Let us double-check current options. Maybe I'm mistaken about Alex Plehanov's idea.
Let's introduce the following variables and functions: data - our block. OldImpl(data) = X NewImpl(data) = Y NewImpl(data) ^ C = Y ^ C, where C is constant, ^ is bitwise XOR operation. And NewImpl(data) ^ C = X = OldImpl(data) So new and old implementations give us X in all cases, we don't need any compatibility mode. Let's try to adopt new fast implementation with C constant. Evgeniy, would you like to try? вт, 21 авг. 2018 г. в 15:51, Sergey Kozlov <skoz...@gridgain.com>: > Alex > > In that case the data becomes in unpredictable state (mix of new and old > methods) and there's a chance that some partitions will be never touched > and never converted. It will force us always support old compression. > I suppose the explicit conversion that clearly say what is happening now > and may be warn that the db files should backed up before version upgrade. > > Also I think AI 3.0 will have set of incompatible changes that give us a > chance to add an upgrade procedure where compression method update among > other stuff will take into account. > > On Tue, Aug 21, 2018 at 11:58 AM, Alex Plehanov <plehanov.a...@gmail.com> > wrote: > > > Sergey, converting data also force us to introduce some flag to WAL > > segments/records or convert WAL segments too. WAL segments can be > archived, > > they also can be compressed. > > IMO we better should not introduce any compatibility modes, left data as > is > > and always just convert crc value returned by zip.CRC32 to old format > (xor > > it) at runtime. > > > > 2018-08-21 0:12 GMT+03:00 Sergey Kozlov <skoz...@gridgain.com>: > > > > > Dmitriy > > > > > > Due to significant improvement and to reduce the number supported > > > modes/options would be good to convert the data at the moment of > upgrade. > > > > > > On Tue, Aug 21, 2018 at 12:03 AM, Dmitriy Setrakyan < > > dsetrak...@apache.org > > > > > > > wrote: > > > > > > > Sergey, that was precisely my comment in the ticket: > > > > > > > > Can we add this option without breaking compatibility with previous > > > > page/storage formats? If not, then this should support both > > > implementation. > > > > The default should be the new fastest implementation, but if we > > encounter > > > > the older, slower one, then we should print out a warning in the log > > and > > > > automatically switch to the older implementation. > > > > > > > > On Mon, Aug 20, 2018 at 1:58 PM, Sergey Kozlov <skoz...@gridgain.com > > > > > > wrote: > > > > > > > > > Hi Igniters > > > > > > > > > > I suppose that'll break compatibility for LFS (PDS). > > > > > > > > > > Do we plan to provide a migration guide w/o data loss for upgrade > AI > > > 2.x > > > > to > > > > > 3.0? > > > > > > > > > > On Mon, Aug 20, 2018 at 11:46 PM, Dmitriy Setrakyan < > > > > dsetrak...@apache.org > > > > > > > > > > > wrote: > > > > > > > > > > > I commented in the ticket: https://issues.apache.org/ > > > > > > jira/browse/IGNITE-9272 > > > > > > > > > > > > It if can integrate it correctly, according to my comment, in 2.7 > > > > > release, > > > > > > it would be great. Otherwise, let's plan this change for 3.0 > > release. > > > > > > > > > > > > D. > > > > > > > > > > > > On Mon, Aug 20, 2018 at 3:50 AM, Eduard Shangareev < > > > > > > eduard.shangar...@gmail.com> wrote: > > > > > > > > > > > > > Hi, > > > > > > > > > > > > > > I have checked the benchmark and it shows great performance > boost > > > on > > > > my > > > > > > > laptop! > > > > > > > > > > > > > > +1 for this change. > > > > > > > > > > > > > > On Tue, Aug 14, 2018 at 9:01 PM Dmitriy Pavlov < > > > > dpavlov....@gmail.com> > > > > > > > wrote: > > > > > > > > > > > > > > > Hi Evgeniy, > > > > > > > > > > > > > > > > Thank you. I see that the ticket is unassigned. > > > > > > > > > > > > > > > > Would you like to contribute PR to be macro-benchmarked with > > > > Ignite? > > > > > > > > > > > > > > > > Sincerely, > > > > > > > > Dmitriy Pavlov > > > > > > > > > > > > > > > > вт, 14 авг. 2018 г. в 20:57, Евгений Станиловский > > > > > > > > <arzamas...@mail.ru.invalid>: > > > > > > > > > > > > > > > > > I fill the ticket, bench code attached there. > > > > > > > > > https://issues.apache.org/jira/browse/IGNITE-9272 > > > > > > > > > Thanks! > > > > > > > > > > > > > > > > > > > > > > > > > > > >Has anyone else run the benchmark and reproduced the > > > performance > > > > > > > > > >difference? > > > > > > > > > > > > > > > > > > > >On Tue, Aug 14, 2018 at 8:16 AM, Dmitriy Pavlov < > > > > > > > dpavlov....@gmail.com > > > > > > > > > > > > > > > > > > >wrote: > > > > > > > > > > > > > > > > > > > >> It depends. > > > > > > > > > >> > > > > > > > > > >> CRC is a CPU-intensive operation, while WAL logging and > > page > > > > > store > > > > > > > > write > > > > > > > > > >> are mostly about IO speed. > > > > > > > > > >> > > > > > > > > > >> In the same time, it can make the huge impact on > machines > > > with > > > > > > fast > > > > > > > IO > > > > > > > > > >> and > > > > > > > > > >> slow CPU. So if we can apply change proposed by Evgeniy > > and > > > > > Alexey > > > > > > > it > > > > > > > > > >> could > > > > > > > > > >> benefit performance because we save CPU. Later we can > use > > > it's > > > > > > power > > > > > > > > in > > > > > > > > > a > > > > > > > > > >> more efficient manner (e.g. with compression). > > > > > > > > > >> > > > > > > > > > >> вт, 14 авг. 2018 г. в 14:03, Yakov Zhdanov < > > > > > yzhda...@apache.org > > > > > > >: > > > > > > > > > >> > > > > > > > > > >> > Guys, what time in % does crc calculation take in WAL > > > > logging > > > > > > > > process? > > > > > > > > > >> > > > > > > > > > > >> > --Yakov > > > > > > > > > >> > > > > > > > > > > >> > 2018-08-14 13:37 GMT+03:00 Dmitriy Pavlov < > > > > > > dpavlov....@gmail.com > > > > > > > > >: > > > > > > > > > >> > > > > > > > > > > >> > > Hi Alex, thank you for this idea. > > > > > > > > > >> > > > > > > > > > > > >> > > Evgeniy, Alex, would you like to submit the patch > with > > > > > > bypassing > > > > > > > > > >> > > implementation differences to keep compatibility? > > > > > > > > > >> > > > > > > > > > > > >> > > Sincerely, > > > > > > > > > >> > > Dmitriy Pavlov > > > > > > > > > >> > > > > > > > > > > > >> > > вт, 14 авг. 2018 г. в 12:06, Alex Plehanov < > > > > > > > > > plehanov.a...@gmail.com >: > > > > > > > > > >> > > > > > > > > > > > >> > > > Hello, Igniters! > > > > > > > > > >> > > > > > > > > > > > > >> > > > In java8 java.lang.zip.CRC32 methods become > > intrinsic, > > > > > > > moreover > > > > > > > > > new > > > > > > > > > >> > > > "update" method, which use ByteBuffer was > > introduced. > > > > > Since > > > > > > we > > > > > > > > > >> moved > > > > > > > > > >> to > > > > > > > > > >> > > > java8, perhaps we really can get performance boost > > by > > > > > using > > > > > > > > > >> standard > > > > > > > > > >> > > > java.lang.zip.CRC32 instead of PureJavaCrc32. > > > > > > > > > >> > > > > > > > > > > > > >> > > > About compatibility: looks like PureJavaCrc32 > > > implements > > > > > the > > > > > > > > same > > > > > > > > > >> > > algorithm > > > > > > > > > >> > > > as java.lang.zip.CRC32. These two implementations > > uses > > > > the > > > > > > > same > > > > > > > > > >> > > polynomial > > > > > > > > > >> > > > and the same initial value. The only difference is > > > final > > > > > xor > > > > > > > > mask > > > > > > > > > >> > > > (0xFFFFFFFF for java.lang.zip.CRC32). So, we can > > > easily > > > > > > > convert > > > > > > > > > >> from > > > > > > > > > >> > > > PureJavaCrc32 > > > > > > > > > >> > > > to standard CRC32 and vice versa, using this > > > expression: > > > > > > crc32 > > > > > > > > ^= > > > > > > > > > >> > > > 0xFFFFFFFF > > > > > > > > > >> > > > > > > > > > > > > >> > > > > > > > > > > > > >> > > > 2018-08-14 0:19 GMT+03:00 Eduard Shangareev < > > > > > > > > > >> > eduard.shangar...@gmail.com > > > > > > > > > >> > > >: > > > > > > > > > >> > > > > > > > > > > > > >> > > > > Evgeniy, > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > Could you share benchmark code? And please share > > > what > > > > > > > version > > > > > > > > of > > > > > > > > > >> JVM > > > > > > > > > >> > > > > you have used. > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > On Mon, Aug 13, 2018 at 10:44 PM Zhenya > > > > > > > > > >> < arzamas...@mail.ru.invalid > > > > > > > > > >> > > > > > > > > > > >> > > > > wrote: > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > I think it would break backward compatibility, > > as > > > > > > Nikolay > > > > > > > > > >> mentioned > > > > > > > > > >> > > > above > > > > > > > > > >> > > > > > we would take exception here: > > > > > > > > > >> > > > > > > > > > > > > > > >> > > > > > [1] > > > > > > > > > >> > > > > > > > > > > > > > > >> > > > > > https://github.com/apache/ > > > > > ignite/blob/master/modules/ > > > > > > > > > >> > > > > core/src/main/java/org/apache/ > > > > > ignite/internal/processors/ > > > > > > > > > >> > > > > cache/persistence/file/FilePageStore.java#L372 > > > > > > > > > >> > > > > > > > > > > > > > > >> > > > > > thats why i question for community thoughts > > here. > > > > > > > > > >> > > > > > > > > > > > > > > >> > > > > > > Hi Evgeniy, > > > > > > > > > >> > > > > > > > > > > > > > > > >> > > > > > > would you like to submit a patch with CRC32 > > > > > > > implementation > > > > > > > > > >> > change? > > > > > > > > > >> > > > > > > > > > > > > > > > >> > > > > > > Sincerely, > > > > > > > > > >> > > > > > > Dmitriy Pavlov > > > > > > > > > >> > > > > > > > > > > > > > > > >> > > > > > > пн, 13 авг. 2018 г. в 22:08, Евгений > > > Станиловский > > > > > > > > > >> > > > > > > < arzamas...@mail.ru.invalid >: > > > > > > > > > >> > > > > > > > > > > > > > > > >> > > > > > >> Hi, igniters, i wrote a simple bench, looks > > > like > > > > > > > > > >> PureJavaCrc32 > > > > > > > > > >> > has > > > > > > > > > >> > > > > > >> performance problems in compatible with > > > > zip.CRC32. > > > > > > > > > >> > > > > > >> > > > > > > > > > >> > > > > > >> Benchmark Mode Cnt Score Error Units > > > > > > > > > >> > > > > > >> BenchmarkCRC.Crc32 avgt 5 1088914.540 ± > > > > 368851.822 > > > > > > > ns/op > > > > > > > > > >> > > > > > >> BenchmarkCRC.pureJavaCrc32 avgt 5 > > 6619408.049 ± > > > > > > > > 3746712.210 > > > > > > > > > >> > ns/op > > > > > > > > > >> > > > > > >> > > > > > > > > > >> > > > > > >> thoughts? > > > > > > > > > >> > > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > >> > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > Евгений Станиловский > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > Sergey Kozlov > > > > > GridGain Systems > > > > > www.gridgain.com > > > > > > > > > > > > > > > > > > > > > -- > > > Sergey Kozlov > > > GridGain Systems > > > www.gridgain.com > > > > > > > > > -- > Sergey Kozlov > GridGain Systems > www.gridgain.com >
