Making a splash

One To Watch: Drip – a speedier launcher for the JVM

Elliot Bentley

We speak to the developer behind a new tool which takes a brutally simple approach to reducing JVM startup time from the command line.

Last week, we couldn’t help but notice the buzz on Twitter
surrounding a young github project called Drip, designed to launch the
JVM faster than the standard java command.

Our curiosity piqued, we got in touch with one of Drip’s
developers, Justin Balthrop, to find out more about the project.
“We started coding drip less than a week ago,” he told JAXenter.
“So it is definitely still alpha. I didn’t expect it to take off
like this.”

The project was borne out of frustration with the slowness
of  of Java command line tools. Their first attempt was
the Clojure build tool Cake, which utilised a persistent
JVM, but it was a “huge mistake”, says Balthrop. “Once we saw
the speed, we were hooked and couldn’t give it up, but keeping the
state correct in a running JVM when code is changing is incredibly

“We wasted a lot of time making it pretty good, but the problem is
you never really trust the persistent JVM. Your first reaction when
something isn’t working right is still to restart the entire JVM,
just in case.”

So to solve this, Drip rapidly boots up (and then disposes of) JVMs
– a simple but effective solution with the added benefit of working
across languages. So far, the team have tested it with Java,
Clojure, JRuby and Scala.

For something so basic, what is it about Drip that has attracted so
much attention? Balthrop has a theory.

“I think there are a lot of people out there who want to develop
for the JVM on the command line, not in a specialized IDE. With the
rise of languages like Clojure and Scala, that number is only
increasing. When you’re writing software rather that just using it,
you need a very short edit-compile-test cycle, and Java’s slow
startup time can get frustrating.”

Drip was released by a group called Flatland, whose website lists little more than its
members names. It’s less of an organisation, more a communal label
to put projects by
employees under.

“I can’t explain why, but personally I’m just more inclined to use
and get excited about a project that isn’t an advertisement for the
company that created it,” he says. “Hopefully, flatland will be a
group of coders that grows over time and continues throughout our

The Flatland github
already has 30 public repos, the majority involving
Clojure. Drip development is still ongoing, though, with new
features still to come.

“The most important feature is getting Drip to work correctly with
JLine,” says Balthrop. “We just released the ability to run
initialization code when starting the JVM. This can increase speed
a lot by loading classes or compiling Clojure code ahead of time.
Of course, you have to be careful not to pre-load code that will
change, but this can work well for build tools, because they have a
lot of classes that don’t change.

“We’d also like to add a hook so you can tell Drip how to check if
the JVM is stale before accepting a connection,” he adds.

So, considering the attention Drip has garnered for simply reducing
JVM startup times, does Balthrop reckon there’s any chance of
Oracle upping their game and making the ‘java’ command

“That’d be awesome, but I think we’d need a million more people
using Drip before Oracle would take notice,” he says. “One can
always hope though.”

You can download the Drip source from its github repo.

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