Hi, We need to support Java8. +1 for reusing the constants in RamUsageEstimator
Jialin Qiao Yuan Tian <[email protected]> 于2024年1月5日周五 09:25写道： > > Hi Chris, > > I think I've got another way to do this, you can see in my pr( > https://github.com/apache/tsfile/pull/3). I found that all the constants > have already been calculated and defined in the `RamUsageEstimator` of > lucene and we can directly use that instead of defining it again. > > > Best regards, > -------------------------- > Yuan Tian > > On Thu, Jan 4, 2024 at 11:59 PM Christofer Dutz <[email protected]> > wrote: > > > Hi all, > > > > so today we stumbled over a new type of problem (and I thought I had seen > > all types). > > In order to replace the GPL licensed library, direct usages of > > sun.misc.Unsafe were added for getting the sizes of types and arrays in JMV > > memory. > > > > The main problem is: If we want to compile true Java 8 libraries with any > > java version greater than 8, we need to set the “release” config option in > > the maven plugin. This tells the compiler to cross compile for that java > > version. It does this by checking an index file for that given java > > version. Problem seems to be that for java 8 the sun.misc.Unsafe is not > > included in this index and the compiler therefore fails. > > > > Now there are multiple options to resolve this issue: > > > > We could not use the “release” option, but that could produce Jars that > > have the right java class version, but can’t work on Java 8 because of > > missing types. (Sub-Ideal) > > > > We could create a library, that wraps these calls and which is compiled on > > Java 8. So Instead of using the direct calls, we’d use that library > > instead. However this is just tricking the compiler and if in any future > > version of Java this file is moved/removed, things will explode. > > > > As a third option, I see that we could simply define the constants to > > fixed values. These values are really not going to change and I will do a > > check with what the values are on various JDKs and OSes. This option has > > the advantage, that if any of these values would change in future versions, > > the old data-files would not be corrupt. And if we want to Provide TsFiles > > on other systems than Java, we probably need constants anyway. > > > > I have therefore defined these constants in order to get the build working > > again and we’ll continue this discussion to which path we want to go. > > > > > > Chris > >
