Possible memory leak in Tasks.scala

I have a relatively large multimodule project (30+modules) which, thanks to hadoop, transitively depends on about half of maven-central.

When I perform project-wise operations like sbt update (or hitting Refresh Project in intelliJ), the JVM ends up in OutOfMemoryError (GC overhead limit exceeded). The same operation with coursier plugin disabled works fine (as long as wasting 10+ minutes can be considered as fine 😃 ).

Upon heap dump investigation (which is definitely not one of my strongest skills), it appears that the heap contains millions (40+) of HashMap entries, many of whose nearest GC-root seems to be the reportsCache created here.

The version used is 1.0.0-M14-9

Illustration : http://imgur.com/a/PS37A

[vil1]

I confirm, the memory problems seem to be fixed by #462 Thx a lot

[vil1]

I finally managed to work around the problem using the following JVM options for SBT :

-XX:+UseG1GC
-XX:MaxGCPauseMillis=200
-XX:ParallelGCThreads=4
-XX:ConcGCThreads=4
-XX:InitiatingHeapOccupancyPercent=50

(Thanks to @samklr’s advice)