I would recommend to take care with this kind of changes. I didn't try Arrow in more than one year, but by then the performance was quite bad in comparison with plain byte buffer access (see http://git.net/apache-arrow-development/msg02353.html *) and there are several optimizations that the JVM (specifically, C2) does not apply when dealing with int instead of longs. One of the most commons is the loop unrolling and vectorization.
* It doesn't seem the best way to reference an old email on the list, but it is the only result shown by Google El mié., 7 ago. 2019 a las 11:42, Fan Liya (<liya.fa...@gmail.com>) escribió: > Hi Micah, > > Thanks for your effort. The performance result looks good. > > As you indicated, ArrowBuf will take additional 12 bytes (4 bytes for each > of length, write index, and read index). > Similar overheads also exist for vectors like BaseFixedWidthVector, > BaseVariableWidthVector, etc. > > IMO, such overheads are small enough to justify the change. > Let's check if there are other overheads. > > Best, > Liya Fan > > On Wed, Aug 7, 2019 at 3:30 PM Micah Kornfield <emkornfi...@gmail.com> > wrote: > > > Hi Liya Fan, > > Based on the Float8Benchmark there does not seem to be any meaningful > > performance difference on my machine. At least for me, the benchmarks > are > > not stable enough to say one is faster than the other (I've pasted > results > > below). That being said my machine isn't necessarily the most reliable > for > > benchmarking. > > > > On an intuitive level, this makes sense to me, for the most part it > seems > > like the change just moves casting from "int" to "long" further up the > > stack for "PlatformDepdendent" operations. If there are other > benchmarks > > that you think are worth running let me know. > > > > One downside performance wise I think for his change is it increases the > > size of ArrowBuf objects, which I suppose could influence cache misses at > > some level or increase the size of call-stacks, but this doesn't seem to > > show up in the benchmark.. > > > > Thanks, > > Micah > > > > Sample benchmark numbers: > > > > [New Code] > > Benchmark Mode Cnt Score Error Units > > Float8Benchmarks.copyFromBenchmark avgt 5 15.441 ± 0.469 us/op > > Float8Benchmarks.readWriteBenchmark avgt 5 14.057 ± 0.115 us/op > > > > > > [Old code] > > Benchmark Mode Cnt Score Error Units > > Float8Benchmarks.copyFromBenchmark avgt 5 16.248 ± 1.409 us/op > > Float8Benchmarks.readWriteBenchmark avgt 5 14.150 ± 0.084 us/op > > > > On Tue, Aug 6, 2019 at 1:18 AM Fan Liya <liya.fa...@gmail.com> wrote: > > > >> Hi Micah, > >> > >> Thanks a lot for doing this. > >> > >> I am a little concerned about if there is any negative performance > impact > >> on the current 32-bit-length based applications. > >> Can we do some performance comparison on our existing benchmarks? > >> > >> Best, > >> Liya Fan > >> > >> > >> On Tue, Aug 6, 2019 at 3:35 PM Micah Kornfield <emkornfi...@gmail.com> > >> wrote: > >> > >>> There have been some previous discussions on the mailing about > supporting > >>> 64-bit lengths for Java ValueVectors (this is what the IPC > specification > >>> and C++ support). I created a PR [1] that changes all APIs that I > could > >>> find that take an index to take an "long" instead of an "int" (and > >>> similarly change "size/rowcount" APIs). > >>> > >>> It is a big change, so I think it is worth discussing if it is > something > >>> we > >>> still want to move forward with. It would be nice to come to a > >>> conclusion > >>> quickly, ideally in the next few days, to avoid a lot of merge > conflicts. > >>> > >>> The reason I did this work now is the C++ implementation has added > >>> support > >>> for LargeList, LargeBinary and LargeString arrays and based on prior > >>> discussions we need to have similar support in Java before our next > >>> release. Support 64-bit indexes means we can have full compatibility > and > >>> make the most use of the types in Java. > >>> > >>> Look forward to hearing feedback. > >>> > >>> Thanks, > >>> Micah > >>> > >>> [1] https://github.com/apache/arrow/pull/5020 > >>> > >> >
