On 11/07/2012 06:59 PM, Martin Buchholz wrote:
We've also seen deadlocks in accessing annotations in the wild.
So, many thanks for working on this (both performance improvements and
deadlock removal).
We don't have a test case to contribute, but here's a stacktrace:
That's one thread. What about the other(s)?
I guess this is similar to http://bugs.sun.com/view_bug.do?bug_id=7122142
Various locks are involved:
- AnnotationType.getInstance is a static synchronized method (locks on
AnnotationType.class)
- Class.initAnnotationsIfNecessary is an instance synchronized method
(locks on various .class instances)
lazy initialization sequence can take various ordering combinations
among threads (recursing on loading annotations on annotations - the
meta annotations - when requested by the AnnotationType init).
The proposed patch removes blocking synchronization on
Class.initAnnotationsIfNecessary (replacing this method with another one
that has no blocking synchronization). Therefore just one lock remains
in such scenarios (AnnotationType.getInstance) and there's no dead-lock
with just one lock ;-)
Regards, Peter
sun.reflect.annotation.AnnotationType.getInstance(AnnotationType.java:80)
sun.reflect.annotation.AnnotationParser.parseAnnotation(AnnotationParser.java:220)
sun.reflect.annotation.AnnotationParser.parseAnnotations2(AnnotationParser.java:87)
sun.reflect.annotation.AnnotationParser.parseAnnotations(AnnotationParser.java:70)
java.lang.Class.initAnnotationsIfNecessary(Class.java:3093)
java.lang.Class.getAnnotation(Class.java:3050)
sun.reflect.annotation.AnnotationType.<init>(AnnotationType.java:130)
sun.reflect.annotation.AnnotationType.getInstance(AnnotationType.java:83)
sun.reflect.annotation.AnnotationParser.parseAnnotation(AnnotationParser.java:220)
sun.reflect.annotation.AnnotationParser.parseAnnotations2(AnnotationParser.java:87)
sun.reflect.annotation.AnnotationParser.parseAnnotations(AnnotationParser.java:70)
java.lang.Class.initAnnotationsIfNecessary(Class.java:3093)
java.lang.Class.getAnnotation(Class.java:3050)
sun.reflect.annotation.AnnotationType.<init>(AnnotationType.java:130)
sun.reflect.annotation.AnnotationType.getInstance(AnnotationType.java:83)
sun.reflect.annotation.AnnotationParser.parseAnnotation(AnnotationParser.java:220)
sun.reflect.annotation.AnnotationParser.parseAnnotations2(AnnotationParser.java:87)
sun.reflect.annotation.AnnotationParser.parseAnnotations(AnnotationParser.java:70)
java.lang.Class.initAnnotationsIfNecessary(Class.java:3093)
java.lang.Class.getAnnotation(Class.java:3050)
Martin
On Wed, Nov 7, 2012 at 9:11 AM, Peter Levart <peter.lev...@gmail.com
<mailto:peter.lev...@gmail.com>> wrote:
On 11/06/2012 08:37 AM, Peter Levart wrote:
Hi all,
I have prepared a better patch. It addresses the goals of
JEP-149 more seriously. I also have some benchmarks. Stay tuned...
Regards, Peter
For easier viewing, here's also a webrev:
http://dl.dropbox.com/u/101777488/jdk8-hacks/JEP-149/webrev/index.html
Regards, Peter
