I believe mr-jar build is enabled in the 8x branch (LUCENE-7966), and the workaround was dropped on the master branch when the minimum java version was bumped up to java 11 (LUCENE-8738); if my understanding is correct.
$ jar tf core/lucene-core-8.6.1.jar | grep META-INF/versions META-INF/versions/ META-INF/versions/9/ META-INF/versions/9/org/ META-INF/versions/9/org/apache/ ... $ jar tf core/build/libs/lucene-core-9.0.0-SNAPSHOT.jar | grep META-INF/versions // no outputs 2020年8月30日(日) 6:48 Mike Drob <md...@apache.org>: > Do you know if these mr-jars are built by default as part of the release > process? I definitely had no idea about them when doing 8.5.2 and did not > even think to verify anything about it. > > On Sat, Aug 29, 2020 at 4:05 PM Adrien Grand <jpou...@gmail.com> wrote: > >> It may only be indirectly related to your question, but there is support >> for vectorized operations of byte[] arrays that was added in JDK 13 (this >> blog https://richardstartin.github.io/posts/vectorised-byte-operations >> explains >> well what it is about) that we started leveraging for compressing terms >> dictionaries in Lucene 8.5: >> https://issues.apache.org/jira/browse/LUCENE-4702. >> >> I don't know how well this is known but our build also has logic to >> create multi-release JARs. We don't use it in master today but it's used on >> branch_8x, which requires Java 8, in order to use APIs that were introduced >> in Java 9 such as Arrays#mismatch. See the "patch-mr-jar" target in the >> branch_8x build: >> https://github.com/apache/lucene-solr/blob/branch_8x/lucene/common-build.xml#L602. >> So if APIs that could help performance were introduced in say JDK 15, we >> might still be able to leverage them in Lucene/Solr 9 using the same >> mechanism. >> >> >> >> On Tue, Aug 11, 2020 at 1:12 AM Marcus Eagan <marcusea...@gmail.com> >> wrote: >> >>> In my IDE, I have a few profiling tools that I bounce between that I >>> started using in my work at Lucidworks but I continue to use in my current >>> work today. I have suspicions that there may be some performance >>> improvements in Java 11 that we can exploit further. I'm curious as to if >>> there has been any investigation, possibly Mark Miller or >>> @u...@thetaphi.de <u...@thetaphi.de>, into performance improvements >>> specific to the newer version of Java in Master? There are some obvious >>> ones that we get for free, like a better GC, but curious as to prior work >>> in this area before publishing anything that might be redundant or >>> irrelevant. >>> >>> Best, >>> >>> -- >>> Marcus Eagan >>> >>> >>> >>> >> >> -- >> Adrien >> >> >>
