==Introduction
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.
mvnd
brings the following features on top of the stock Maven:
-
By default,
mvnd
is building your modules in parallel using multiple CPU cores. The number of utilized cores is given by the formulaMath.max(Runtime.getRuntime().availableProcessors() - 1, 1)
. If your source tree does not support parallel builds, pass-T1
into the command line to make your build serial. -
Improved console output: we believe that the output of a parallel build on stock Maven is hard to follow. Therefore, we implemented a simplified 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 finished, the complete Maven output is forwarded to the console.
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 using Homebrew
$ brew install mvndaemon/homebrew-mvnd/mvnd
We’re looking for contribution to support MacPorts, Chocolatey, Scoop or asdf. If you fancy helping us…
Optionally, you can set up completion as follows:
# ensure that MVND_HOME points to your mvnd distribution, note that sdkman does it for you
$ echo 'source $MVND_HOME/bin/mvnd-bash-completion.bash' >> ~/.bashrc
bash
is the only shell supported at this time.
Users that use oh-my-zsh
often use completion for maven. The default maven completion plugin defines mvnd
as an alias to mvn deploy
. So before being able to use mvnd
, you need to unalias using the following command:
$ unalias mvnd
-
Download the latest ZIP suitable for your platform from https://downloads.apache.org/maven/mvnd/
-
Unzip to a directory of your choice
-
Add the
bin
directory toPATH
-
Optionally, you can create
~/.m2/mvnd.properties
and set thejava.home
property in case you do not want to bother with setting theJAVA_HOME
environment variable. -
Test whether
mvnd
works:$ mvnd --version Maven Daemon 0.0.11-linux-amd64 (native) Terminal: org.jline.terminal.impl.PosixSysTerminal with pty org.jline.terminal.impl.jansi.osx.OsXNativePty 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 installvc_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.If you are on macOS, you’ll need to remove the quarantine flags from all the files after unpacking the archive:
$ xattr -r -d com.apple.quarantine mvnd-x.y.z-darwin-amd64
mvnd
is designed to accept the same command line options like stock mvn
(plus some extras - see below), e.g.:
mvnd verify
--status
lists running daemons
--stop
kills all running daemons
mvnd --help
prints the complete list of options
Configuration can be provided through the properties file. Mvnd reads the properties file from the following locations:
-
the properties path supplied using
MVND_PROPERTIES_PATH
environment variable ormvnd.propertiesPath
system variable -
the local properties path located at
[PROJECT_HOME]/.mvn/mvnd.properties
-
the user properties path located at:
[USER_HOME]/.m2/mvnd.properties
-
the system properties path located at:
[MVND_HOME]/conf/mvnd.properties
Properties defined in the first files will take precedence over properties specified in a lower ranked file.
A few special properties do not follow the above mechanism:
-
mvnd.daemonStorage
: this property defines the location where mvnd stores its files (registry and daemon logs). This property can only be defined as a system property on the command line -
mvnd.id
: this property is used internally to identify the daemon being created -
mvnd.extClasspath
: internal option to specify the maven extension classpath -
mvnd.coreExtensions
: internal option to specify the list of maven extension to register
For a full list of available properties please see /dist/src/main/distro/conf/mvnd.properties.
-
git
-
Maven
-
Download and unpack GraalVM CE from GitHub
-
Set
JAVA_HOME
to where you unpacked GraalVM in the previous step. Check thatjava -version
output is as expected:$ $JAVA_HOME/bin/java -version openjdk version "11.0.9" 2020-10-20 OpenJDK Runtime Environment GraalVM CE 20.3.0 (build 11.0.9+10-jvmci-20.3-b06) OpenJDK 64-Bit Server VM GraalVM CE 20.3.0 (build 11.0.9+10-jvmci-20.3-b06, mixed mode, sharing)
-
Install the
native-image
tool:$ $JAVA_HOME/bin/gu install native-image
-
native-image
may require additional software to be installed depending on your platform - see thenative-image
documentation.
$ git clone https://github.com/apache/maven-mvnd.git
$ cd maven-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
Please note that if you are using Windows as your operating system you will need the following prerequisites for building maven-mvnd
:
a version of Visual Studio with the workload "Desktop development with C++" and the individual component "Windows Universal CRT SDK".
$ cp -R dist/target/mvnd-[version] [target-dir]
Then you can simply add [target-dir]/bin
to your PATH
and run mvnd
.
We’re happy to improve mvnd
, so feedback is most welcome!