On Tue, Feb 05, 2019 at 11:42:32PM -0600, Alex Miller wrote: > > Some things I would look at: > > - Try with -Dclojure.spec.skip-macros=true to see if any difference > (skips spec macro checking which could possibly affect startup time)
Is this a runtime or build arugment? I can't find this documented anywhere except in this commit[0]. [0]: https://github.com/clojure/clojure/commit/3d9b356306db77946bdf4809baeb660f94cec846 > - Check that you're actually using AOT'ed Clojure. In the clojure jar > file, typically you'll see both .class and .clj files. The timestamps > matter! If the .clj is newer than the .class files, it will use the > .clj and recompile. I have certainly seen people run into this kind of > problem with builds that don't retain timestamps properly for whatever > reason (the Maven shade plugin is a notorious culprit, but we don't > use that in the Clojure build). So I think I found one fishy looking thing: while clojure.jar's timestamps are all fine, it appears that the core.specs.alpha and spec.alpha jars have .clj files with identical timestamps to the source files, which may be affecting things. Ditto clojure1.8, etc. I believe this is due to Debian's reproducible build steps. However, that doesn't explain the massive slowdown between JDK8 and JDK11 for all Clojure jars, 1.8 included. elana@debian:/debian/clojure$ time /usr/lib/jvm/java-8-openjdk-amd64/bin/java -cp /usr/share/java/clojure-1.8.jar clojure.main -e '"hi"' "hi" real 0m4.368s user 0m13.633s sys 0m0.360s elana@debian:/debian/clojure$ time /usr/lib/jvm/java-8-openjdk-amd64/bin/java -cp /usr/share/java/clojure-1.8.jar clojure.main -e '"hi"' "hi" real 0m3.941s user 0m13.516s sys 0m0.356s elana@debian:/debian/clojure$ time /usr/lib/jvm/java-11-openjdk-amd64/bin/java -cp /usr/share/java/clojure-1.8.jar clojure.main -e '"hi"' "hi" real 0m9.962s user 0m24.804s sys 0m0.507s elana@debian:/debian/clojure$ time /usr/lib/jvm/java-11-openjdk-amd64/bin/java -cp /usr/share/java/clojure-1.8.jar clojure.main -e '"hi"' "hi" real 0m10.040s user 0m26.233s sys 0m0.586s I'm finding this utterly baffling. For comparison, on the same machine I downloaded the official 1.8 release, and it's not seeing the same performance issues: elana@debian:/tmp$ time /usr/lib/jvm/java-11-openjdk-amd64/bin/java -cp clojure-1.8.0.jar clojure.main -e '"hi"' "hi" real 0m1.377s user 0m2.652s sys 0m0.155s elana@debian:/tmp$ time /usr/lib/jvm/java-8-openjdk-amd64/bin/java -cp clojure-1.8.0.jar clojure.main -e '"hi"' "hi" real 0m1.232s user 0m2.048s sys 0m0.124s Another data point: clj 1.10 linked with the Debian core.specs.alpha and spec.alpha: elana@debian:/tmp$ time /usr/lib/jvm/java-8-openjdk-amd64/bin/java -cp clojure-1.10.0.jar:/usr/share/maven-repo/org/clojure/spec.alpha/debian/spec.alpha-debian.jar:/usr/share/maven-repo/org/clojure/core.specs.alpha/debian/core.specs.alpha-debian.jar clojure.main -e '"hi"' "hi" real 0m2.761s user 0m7.836s sys 0m0.317s elana@debian:/tmp$ time /usr/lib/jvm/java-11-openjdk-amd64/bin/java -cp clojure-1.10.0.jar:/usr/share/maven-repo/org/clojure/spec.alpha/debian/spec.alpha-debian.jar:/usr/share/maven-repo/org/clojure/core.specs.alpha/debian/core.specs.alpha-debian.jar clojure.main -e '"hi"' "hi" real 0m4.363s user 0m14.337s sys 0m0.381s vs. upstream specs, which it is faster with: elana@debian:/tmp$ time /usr/lib/jvm/java-11-openjdk-amd64/bin/java -cp clojure-1.10.0.jar:core.specs.alpha-0.2.44.jar:spec.alpha-0.2.176.jar clojure.main -e '"hi"' "hi" real 0m1.688s user 0m3.741s sys 0m0.173s elana@debian:/tmp$ time /usr/lib/jvm/java-8-openjdk-amd64/bin/java -cp clojure-1.10.0.jar:core.specs.alpha-0.2.44.jar:spec.alpha-0.2.176.jar clojure.main -e '"hi"' "hi" real 0m1.446s user 0m2.752s sys 0m0.166s This strongly suggests to me that something different happening in the Debian build process is causing a performance degradation. Debian's up-to-date core.specs.alpha and spec.alpha are in the archive, but in case anyone wants to poke around with the guts of the jars I built/are installed in the archive[1]. Note that the terrible performance times I'm seeing here look similar to what Rob reported when we had an issue with reproducible builds affecting Clojure performance[2]. - e [1]: https://csclub.uwaterloo.ca/~ehashman/debian/clojure/ [2]: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=877418
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