icedtea-1.14 JamVM + OpenJDK 7 -version patch

[Xerxes Rånby]

fre 2011-05-27 klockan 12:48 +0200 skrev Xerxes Rånby:
> > What I currently observe are a
> > unsatisfied link error.
> > 
> > xranby at xranby-ESPRIMO-P7935:~/test
> > $ ../icedtea-1.14/openjdk.build/j2sdk-image/bin/java Linpack 
> > java.lang.UnsatisfiedLinkError: registerNatives
> > 	at sun.misc.Perf.registerNatives(Native Method)
> > 	at sun.misc.Perf.<clinit>(Perf.java:536)
> ...
> > 	at sun.misc.PerfCounter.<clinit>(PerfCounter.java:51)
> > 	at java.net.URLClassLoader.defineClass(URLClassLoader.java:448)
> > 
> > The URLClassLoader uses sun.misc.Perf to register startup time.
> > 
> > I start to think this are a bug in OpenJDK 7 that the sun.misc.Perf
> > constructor expects to be able to use the native registerNatives method
> > in libhprof.so without explicilty making sure that this library have
> > already been loaded.
> > 
> > The libhprof.so are part of the Hotspot JVMTI implementation so it are
> > no surprise that JamVM currently dont not load it.

The attached patch fix this UnsatisfiedLinkError by simply removing the
use of sun.misc from the OpenJDK 7 ClassLoader and URLClassLoader. This
makes it possible to use the OpenJDK 7 classes in combination with other
JVM's than Hotspot.

I think this are a valid fix since the hooks added using sun.misc.Perf
to monitor ClassLoader bootup time are not part of the public
ClassLoader API. These hooks do not exist in OpenJDK 6 and I can not
find any refernce to validate their existance in OpenJDK 7. I think they
are leftovers from some old ClassLoader speed regression investigation
and should be considered as debug code.

If someone like this debug code and have a suggestion how to properly
re-engineer sun.misc to support other JVM's than Hotspot im all ear.

> 
> 
> For clarification,the native method in libhprof.so void
> registerNative(void) called by the sun.misc.Perf constructor are not the
> same "RegisterNatives" as the JNI interface RegisterNatives
> http://download.oracle.com/javase/6/docs/technotes/guides/jni/spec/functions.html#wp17734
> 
> 
> Xerxes

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