Hello! -1 Let's not ban Java Streams, for the reasons already listed.
Regards, -- Ilya Kasnacheev чт, 9 сент. 2021 г. в 10:59, Ivan Daschinsky <ivanda...@gmail.com>: > Few words about the topic. > There is a disease, quite common in the java community -- it is called the > streamosis. > But, to be honest, afear of streams is also not good. > > As for me, sometimes rewriting code completely with simple loops often > makes it more readable, understandable and usually faster. > > So I am against a complete ban of streams, but I am for using this tool > with caution. Often streams make code ugly and non-readable at all. > > > чт, 9 сент. 2021 г. в 10:50, Ivan Daschinsky <ivanda...@gmail.com>: > > > To be honest, Pavel, your benchmark is not quite correct. Please, rewrite > > it using BlackHole > > > > чт, 9 сент. 2021 г. в 10:28, Nikolay Izhikov <nizhi...@apache.org>: > > > >> +1 to ban Streams usage. > >> > >> > >> > >> > 9 сент. 2021 г., в 02:59, Valentin Kulichenko < > >> valentin.kuliche...@gmail.com> написал(а): > >> > > >> > Pavel, > >> > > >> > Quite frankly, I think we used to lean into performance too much. We > >> > generally preferred it over data consistency, project modularity and > >> code > >> > readability. Performance, of course, plays a very important rule in > >> Ignite, > >> > but it's possible to overdo anything. > >> > > >> > There are certainly parts of the project that can benefit from > features > >> > like Stream API, without significant concern over performance. CLI is > an > >> > obvious example, but I'm sure it's not the only one. > >> > > >> > That said, I don't think that banning something is productive. At the > >> same > >> > time, we should make sure we pay more attention to performance during > >> > reviews. Maybe we should have a checklist of major things to look for? > >> Not > >> > as a set of strict rules, but more as a guideline for contributors and > >> > committers. > >> > > >> > We might also want to start benchmarking the code and tracking the > >> progress. > >> > > >> > -Val > >> > > >> > On Wed, Sep 8, 2021 at 12:09 PM Pavel Tupitsyn <ptupit...@apache.org> > >> wrote: > >> > > >> >> Alexander, Ivan, > >> >> > >> >>> not very productive to assume that 100% of your code is > >> >>> on the hot path > >> >> > >> >> That is exactly what we should be doing. > >> >> When I joined Ignite community 6 years ago, this was the prevalent > >> mindset. > >> >> > >> >> I'm not sure which part of Ignite can be considered "not on a hot > >> path". > >> >> Create/alter table (mentioned above) should perform well too. > >> >> > >> >>> measured first and only then optimized > >> >>> https://wiki.c2.com/?OptimizeLater > >> >> > >> >> Extra allocations are a "death by a thousand cuts". > >> >> They add up here and there, and then there are GC pauses. > >> >> This would be hard to "optimize later". > >> >> > >> >> It is common for perf-oriented projects to avoid some techniques. > >> >> For example, LINQ (streams analog from C# with similar perf issues) > is > >> >> avoided in libraries and compilers [1]. > >> >> > >> >> [1] https://github.com/dotnet/roslyn/blob/main/CONTRIBUTING.md > >> >> > >> >> On Wed, Sep 8, 2021 at 9:49 PM Valentin Kulichenko < > >> >> valentin.kuliche...@gmail.com> wrote: > >> >> > >> >>> I don't think we should ban anything. Streams API is just a tool in > >> the > >> >>> toolbox - it should be used appropriately. It's up to the > contributor > >> and > >> >>> reviewer(s) to identify whether a particular usage might cause > >> >> performance > >> >>> issues. > >> >>> > >> >>> -Val > >> >>> > >> >>> On Wed, Sep 8, 2021 at 8:01 AM Alexander Polovtcev < > >> >>> alexpolovt...@gmail.com> > >> >>> wrote: > >> >>> > >> >>>> -1 > >> >>>> I think that it is not very productive to assume that 100% of your > >> code > >> >>> is > >> >>>> on the hot path, it would be impossible to write and maintain. > Humans > >> >> are > >> >>>> not very good at guessing where the performance bottlenecks are, so > >> the > >> >>>> performance of the possible hot paths should be measured first and > >> only > >> >>>> then optimized and documented. > >> >>>> > >> >>>> On Wed, Sep 8, 2021 at 5:53 PM Ivan Pavlukhin <vololo...@gmail.com > > > >> >>> wrote: > >> >>>> > >> >>>>> Does not this trivial strategy work for us? > >> >>>>> https://wiki.c2.com/?OptimizeLater > >> >>>>> > >> >>>>> 2021-09-08 13:52 GMT+03:00, Andrey Gura <ag...@apache.org>: > >> >>>>>> Agree that any additional object creation on a hot path could be > a > >> >>>>>> problem. So hot path should not contain stream API and any other > >> >>>>>> potentially problem code (e.g. iterator instead of for by index). > >> >>>>>> > >> >>>>>> On Wed, Sep 8, 2021 at 1:45 PM Pavel Tupitsyn < > >> >> ptupit...@apache.org> > >> >>>>> wrote: > >> >>>>>>> > >> >>>>>>> Ok, maybe a total ban is overkill, but right now streams are > used > >> >>> even > >> >>>>> on > >> >>>>>>> some hot paths like getAllAsync [1]. > >> >>>>>>> > >> >>>>>>> Another issue is that Collectors.toList() and other variants > don't > >> >>>>> accept > >> >>>>>>> capacity, and we end up with unnecessary reallocations of > >> >> underlying > >> >>>>>>> arrays. > >> >>>>>>> > >> >>>>>>> [1] > >> >>>>>>> > >> >>>>> > >> >>>> > >> >>> > >> >> > >> > https://github.com/apache/ignite-3/blob/1d7d703ff2b18234b15a9a7b03104fbb73388edf/modules/table/src/main/java/org/apache/ignite/internal/table/KVBinaryViewImpl.java#L83 > >> >>>>>>> > >> >>>>>>> On Wed, Sep 8, 2021 at 1:06 PM Konstantin Orlov < > >> >>> kor...@gridgain.com> > >> >>>>>>> wrote: > >> >>>>>>> > >> >>>>>>>> Hi! > >> >>>>>>>> > >> >>>>>>>> Agree with Ivan that it’s an overkill. Code readability and > >> >>>>>>>> maintainability should have > >> >>>>>>>> the same priority as the performance (with some exceptions of > >> >>>> course). > >> >>>>>>>> > >> >>>>>>>> BTW the result of your benchmark looks quite strange. The > >> >>>> performance > >> >>>>>>>> penalty on > >> >>>>>>>> my laptop (Core i7 9750H, 6 cores up to 4.50 GHz) is 25%, not 8 > >> >>>> times: > >> >>>>>>>> > >> >>>>>>>> Benchmark Mode Cnt Score > Error > >> >>>>>>>> Units > >> >>>>>>>> JmhIncrementBenchmark.loopSum thrpt 10 32347.819 ± > 676.548 > >> >>>>>>>> ops/ms > >> >>>>>>>> JmhIncrementBenchmark.streamSum thrpt 10 24459.196 ± > 610.152 > >> >>>>>>>> ops/ms > >> >>>>>>>> > >> >>>>>>>> > >> >>>>>>>> -- > >> >>>>>>>> Regards, > >> >>>>>>>> Konstantin Orlov > >> >>>>>>>> > >> >>>>>>>> > >> >>>>>>>>> On 8 Sep 2021, at 12:23, Ivan Bessonov <bessonov...@gmail.com > >> >>> > >> >>>>> wrote: > >> >>>>>>>>> > >> >>>>>>>>> Hello Igniters, > >> >>>>>>>>> > >> >>>>>>>>> I object, banning streams is an overkill. I would argue that > >> >>> most > >> >>>> of > >> >>>>>>>>> the > >> >>>>>>>>> code > >> >>>>>>>>> is not on hot paths and that allocations in TLAB don't create > >> >>> much > >> >>>>>>>> pressure > >> >>>>>>>>> on GC. > >> >>>>>>>>> > >> >>>>>>>>> Streams must be used cautiously, developers should know > >> >> whether > >> >>>> they > >> >>>>>>>>> write hot methods or not. And if methods are not hot, code > >> >>>>> simplicity > >> >>>>>>>> must > >> >>>>>>>>> be > >> >>>>>>>>> the first priority. I don't want Ignite 3 code to look like > >> >>>> Ignite 2 > >> >>>>>>>> code, > >> >>>>>>>>> where > >> >>>>>>>>> people would iterate over Lists using explicit access by > >> >>> indexes, > >> >>>>>>>> because it > >> >>>>>>>>> saves them a single Iterator allocation. That's absurd. > >> >>>>>>>>> > >> >>>>>>>>> ср, 8 сент. 2021 г. в 11:43, Pavel Tupitsyn < > >> >>> ptupit...@apache.org > >> >>>>> : > >> >>>>>>>>> > >> >>>>>>>>>> Igniters, > >> >>>>>>>>>> > >> >>>>>>>>>> Java streams are known to be slower and cause more GC > >> >> pressure > >> >>>> than > >> >>>>>>>>>> an > >> >>>>>>>>>> equivalent loop. > >> >>>>>>>>>> Below is a simple filter/map/reduce scenario (code [1]): > >> >>>>>>>>>> > >> >>>>>>>>>> * Benchmark > >> >>>>> Mode > >> >>>>>>>> Cnt > >> >>>>>>>>>> Score Error Units > >> >>>>>>>>>> > >> >>>>>>>>>> * StreamVsLoopBenchmark.loopSum > >> >>>>>>>>>> thrpt > >> >>>>>>>> 3 > >> >>>>>>>>>> 7987.016 ± 293.013 ops/ms > >> >>>>>>>>>> * StreamVsLoopBenchmark.loopSum:·gc.alloc.rate > >> >>>>>>>>>> thrpt > >> >>>>>>>> 3 > >> >>>>>>>>>> ≈ 10⁻⁴ MB/sec > >> >>>>>>>>>> * StreamVsLoopBenchmark.loopSum:·gc.count > >> >>>>>>>>>> thrpt > >> >>>>>>>> 3 > >> >>>>>>>>>> ≈ 0 counts > >> >>>>>>>>>> > >> >>>>>>>>>> * StreamVsLoopBenchmark.streamSum > >> >>>>>>>>>> thrpt > >> >>>>>>>> 3 > >> >>>>>>>>>> 1060.244 ± 36.485 ops/ms > >> >>>>>>>>>> * StreamVsLoopBenchmark.streamSum:·gc.alloc.rate > >> >>>>>>>>>> thrpt > >> >>>>>>>> 3 > >> >>>>>>>>>> 315.819 ± 10.844 MB/sec > >> >>>>>>>>>> * StreamVsLoopBenchmark.streamSum:·gc.count > >> >>>>>>>>>> thrpt > >> >>>>>>>> 3 > >> >>>>>>>>>> 55.000 counts > >> >>>>>>>>>> > >> >>>>>>>>>> Loop is several times faster and does not allocate at all. > >> >>>>>>>>>> > >> >>>>>>>>>> 1. Performance is one of the most important features of our > >> >>>>> product. > >> >>>>>>>>>> 2. Most of our APIs will be on the hot path. > >> >>>>>>>>>> > >> >>>>>>>>>> One can argue about performance differences in real-world > >> >>>>> scenarios, > >> >>>>>>>>>> but increasing GC pressure just to make the code a little bit > >> >>>> nicer > >> >>>>>>>>>> is > >> >>>>>>>>>> unacceptable. > >> >>>>>>>>>> > >> >>>>>>>>>> I propose to ban streams usage in the codebase (except for > >> >> the > >> >>>>>>>>>> tests). > >> >>>>>>>>>> > >> >>>>>>>>>> Thoughts, objections? > >> >>>>>>>>>> > >> >>>>>>>>>> [1] > >> >>>>>>>>>> > >> >>>> https://gist.github.com/ptupitsyn/5934bbbf8f92ac4937e534af9386da97 > >> >>>>>>>>>> > >> >>>>>>>>> > >> >>>>>>>>> > >> >>>>>>>>> -- > >> >>>>>>>>> Sincerely yours, > >> >>>>>>>>> Ivan Bessonov > >> >>>>>>>> > >> >>>>>>>> > >> >>>>>> > >> >>>>> > >> >>>>> > >> >>>>> -- > >> >>>>> > >> >>>>> Best regards, > >> >>>>> Ivan Pavlukhin > >> >>>>> > >> >>>> > >> >>>> > >> >>>> -- > >> >>>> With regards, > >> >>>> Aleksandr Polovtcev > >> >>>> > >> >>> > >> >> > >> > >> > > > > -- > > Sincerely yours, Ivan Daschinskiy > > > > > -- > Sincerely yours, Ivan Daschinskiy >
