I think this change merits a serious discussion from all >> > > > > contributors. >> > > > > >> > > > > On Tue, Jan 26, 2016 at 9:19 PM, John Sirois <jsir...@apache.org> >> > > wrote: >> > > > > >> > > > > > On Tue, Jan 26, 2016 at 8:47 PM, John Sirois < >> jsir...@apache.org> >> > > > wrote: >> > > > > > >> > > > > > > Context: Aurora uses the official Apache Thrift compiler today >> > > plus a >> > > > > > > home-grown python code generator [1] for immutable "entity" >> (I*) >> > > > > > wrappers. >> > > > > > > >> > > > > > > The proposal is to switch from using the Apache Thrift code >> > > generator >> > > > > to >> > > > > > a >> > > > > > > home grown generator. The proposal comes with a concrete >> example >> > > in >> > > > > the >> > > > > > > form of the actual RBs to effect this change: >> > > > > > > 1. A custom java thrift code generator: >> > > > > > > https://reviews.apache.org/r/42748/ >> > > > > > > 2. A custom MyBatis binding code generator powered by 1 above: >> > > > > > > https://reviews.apache.org/r/42749/ >> > > > > > > 3. Integration of 1 & 2 above into the Aurora codebase: >> > > > > > > https://reviews.apache.org/r/42756/ >> > > > > > > >> > > > > > > Since the RBs are large, I wanted to provide some extra >> context >> > on >> > > > the >> > > > > > > idea at a higher level. I provide rationale, pros and cons >> below >> > > for >> > > > > > those >> > > > > > > interested in the idea but wary of diving in on code review >> until >> > > the >> > > > > > idea >> > > > > > > itself passes a sniff test. >> > > > > > > Thanks in advance for your feedback - and if we get there - >> for >> > > your >> > > > > > > review effort. >> > > > > > > >> > > > > > >> > > > > > I just added wfarner and zmanji as reviewers for the 3 RBs above >> > > since >> > > > > > they've expressed direct interest. Happy to add others, just >> speak >> > > up >> > > > or >> > > > > > else just comment on the reviews as you see fit. >> > > > > > I'll formally only submit if 1st this email thread reaches >> > consensus, >> > > > and >> > > > > > second, reviews are approved. >> > > > > > >> > > > > > == >> > > > > > > >> > > > > > > In the course of an initial run at creating a first-class >> > REST-like >> > > > > > > scheduler interface [2] I came to the conclusion generating >> the >> > > json >> > > > > API >> > > > > > > from the thrift one might be a good path. That idea has been >> > > > scrapped >> > > > > > with >> > > > > > > community feedback, but an initial experiment in custom thrift >> > > > code-gen >> > > > > > for >> > > > > > > java that accompanied that idea seemed worth pursuing for its >> own >> > > > > > > independent benefits, chief among these being 1st class >> immutable >> > > > > thrift >> > > > > > > structs and the ability to leverage thrift annotations. >> > > > > > > >> > > > > > > Immutability: >> > > > > > > The benefits of having an immutable by default data model are >> the >> > > > > > standard >> > > > > > > ones; namely, its trivial to reason about safety of concurrent >> > > > > operations >> > > > > > > on the data model, stability of collections containing data >> model >> > > > > > entities >> > > > > > > and it opens up straight-forward optimizations that are easy >> to >> > > > reason >> > > > > > > about. >> > > > > > > An example optimization is caching hashCodes for the immutable >> > > thrift >> > > > > > > structs. This was done after comparing jmh benchmarks run >> > against >> > > > > master >> > > > > > > and then again against the proposal branch. Perf was >> comparable >> > - >> > > > > within >> > > > > > > 10% plus and minus depending on the benchmark, but with the >> > > > > optimization >> > > > > > > added many benchmarks showed pronounced improvement in the >> > proposal >> > > > > > branch >> > > > > > > [3]. The optimization is clearly safe and was quick and easy >> to >> > > > > > > implement. Further optimizations can be experimented with in >> a >> > > > > > > straightforward way. >> > > > > > > >> > > > > > > Thrift Annotations: >> > > > > > > The thrift IDL grammar has supported these for quite some >> time, >> > but >> > > > > they >> > > > > > > are not plumbed to the generated java code. Uses are many and >> > > > > varied. I >> > > > > > > initially had my eye on annotation of thrift services with >> REST >> > > > verbs, >> > > > > > > routes, etc - but immediately we can leverage these >> annotations >> > to >> > > > kill >> > > > > > > AnnotatedAuroraAdmin and reduce the amount of MyBatis binding >> > code >> > > > that >> > > > > > > needs to be maintained. >> > > > > > > >> > > > > > > There are a few downsides to switching to our own java thrift >> > code >> > > > gen: >> > > > > > > 1. We own more code to maintain: Even though we have the >> custom >> > > > python >> > > > > > > "immutable" wrapper generator [1] today, this new generator - >> > even >> > > > with >> > > > > > the >> > > > > > > python generator removed - represents a 5-6x increase in line >> > count >> > > > of >> > > > > > > custom code (~4.1k lines of code and tests in the new custom >> gen, >> > > > ~700 >> > > > > > > lines in the existing python custom gen) >> > > > > > > 2. We conceptually fork from a sibling Apache project. >> > > > > > > >> > > > > > > The fork could be mitigated by turning our real experience >> > > iterating >> > > > > the >> > > > > > > custom code generator into a well-founded patch back into the >> > > Apache >> > > > > > Thrift >> > > > > > > project, but saying we'll do that is easier than following >> > through >> > > > and >> > > > > > > actually doing it. >> > > > > > > >> > > > > > > == >> > > > > > > Review guide / details: >> > > > > > > >> > > > > > > The technology stack: >> > > > > > > The thrift IDL parsing and thrift wire parsing are both >> handled >> > by >> > > > the >> > > > > > > Facebook swift project [4]. We only implement the middle bit >> > that >> > > > > > > generates java code stubs. This gives higher confidence that >> the >> > > > > tricky >> > > > > > > bits out at either edge are done right. >> > > > > > > The thrift struct code generation is done using Square's >> javapoet >> > > [5] >> > > > > in >> > > > > > > favor of templating for the purpose of easier to read >> generator >> > > code. >> > > > > > This >> > > > > > > characterization is debatable though and template are >> certainly >> > > more >> > > > > > > flexible the minute you need to gen a second language (say we >> > like >> > > > this >> > > > > > and >> > > > > > > want to do javascript codegen this way too for example). >> > > > > > > The MyBatis codegen is forced by the thrift codegen for >> technical >> > > > > > > reasons. In short, there is no simple way to teach MyBatis to >> > read >> > > > and >> > > > > > > write immutable objects with builders. So the MyBatis code is >> > > > > generated >> > > > > > > via an annotation processor that runs after thrift code gen, >> but >> > > > > reading >> > > > > > > thrift annotations that survive that codegen process. >> > > > > > > The codegen unit testing is done with the help of Google's >> > > > > compile-tester >> > > > > > > [6]. NB that this has an expected output comparison that >> checks >> > > the >> > > > > > > generated AST and not the text, so its fairly lenient. >> > Whitepsace >> > > > and >> > > > > > > comments certainly don't matter. >> > > > > > > >> > > > > > > Review strategy: >> > > > > > > The code generator RBs (#1 & #2 in the 3 part series) are >> > probably >> > > > > easier >> > > > > > > to review looking at samples of the generated code. Both the >> > > thrift >> > > > > > > codegen and MyBatis codegen samples are conveniently >> contained in >> > > the >> > > > > > > MyBatis codegen RB (#2: https://reviews.apache.org/r/42749/). >> > The >> > > > > unit >> > > > > > > test uses resource files that contain both the thrift codegen >> > > inputs >> > > > > the >> > > > > > > annotation processor runs over and the annotation processor >> > > expected >> > > > > > > outputs - the MyBatis peer classes. So have a look there if >> you >> > > > need >> > > > > > > something concrete and don't want to patch the RBs in and >> > actually >> > > > run >> > > > > > the >> > > > > > > codegen (`./gradlew api:compileJava`). >> > > > > > > The conversion RB (#3) is large but the changes are mainly >> > > mechanical >> > > > > > > conversions from the current mutable thrift + I* wrappers to >> pure >> > > > > > immutable >> > > > > > > thrift mutated via `.toBuilder` and `.with`'er methods. The >> main >> > > > > changes >> > > > > > > of note are to the portions of the codebase tightly tied to >> > thrift >> > > > as a >> > > > > > > technology: >> > > > > > > + Gson/thrift converters >> > > > > > > + Shiro annotated auth param interception >> > > > > > > + Thrift/Servlet binding >> > > > > > > >> > > > > > > [1] >> > > > > > > >> > > > > > >> > > > > >> > > > >> > > >> > >> https://github.com/apache/aurora/blob/master/src/main/python/apache/aurora/tools/java/thrift_wrapper_codegen.py >> > > > > > > [2] https://issues.apache.org/jira/browse/AURORA-987 >> > > > > > > [3] >> > > > > > > >> > > > > > >> > > > > >> > > > >> > > >> > >> https://docs.google.com/spreadsheets/d/1-CYMnEjzknAsY5_r_NVX8r85wxtrEByZ5YRiAbgMhP0/edit#gid=840229346 >> > > > > > > [4] https://github.com/facebook/swift >> > > > > > > [5] https://github.com/square/javapoet >> > > > > > > [6] https://github.com/google/compile-testing >> > > > > > > >> > > > > > >> > > > > > -- >> > > > > > Zameer Manji >> > > > > > >> > > > > > >> > > > > >> > > > >> > > >> > >> > > -- John Sirois 303-512-3301
