The Maven Integration for Eclipse plugin, a.k.a. m2e, released version 1.5.0 a few weeks ago, as part of the annual Eclipse release train, this year known as Luna. 77 Bugs were fixed as part of that release, compatible with both Eclipse Kepler and Luna. I believe it’s a pretty solid one, with numerous interesting fixes and usability improvements that deserve a blog post. So here goes, in no particular order:
Improved project import workflow
Selecting Maven projects to import used to take an inordinate amount of time, due to a suboptimal - I love that word :-) - Maven Lifecycle Mapping Analysis (LMA). LMA is used to determine whether the projects would require further configuration to operate properly in Eclipse. That LMA is now only run after projects are imported, making selection of projects to import much, much faster (< couple seconds vs 1-2 min for the wildfly 8.0 codebase and its 130 projects, for instance)
After import, lifecycle mapping error markers are collected on imported projects and the discovery service is invoked to find proposals to fix those errors.
Another improvement to this workflow is the ability to easily import multi-module projects to an Eclipse Working Set. The default name is inferred from the root project but can be overridden manually:
More performance improvements during import itself are to be expected to be included in m2e 1.6.0.
Improved memory consumption
Maven project instance caching strategy has been revisited to reduce memory consumption. For a workspace with 300+ projects for instance, heap memory used went from 2.5GB down to well under 1GB without any noticeable side effects.
See Igor’s announcement and bug 410954.
Nexus index download disabled by default
Before m2e 1.5, by default, Nexus indexes were downloaded on new workspace startup, then subsequently once a week. Depending on your internet connection, that whole process could take 15 minutes or more, heavily pegging the CPU. Once the indexes were updated, the size of the workspace would increase by approximately 500 MB. Even though space is relatively cheap these days, those with many workspaces (eg., for testing) or large workspaces, this extra disk usage can add up quickly.
m2e 1.5.0 now has this feature disabled by default. You can still enable it in. One major downside of having this feature disabled by default though, is Archetype and Artifact/Plugin searches are now much less efficient, as they rely on this indexed content.
See bug 404417
New Maven Profile management UI
The JBoss Tools team contributed its Maven Profile management interface to m2e 1.5.0. This new interface eases switching between profiles.
Rather than right-clicking on a project, going to the Ctrl+Alt+P to open the new Maven Profile selection interface.page, then manually (mis)typing a list of active or disabled profiles, you can now just use
The new interface is also accessible from the Maven context menu: Right-click project
The list of available profiles is inferred from profiles defined in:
the project pom.xml
the project’s parent hierarchy
user and global maven settings.xml
When several projects are selected, only the common available profiles are displayed for selection. Common profiles are profiles defined in settings.xml or profiles having the same id in different pom.xml.
You can learn more about that feature from the original JBoss Tools blog
See bug 428094
Easily update outdated projects
The Update Maven Project dialog (launched via Right-click projector via Alt-F5), now shows a dirty overlay on projects which need updating.
Additionally, an "Add out-of-date" button adds all out-of-date (OOD) projects to the current selection. If an OOD project has not been selected, a warning is shown underneath the selection table with a link equivalent to "Add out-of-date". Warning text and "Add out-of-date" button tooltip show a count of unselected OOD projects.
See it in action: http://screencast.com/t/27S0qeca
See bug 422667
Unsupported IClasspathEntry kind=4
There’s a very popular question on StackOverflow about an
m2e bug that plagued many users of the maven-eclipse-plugin: m2e would throw
Unsupported IClasspathEntry kind=4 exceptions on classpath entries generated by the maven-eclipse-plugin
(one of the reasons why you should never mix maven-eclipse-plugin and m2e).
m2e 1.5.0 no longer complains about these unsupported classpath entries, but unexpected classpath issues may still arise, should you mix duplicate jars from m2e and those added by the maven-dependency-plugin.
See bug https://bugs.eclipse.org/394042
New checksum settings
Ever connected to a network with limited Internet access or simply stayed at a hotel where you needed to get past a for-pay-firewall, resulting in HTML pages being downloaded instead of jars? There’s nothing better to pollute your local Maven repository. Maven CLI builds can use these flags:
-C- fail build if checksums do not match
-c- warn if checksums do not match
m2e now has a global Checksum Policy available in, that will help you keep your sanity, and yor local repository clean:
While m2e actually won’t create any Warning markers on projects when "Warn" is selected, it will override existing checksum policies set on repositories.
See bug https://bugs.eclipse.org/418674
Improved settings for Errors/Warnings preferences
m2e has been known for generating specific errors that have puzzled more than one user in the past:
Project Configuration is not up-to-date- a change in pom.xml might require a full project configuration update.
Plugin execution not covered by lifecycle- m2e doe not know if it is safe to execute a maven plugin as part of the Eclipse build
With the new
Warning, or even be ignored entirely.
Maven runtime changes
A few changes have been made with regards to the Maven runtime(s):
The embedded Maven runtime has been updated to maven 3.2.1.
The Netty/AsynHttpClient transport layer as been replaced with OkHttp 1.5.4. OkHttp is now the default HTTP client on the Android platform. It brings HTTP 2.0 and SPDY support to artifact downloads. Please note though, NTLM authentication is not supported.
Maven runtime installations can now be customized with a name, and additional libraries can be added. Maven Launch configurations now reference the Maven runtime by name, instead of using a hard-coded location so the configuration is more portable.
Accept contributions from Gerrit
In order to lower the contribution barrier and increase contributor diversity, the m2e project now accepts changes contributed via the Gerrit review system. Head over the wiki that explains how to use it. Does it work? Hell yeah! After several significant contributions, Anton Tanasenko has joined the m2e team as commiter!
See bug 374665
With new blood on the m2e team, numerous fixed bugs and some big new features & improvements, m2e 1.5.0 is a pretty exciting release. Hope you guys appreciate this year’s release, before an even better version next time.
So if you haven’t installed m2e 1.5.0 yet, head over to https://www.eclipse.org/m2e/download/ and have at it.
We’d love to hear your feedback on the mailing list, or whether you report bugs or enhancement requests.