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+== AspectJ 1.6.1
+
+_© Copyright 2008 Contributors. All rights reserved._
+
+The main themes of AspectJ1.6.1 are better memory usage and faster
+weaving. This has been achieved through profiling of the weaving process
+and has resulted in some serious refactoring of the weaver component
+within AspectJ. It provides exactly the same functionality as in
+previous releases, it just weaves faster now, using less code and less
+memory. This readme will give an overview of the kind of changes made
+and what can be expected when using 1.6.1 compared to previous releases.
+
+The complete list of issues resolved for AspectJ 1.6.1 can be found with
+these bugzilla queries. The first lists bugs addressed (more than 60!)
+whilst the second details enhancements made in this release.
+
+* https://bugs.eclipse.org/bugs/buglist.cgi?query_format=advanced&short_desc_type=allwordssubstr&short_desc=&product=AspectJ&target_milestone=1.6.1&long_desc_type=allwordssubstr&long_desc=&bug_file_loc_type=allwordssubstr&bug_file_loc=&status_whiteboard_type=allwordssubstr&status_whiteboard=&keywords_type=allwords&keywords=&bug_status=RESOLVED&bug_status=VERIFIED&bug_status=CLOSED&bug_severity=blocker&bug_severity=critical&bug_severity=major&bug_severity=normal&bug_severity=minor&bug_severity=trivial&emailtype1=substring&email1=&emailtype2=substring&email2=&bugidtype=include&bug_id=&votes=&chfieldfrom=&chfieldto=Now&chfieldvalue=&cmdtype=doit&order=Reuse+same+sort+as+last+time&field0-0-0=noop&type0-0-0=noop&value0-0-0=[Bugs
+resolved]
+* https://bugs.eclipse.org/bugs/buglist.cgi?query_format=advanced&short_desc_type=allwordssubstr&short_desc=&product=AspectJ&target_milestone=1.6.1&long_desc_type=allwordssubstr&long_desc=&bug_file_loc_type=allwordssubstr&bug_file_loc=&status_whiteboard_type=allwordssubstr&status_whiteboard=&keywords_type=allwords&keywords=&bug_status=RESOLVED&bug_status=VERIFIED&bug_status=CLOSED&bug_severity=enhancement&emailtype1=substring&email1=&emailtype2=substring&email2=&bugidtype=include&bug_id=&votes=&chfieldfrom=&chfieldto=Now&chfieldvalue=&cmdtype=doit&order=Reuse+same+sort+as+last+time&field0-0-0=noop&type0-0-0=noop&value0-0-0=[Enhancements
+implemented]
+
+'''''
+
+=== Refactored (https://bugs.eclipse.org/bugs/show_bug.cgi?id=231396[bug 231396])
+
+The bugzilla entry goes into more specifics on what has changed, the end
+result is that aspectjweaver.jar has had around 275 classes removed
+(about 25%) and has slimmed down by 350k (about 20%). In terms of
+performance for different scenarios:
+
+==== Straight compilation
+
+The refactoring effort has been focused on the weaver component, hence
+there is limited impact on the performance of source compilation but
+this comparison shows it is faster. Four scenarios are compared, in each
+scenario a different aspect is applied to the JDT compiler (just as a
+sample piece of source code).
+
+. 1100 source files, few aspects that target 859 join points.
+. 1100 source files, code style trace aspect targeting public methods
+(22000 join points)
+. 1100 source files, annotation style trace aspect (22000 join points)
+. 1100 source files, insane aspect (before(): within(*) \{}) (203000
+join points)
+
+image:perfSourceCompile_161.jpg[image]
+
+==== Binary weaving
+
+Moving on from source compilation to pure binary weaving, the
+improvements are more obvious. Here we are using the complete JVM
+classes jar 'rt.jar' as an example of a large jar file for weaving.
+
+. Binary weaving rt.jar (~12000 classes) with a simple aspect (1200 join
+points)
+. Binary weaving rt.jar (~12000 classes) with a code style trace aspect
+(121000 join points)
+. Binary weaving rt.jar (~12000 classes) with an annotation style trace
+aspect (121000 join points)
+. Binary weaving rt.jar (~12000 classes) with an insane aspect
+(before(): within(*) \{}) (352000 join points)
+
+image:perfBinaryWeave_161.jpg[image]
+
+==== Loadtime weaving
+
+The loadtime weaving improvements are similar to those seen for binary
+weaving (naturally). Here we are using the JDK tools jar 'tools.jar' as
+an example of a jar file for loadtime weaving.
+
+. Binary weaving tools.jar (~1900 classes) with a code style trace
+aspect
+. Binary weaving tools.jar (~1900 classes) with an insane aspect
+(before(): within(*) \{})
+
+image:perfLTW_161.jpg[image]
+
+The refactoring work has also reduced the amount of unnecessary garbage
+created on the heap during the weaving process. The next comparison
+shows roughly the reduction in amount of 'stuff' created on the heap
+during a weave. This isn't the max heap required to do a weave, it is
+just showing how many less temporary objects are allocated during an
+entire run of the weaver
+
+. First, the number of kilobytes of memory allocated from the heap
+during a weave of tools.jar with a code style trace aspect
+. Second, another run of the same thing
+. Third, this time using the insane aspect
+
+image:heapContents_161.jpg[image]
+
+So in terms of memory required, weaving the insane aspect into tools.jar
+created 1.4G of 'stuff' over the entire weaving process, compared to
+1.75G with 1.6.0.
+
+==== Loadtime weaving stress
+
+As well as addressing the memory usage of a single load time weaver, we
+have also looked at the use of load time weaving in a larger scale
+scenario, where multiple classloaders are being instantiated and
+discarded over time and each has an associated load time weaver. Under
+https://bugs.eclipse.org/bugs/show_bug.cgi?id=210470[bug 210470] we
+looked in detail at whether the lifecycle of the weaver instance
+correctly matched the lifecycle of the associated classloader. It did
+not, but now it does! Here is a memory usage graph for AspectJ1.6.1 -
+this shows an application that spawns 7 threads which run continuously
+for a few minutes. Each thread repeatedly creates a classloader, weaves
+500 classes using it then discards the classloader. You can see that
+over time the memory is recovered correctly and when all threads
+complete (and all classloaders are orphaned), all the weavers are
+discarded.
+
+First, AspectJ 1.6.0, in which memory was never correctly recovered and
+so an OutOfMemory problem would always occur eventually.
+
+image:memLtwStress_160.jpg[image]
+
+And now AspectJ 1.6.1:
+
+image:memLtwStress_161.jpg[image]
+
+=== Incremental compilation
+
+Following on from the work done to improve compilation under Eclipse in
+AspectJ 1.6.0 (https://bugs.eclipse.org/bugs/show_bug.cgi?id=221427[Bug
+221427] ) - we now support the building of 'broken code'
+(https://bugs.eclipse.org/bugs/show_bug.cgi?id=102733[bug 102733]). This
+is something the JDT has always been doing - where code containing
+errors continues to build (if recovery is possible) but should the
+actual methods containing the errors get invoked, an exception will be
+thrown at runtime. A number of users typically extract large projects
+from their library systems, knowing that they will only partially build
+in their current eclipse setup, but as long at they do not invoke the
+code containing the errors then they expect the rest of the project to
+run normally. AspectJ now allows this mode of operation, and it has the
+additional effect that the state of the project stays consistent, albeit
+with known errors, and this means AspectJ will more frequently do
+incremental builds rather than falling back to full builds because there
+was a compilation error.
+
+=== Language changes
+
+==== Optmized syntax for annotation value binding (https://bugs.eclipse.org/bugs/show_bug.cgi?id=234943[Bug234943])
+
+If only binding an annotation at a method-execution join point in order
+to access an *enum value* within it, there is a more optimal syntax that
+can be used to produce faster code. Given this setup:
+
+[source, java]
+....
+enum Colour { RED,GREEN,BLUE;}
+
+@interface ColouredAnnotation { Colour value(); }
+
+@ColouredAnnotation(Colour.RED)
+public void colouredMethod() { }
+....
+
+Current syntax:
+
+[source, java]
+....
+before(ColouredAnnotation anno): execution(* *(..)) && @annotation(anno) {
+  printTheColour(anno.value());
+}
+....
+
+New optional syntax:
+
+[source, java]
+....
+before(Colour col): execution(* *(..)) && @annotation(ColouredAnnotation(col)) {
+  printTheColour(col);
+}
+....