`mvnd` - the Maven Daemon

This project aims at providing faster Maven builds using techniques known from Gradle and Takari.

Architecture overview:

mvnd embeds Maven (so there is no need to install Maven separately).
The actual builds happen inside a long living background process, a.k.a. daemon.
One daemon instance can serve multiple consecutive requests from the mvnd client.
The mvnd client is a native executable built using GraalVM. It starts faster and uses less memory compared to starting a traditional JVM.
Multiple daemons can be spawned in parallel if there is no idle daemon to serve a build request.

This architecture brings the following advantages:

The JVM for running the actual builds does not need to get started anew for each build.
The classloaders holding classes of Maven plugins are cached over multiple builds. The plugin jars are thus read and parsed just once. SNAPSHOT versions of Maven plugins are not cached.
The native code produced by the Just-In-Time (JIT) compiler inside the JVM is kept too. Compared to stock Maven, less time is spent by the JIT compilation. During the repeated builds the JIT-optimized code is available immediately. This applies not only to the code coming from Maven plugins and Maven Core, but also to all code coming from the JDK itself.

Additional features

mvnd brings the following features on top of the stock Maven:

-T1C is used by default. This means builing in parallel using as many threads as CPU cores on your machine. If your source tree does not support parallel builds, pass -T1 on the command line to make your build serial.
Improved console output: we believe that the output of a parallel build on a stock Maven is hard to follow. Therefore, we implemented a simplified a non-rolling view showing the status of each build thread on a separate line. This is what it looks like on a machine with 24 cores:

Once the build is finshed, the complete Maven output is forwarded to the console.

How to install `mvnd`

Install using SDKMAN!

If SDKMAN! supports your operating system, it is as easy as

$ sdk install mvnd

If you used the manual install in the past, please make sure that the settings in ~/.m2/mvnd.properties still make sense. With SDKMAN!, the ~/.m2/mvnd.properties file is typically not needed at all, because both JAVA_HOME and MVND_HOME are managed by SDKMAN!.

Install manually

Download the latest ZIP suitable for your platform from https://github.com/mvndaemon/mvnd/releases
Unzip to a directory of your choice
Add the bin directory to PATH
Optionally, you can create ~/.m2/mvnd.properties and set the java.home property in case you do not want to bother with setting JAVA_HOME environment variable.

Test whether mvnd works:

$ mvnd --version
Maven Daemon 0.0.0 (native)
Apache Maven 3.6.3 (cecedd343002696d0abb50b32b541b8a6ba2883f)
Maven home: /home/ppalaga/orgs/mvnd/mvnd/daemon/target/maven-distro
Java version: 11.0.1, vendor: AdoptOpenJDK, runtime: /home/data/jvm/adopt-openjdk/jdk-11.0.1+13
Default locale: en_IE, platform encoding: UTF-8
OS name: "linux", version: "5.6.13-200.fc31.x86_64", arch: "amd64", family: "unix"

If you are on Windows and see a message that VCRUNTIME140.dll was not found, you need to install vc_redist.x64.exe from https://support.microsoft.com/en-us/help/2977003/the-latest-supported-visual-c-downloads. See oracle/graal#1762 for more information.

Usage

mvnd is designed to accept the same command line options like stock mvn (plus some extras - see below), e.g.:

mvnd clean install

`mvnd` specific options

--status lists running daemons

--stop kills all running daemons

Build `mvnd` from source

Prerequisites:

git
Maven
Download and unpack GraalVM CE from GitHub

Set JAVA_HOME to where you unpacked GraalVM in the previous step. Check that java -version output is as expected:

$ $JAVA_HOME/bin/java -version
openjdk version "11.0.7" 2020-04-14
OpenJDK Runtime Environment GraalVM CE 20.1.0 (build 11.0.7+10-jvmci-20.1-b02)
OpenJDK 64-Bit Server VM GraalVM CE 20.1.0 (build 11.0.7+10-jvmci-20.1-b02, mixed mode, sharing)

Install the native-image tool:

$ $JAVA_HOME/bin/gu install native-image

native-image may require additional software to be installed depending on your platform - see the native-image documentation.

Build `mvnd`

$ git clone https://github.com/mvndaemon/mvnd.git
$ cd mvnd
$ mvn clean verify -Pnative
...
$ cd client
$ file target/mvnd
target/mvnd: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, BuildID[sha1]=93a554f3807550a13c986d2af9a311ef299bdc5a, for GNU/Linux 3.2.0, with debug_info, not stripped
$ ls -lh target/mvnd
-rwxrwxr-x. 1 ppalaga ppalaga 25M Jun  2 13:23 target/mvnd

This project is still in prototype mode, so feedback is most welcomed!

ybroeker/mvnd

mvnd - the Maven Daemon