sbt/main-command/src
Ethan Atkins f1698d2bf2 Re-use metabuild scala instance layer
At some point I noticed that projects with no scala sources in the build
loaded significantly faster than projects that had even a single scala
file -- no matter how simple that file was. This didn't really make
sense to me because *.sbt files _do_ have to be compiled. I finally
realized that classloading was a likely bottle neck because *.sbt
files are compiled on the sbt classpath while *.scala files are compiled
with a different classloader generated by the classloader cache. It then
occurred to me that we could pre-fill the classloader cache with the
scala layer of the sbt metabuild classloader.

I found that compared to 1.3.0-M5, a project with a simple scala file in
the project directory loaded about 2 seconds faster after this change.
Even if there are no scala sources in the build.sbt, there is a similar
performance improvement for running "sbt compile", which I found exited
2-3 seconds faster after this change.
2019-06-06 21:02:24 -07:00
..
main Re-use metabuild scala instance layer 2019-06-06 21:02:24 -07:00
test/scala/sbt Don't check parents in ClassLoaderCacheTest 2019-05-28 11:53:13 -07:00