Fast JVM launching without the hassle of persistent JVMs.
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README.md

Drip is a launcher for the Java Virtual Machine that provides much faster startup times than the java command. The drip script is intended to be a drop-in replacement for the java command, only faster.

Drip is a single bash script and a small amount of Java code. It is intended to work with any JVM-based language and anywhere bash is available.

How does it work?

Unlike other tools intended to solve the JVM startup problem (e.g. Nailgun, cake, jark), Drip does not use a persistent JVM. There are many pitfalls to using a persistent JVM, which we discovered while working on the cake build tool for Clojure. The main problem is that the state of the persistent JVM gets dirty over time, producing strange errors and requiring liberal use of cake kill whenever any error is encountered, just in case dirty state is the cause.

Instead of going down this perilous road again, Drip uses a different strategy. It keeps a fresh JVM spun up in reserve with the correct classpath and other JVM options so you can quickly connect and use it when needed.

Installation

The following instructions assume that ~/bin is on your $PATH. If that is not the case, you can substitute your favorite location.

StandaloneWe recommend this to get started quickly.

curl -L http://drip.flatland.org > ~/bin/drip
chmod 755 ~/bin/drip

CheckoutIf you want to hack on Drip or follow the latest development, this is the way to go.

git clone https://github.com/flatland/drip.git
cd drip && make PREFIX=~/bin install

Usage

You can call drip with the same arguments as java. Try it. The first time you execute drip with new arguments, it will take longer, because it has to spin up a JVM from scratch, but after that it will be fast.

For example, to start a Clojure repl with drip:

drip -cp clojure.jar clojure.main

The Drip JVM will eventually shut itself down if you never connect to it. The time limit defaults to four hours, but you can change this by setting the DRIP_SHUTDOWN environment variable before calling drip to set a timeout, in minutes:

DRIP_TIMEOUT=30 drip -cp clojure.jar clojure.main

This creates a Clojure repl as usual, either by starting up a new one or connecting to a waiting JVM. But the JVM that is spun up to serve future requests with the same classpath will have a 30-minute timeout to deactivation.

JVM Language Integration

For more information about how to integrate Drip with your favorite JVM language, check out the JVM Language Integration page on the wiki.