JMH benchmarks for the Scala Compiler

Goal: define a set of JMH benchmarks for the compiler to help drive performance tuning and catch performance regressions.

Based on:

OpenJDK JMH, the definitive Java benchmarking tool.
via sbt-jmh.

Structure

Project	Benchmark of
compilation	The equivalent of `scalac ...`
micro	Finer grained parts of the compiler
jvm	Pure Java benchmarks to demonstrate JVM quirks
infrastructure	Code to persist benchmark results and metadata

Recipes

Learning about JMH options

sbt> compilation/jmh:run -help

Benchmarking compiler performance

(optional) add new Scala sources (say aardvark) to a new directory in src/main/corpus

compilation/jmh:run (Cold|Warm|Hot)CompilationBenchmark 
   -p source=(<subdir of corpus>|/path/to/src/dir|@/path/to/argsfile)
   -p extraArgs=-nowarn

Using aliases

Avoid the tedium of typing all that out with:

sbt> hot -psource=scalap 
sbt> cold -psource=better-files

Changing Scala Version

sbt> set scalaVersion in ThisBuild := "2.12.0-ab61fed-SNAPSHOT"
sbt> set scalaHome in ThisBuild := Some(file("/code/scala/build/pack"))
sbt> set scalaHome in compilation := "2.11.1" // if micro project isn't compatible with "2.11.1"

Persisting results

Provide INFLUX_PASSWORD as an environment variable
Replace jmh/run with jmh:runMain scala.bench.UploadingRunner

Results will be uploading into an [InfluxDB]() instance at https://scala-ci.typesafe.com/influx/

These results will be plotted in our Grafana dashboard

Note that the https://github.com/scala/compiler-benchq project, which will trigger benchmarks for merges and sets of commits that we're backtesting.

Collecting profiling data

sbt> .../jmh:run Benchmark -prof jmh.extras.JFR // Java Flight Recorder

Using Graal

Install Graal VM and JDK8 with JVMCI.

compilation/jmh:run CompileSourcesBenchmark 
    -jvm      /path/to/labsjdk1.8.0_92-jvmci-0.20/bin/java
    -jvmArgs -XX:+UnlockExperimentalVMOptions
    -jvmArgs -XX:+EnableJVMCI
    -jvmArgs -Djvmci.class.path.append=/path/to/graalvm-0.15-re/lib/jvmci/graal.jar
    -jvmArgs -Xbootclasspath/a:/path/to/graalvm-0.15-re/lib/truffle-api.jar
    -jvmArgs -Djvmci.Compiler=graal 
    -jvmArgs -XX:+UseJVMCICompiler

Exporting an args file from SBT

$ curl https://gist.githubusercontent.com/retronym/78d016a3f10c62da2fd47cacac867f25/raw/65d9a1e8458d5984784ecf411d6c4d257bfdf0c1/ArgsFile.scala >  ~/.sbt/0.13/plugins/ArgsFile.scala
$ cd /code/someProject
$ sbt core/compile:argsFilePrint
[info] Set current project to root (in build file:/Users/jason/code/better-files/)
-deprecation
-encoding
UTF-8
-feature
-language:implicitConversions
-language:reflectiveCalls
-unchecked
-Xfatal-warnings
-Xlint
-Yinline-warnings
-Yno-adapted-args
-Ywarn-dead-code
-Xfuture
/Users/jason/code/better-files/core/src/main/scala/better/files/Cmds.scala
/Users/jason/code/better-files/core/src/main/scala/better/files/File.scala
/Users/jason/code/better-files/core/src/main/scala/better/files/Implicits.scala
/Users/jason/code/better-files/core/src/main/scala/better/files/package.scala
/Users/jason/code/better-files/core/src/main/scala/better/files/Scanner.scala
/Users/jason/code/better-files/core/src/main/scala/better/files/ThreadBackedFileMonitor.scala
[success] Total time: 0 s, completed 02/09/2016 11:51:58 AM

Place this output into a file. The full path to that file can be passed to the -source= option to run the benchmark on that project: -psource=@/path/to/args/file

lampepfl / compiler-benchmark

readme