Improving startup time of Clojure REPL with Leiningen on the Raspberry Pi

Question

I got a Rasperry Pi 512 MB version (late 2012) and installed the Developer Preview of Java SE 8 for ARM on it. When I create a new Clojure project with Leiningen and launch the nREPL by doing lein repl it takes a bit more than two minutes (roughly 130 - 140 seconds) until the REPL has been initialized and can be used.

When launching the JAR file directly java -jar clojure-1.4.0/clojure-1.4.0 the REPL starts up in 25s.

I'm using fast class 10 SD cards (SanDisk Extreme with up to 30 MB/s). How come that the difference between using Leiningen with nRepl vs launching the JAR file is so big? What could be done to improve the startup time with Leiningen for the Raspberry Pi?

Answer 1

Also try grenchman: Fast invocation of Clojure code over nREPL.

Answer 2

You can try drip which wraps the java command and prepare a fresh jvm waiting in the background.

Answer 3

It seems the slow startup of clojure in general is the loading of core and various other things discussed here:

http://blog.ndk.io/solving-clojure-boot-time.html

Answer 4

Actually the Leiningen starts in it's own JVM and then nests the project's vm inside it.
Then it checks deps, figures out the changes and so on.

You can avoid vm nesting with the trampoline task of lein like so:
lein trampoline repl

But this command requires the lein to be called in a project directory