I should have linked Druid's Travis config file for reference. Here it is: https://github.com/apache/incubator-druid/blob/master/.travis.yml
On Mon, Oct 14, 2019 at 6:53 PM Gian Merlino <[email protected]> wrote: > > So what exactly is the requirement? Our DataSketches code does compile > > under JDK8 and we have lots of customers and users using JDK 8. > > It depends on who you ask, I guess :) > > From Druid's perspective, we aren't going to be compiling your code, only > running it. So the only requirement we would ask for is that the code > _runs_ under a Java 11 runtime. Being able to compile under Java 11 is good > for future-proofing your code, though. It is starting to become more > prevalent. > > > It sounds like (as far as Unsafe is concerned) converting all the direct > > unsafe.blah() calls to static MethodHandle.invoke calls is what is > required. > > > > Is this correct? > > That is certainly part of it, I'm not 100% sure if that's all that's > needed. Btw, CI can help verify. In Druid's Travis config, we run our tests > on both JDK 8 and JDK 11. In order to make this automated testing easier, > we chose to do the work needed to compile Druid on JDK 11, even though we > still compile release builds using JDK 8 only. (If we hadn't done this > work, then we'd have to compile on 8 and test on 11, which Travis doesn't > easily support.) > > On Mon, Oct 14, 2019 at 5:51 PM leerho <[email protected]> wrote: > >> Thanks, Gian, this is VERY helpful! >> >> From my cursory glance, it appears that UnsafeUtil acquires Unsafe and >> Unsafe-class the usual way using reflection (I didn't think this would >> work >> with 9+ ), and then defines some method-handles that the other classes >> use. >> >> Will this approach allow code to compile under JDK11 and JDK8? >> >> It also seems that compiling with JDK11 is still a work in progress as the >> pom.xml clearly specifies JDK8. >> >> So what exactly is the requirement? Our DataSketches code does compile >> under JDK8 and we have lots of customers and users using JDK 8. >> >> It sounds like (as far as Unsafe is concerned) converting all the direct >> unsafe.blah() calls to static MethodHandle.invoke calls is what is >> required. >> >> Is this correct? >> >> Lee. >> >> >> >> >> >> >> >> >> >> >> On Mon, Oct 14, 2019 at 2:07 PM Gian Merlino <[email protected]> wrote: >> >> > And nobody should be using the Oracle JDK without a commercial >> relationship >> > with Oracle, its license is a nightmare. >> > >> > On Mon, Oct 14, 2019 at 2:04 PM Gian Merlino <[email protected]> wrote: >> > >> > > Oracle and OpenJDK builds behave the same as each other now. The >> > > differences are in terms of licensing, length of support, and release >> > > cadence. IMO most Java devs should be using one of the third-party >> > OpenJDK >> > > distributions (e.g. Corretto, Zulu, AdoptOpenJDK) rather than vanilla >> > > OpenJDK these days, because of the new OpenJDK policy that public >> updates >> > > will cease for major versions after 6 months. >> > > >> > > On Mon, Oct 14, 2019 at 11:07 AM leerho <[email protected]> wrote: >> > > >> > >> Thanks, Gian, >> > >> >> > >> Your references are helpful and I am studying them. >> > >> >> > >> I didn't see any references to OpenJDK vs Oracle's JDKs. >> > >> >> > >> Are there any differences in the way Unsafe calls (or other hidden >> > >> classes) >> > >> are handled by OpenJDK? Or is this a "don't care" as far as Druid is >> > >> concerned? Are the version numbers between Oracle and OpenJDK always >> > >> aligned? >> > >> >> > >> >> > >> Lee. >> > >> >> > >> >> > >> >> > >> On Fri, Oct 11, 2019 at 5:45 PM Gian Merlino <[email protected]> >> wrote: >> > >> >> > >> > You didn't address this message to me, but in Druid most of the >> work >> > for >> > >> > Java 9+ compatibility is mentioned in this master issue, which you >> > might >> > >> > find helpful: >> https://github.com/apache/incubator-druid/issues/5589. >> > >> > Skimming the list, these might be particularly relevant to >> > DataSketches: >> > >> > >> > >> > - https://github.com/apache/incubator-druid/pull/7487 (cleaner >> > >> operations) >> > >> > - https://github.com/apache/incubator-druid/pull/7466 (ByteBuffer >> > unmap >> > >> > operation) >> > >> > - https://github.com/apache/incubator-druid/pull/7576 (Remove >> direct >> > >> > references to Unsafe) >> > >> > >> > >> > Btw, it would be better, I think, to address emails to the list at >> > >> large. >> > >> > It encourages more people to participate. If Roman is a subscriber >> he >> > >> would >> > >> > get a copy anyway. If not, you could encourage him to subscribe. >> > >> > >> > >> > On Fri, Oct 11, 2019 at 3:13 PM leerho <[email protected]> wrote: >> > >> > >> > >> > > Roman, >> > >> > > >> > >> > > I hope you are doing well. >> > >> > > >> > >> > > I really appreciate the contributions you made to our Memory >> > >> component! >> > >> > > >> > >> > > Given that Druid has made its code base compatible with OpenJDK >> 11, >> > we >> > >> > > could use your help in what changes do we need to make to make >> that >> > >> > happen >> > >> > > for DataSketches. As I recall, our DataSketches library was not >> the >> > >> only >> > >> > > Druid dependency that took advantage of Unsafe. So I assume you >> > have >> > >> > been >> > >> > > down this path :) >> > >> > > >> > >> > > Currently, I have a check in the static initializer in >> > >> Memory/UnsafeUtil: >> > >> > > parseJavaVersion(...) that checks the string returned from >> > >> > > System.getProperty("java.version"). If that string does not >> contain >> > >> > "1.8" >> > >> > > or "8" it will throw an error. Given that we have not tested >> with >> > >> JDK 9, >> > >> > > 10, 11 or 12, I felt it was safer to explicitly throw rather than >> > >> having >> > >> > > the users experience some weird failure later that may be >> difficult >> > to >> > >> > > debug. >> > >> > > >> > >> > > With only one minor exception (which we could easily fix) the >> Memory >> > >> > > component is the only place where Unsafe is used. However, we do >> > use >> > >> > > reflection to gain internal access to a number of other classes >> > >> including >> > >> > > ByteBuffer, Cleaner, and Bits. >> > >> > > >> > >> > > Looking forward to hearing from you. >> > >> > > >> > >> > > Cheers, >> > >> > > >> > >> > > Lee. >> > >> > > >> > >> > >> > >> >> > > >> > >> >
