AspectJ 1.9.21

The releases 1.9.21, 1.9.21.1 and 1.9.21.2 are described together in this document.

AspectJ 1.9.21.2

Release info: 1.9.21.2 available 13-Mar-2024

Please note that Bugzilla for issue management is deprecated and new issues should be filed as GitHub issues. The list of issues addressed for 1.9.21.2 can be found here:

New features

AspectJ 1.9.21.2 is a maintenance release with no new language features, but an important improvement and a bugfix, see below.

Improvements

Previously, when targeting the same join point from multiple around advices in annotation-style @AspectJ syntax, there were limitations in functionality in concurrent (multi-threaded) situations, if the around advice code was not inlined. This was improved in AspectJ 1.9.9 (see also issue #128), but the improvement only applied to child threads directly created during aspect execution and would fail for pre-existing, long-lived threads, e.g. thread pools used by executor services. Furthermore, the improvement could lead to memory leaks, not cleaning up thread-local references to posssibly expensive objects. In such situations, users had to switch to native-syntax aspects which never had that problem to begin with due to their different internal structure.

Now, issue #141 has been resolved, closing the gap and, as well as possible given their different internal structure, bringing @AspectJ aspects up to par with native-syntax aspects in concurrent situations, while simultaneously also addressing the memory leak issue #288. This is a substantial improvement, and annotation-style syntax users are strongly engouraged to upgrade. Thanks to user pagrawalgit for raising the memory leak issue and triggering me to think about the concurrency issue more broadly and finally solve both in one shot.

Other changes and bugfixes

The fix for issue #277 in AspectJ 1.9.21.1 introduced a regression bug in the optional weaving cache now fixed in issue #285. Thanks to user Kimming Lau for raising and re-testing both issues.

AspectJ 1.9.21.1

Release info: 1.9.21.1 available 14-Feb-2024

Please note that Bugzilla for issue management is deprecated and new issues should be filed as GitHub issues. The list of issues addressed for 1.9.21.1 can be found here:

New features

AspectJ 1.9.21.1 is a maintenance release with no new language features, but important improvements and some bugfixes, see below.

Improvements

For load-time weaving (LTW) on JDK 16+, using --add-opens is no longer necessary! This solves issue #117. The additional JVM command-line option was necessary for LTW on JRE 16+ in all AspectJ versions up to 1.9.21. Since AspectJ 1.9.21.1, the LTW agent uses an alternative approach for defining new classes during weaving, which works without --add-opens - at least for now, i.e. JDKs 8 to 21. There still is no canonical solution, because JDK-8200559 is still unresolved since 2018.
The AspectJ documentation is now written in asciidoc format and processed by the Asciidoctor toolchain. Before, it was a mixture of DocBook XML and plain HTML files. While the content has not changed much, it now looks fresher, is easier to read (also online when browsing the GitHub repository), navigate and maintain and also easy to publish in different formats (multi-page HTML, single-page HTML, PDF). Those formats are also distributed on the website and with the AspectJ installer. A content overhaul is also overdue, but not part of this change. It is still basically the same: Everything up to AspectJ 1.5 is in the regular documentation. The changes since then can be extracted incrementally from various release notes.

Other changes and bugfixes

Running the AspectJ Compiler on JDK < 17 no longer creates an ajcore.*.txt crash dump file, but prints "The AspectJ compiler needs at least Java runtime 17". Fixes issue #269.
The AspectJ weaver now plays nicer with parallel class loaders, e.g. jboss-modules in WildFly. Before, it would sometimes return original instead of woven byte code. Fixes issue #279.
An upstream refresh from JDT Core (Eclipse Java Compiler) fixes a little bug in JDK 21 string templates.

AspectJ 1.9.21

Release info: 1.9.21 available 11-Dec-2023

Please note that Bugzilla for issue management is deprecated and new issues should be filed as GitHub issues. The list of issues addressed for 1.9.21 can be found here:

New features

AspectJ 1.9.21 supports Java 21, its final features and a subset of preview features, such as:

Record patterns
Pattern matching for switch
Virtual threads
Sequenced collections
Structured concurrency (preview)
String templates (preview)
Instance main methods (preview)

Unfortunately, even after holding back the AspectJ release for 3 months after JDK 21 general availability, waiting for Eclipse JDT Core and the Eclipse Java Compiler (ECJ) to catch up with Java 21 language features, even with Java 21 officially supported in Eclipse 2023-12, some preview features are still unimplemented in ECJ:

Unnamed classes (preview)
Unnamed patterns and variables (preview)

As soon as these preview features are part of the upstream ECJ we depend on, we hope to publish another AspectJ release to support them in the AspectJ Compiler (AJC), too.

Improvements

In GitHub issue 266, exception cause reporting has been improved in ExtensibleURLClassLoader. Thanks to Andy Russell (@euclio) for his contribution.

Other changes and bug fixes

No major bug fixes

AspectJ usage hints

AspectJ compiler build system requirements

Since 1.9.21, the AspectJ compiler ajc (contained in the aspectjtools library) no longer works on JDKs 11 to 16. The minimum compile-time requirement is now JDK 17 due to upstream changes in the Eclipse Java Compiler (subset of JDT Core), which AspectJ is a fork of. You can still compile to legacy target versions as low as Java 1.3 when compiling plain Java code or using plain Java ITD constructs which do not require the AspectJ runtime aspectjrt, but the compiler itself needs JDK 17+. Just like in previous AspectJ versions, both the runtime aspectjrt and the load-time weaver aspectjweaver still only require JRE 8+.

Please note: If you run ajc on JDKs 11-16, you will probably see an error like java.lang.NoSuchFieldError: RELEASE_17, and an ajcore.*.txt dump file will be created, while running it on even older JDKs will rather yield an UnsupportedClassVersionError. See GitHub issue 269 for more details.

History: Since 1.9.8, the AspectJ compiler ajc needed JDK 11+, before then JDK 8+.

Use LTW on Java 16+

Please note that if you want to use load-time weaving on Java 16+, the weaving agent collides with JEP 396 (Strongly Encapsulate JDK Internals by Default) and related subsequent JEPs. Therefore, you need to set the JVM parameter --add-opens java.base/java.lang=ALL-UNNAMED in order to enable aspect weaving. This is due to the fact that the weaver uses internal APIs for which we have not found an adequate replacement yet when defining classes in different classloaders.

Update: As of AspectJ 1.9.21.1, --add-opens is no longer necessary. Please upgrade, if it bothers you too much.

Compile with Java preview features

For features marked as preview on a given JDK, you need to compile with ajc --enable-preview and run with java --enable-preview on that JDK.

Please note, that you cannot run code compiled with preview features on any other JDK than the one used for compilation. For example, records compiled with preview on JDK 15 cannot be used on JDK 16 without recompilation. This is a JVM limitation unrelated to AspectJ. Also, e.g. sealed classes are preview-1 on JDK 15 and preview-2 on JDK 16. You still need to recompile, no matter what.