Graal: [svm] add support for sun.misc.Perf

[martinlippert]

I am trying to use the Attach tools within a native image, but down the road the implementation causes an exception because of missing support in sun.misc.Perf:

java.lang.UnsatisfiedLinkError: sun.misc.Perf.attach(Ljava/lang/String;II)Ljava/nio/ByteBuffer; [symbol: Java_sun_misc_Perf_attach or Java_sun_misc_Perf_attach__Ljava_lang_String_2II]
    at com.oracle.svm.jni.access.JNINativeLinkage.getOrFindEntryPoint(JNINativeLinkage.java:145)
    at com.oracle.svm.jni.JNIGeneratedMethodSupport.nativeCallAddress(JNIGeneratedMethodSupport.java:57)
    at sun.misc.Perf.attach(Perf.java)
    at sun.misc.Perf.attachImpl(Perf.java:270)
    at sun.misc.Perf.attach(Perf.java:200)
    at sun.jvmstat.perfdata.monitor.protocol.local.PerfDataBuffer.<init>(PerfDataBuffer.java:64)
    at sun.jvmstat.perfdata.monitor.protocol.local.LocalMonitoredVm.<init>(LocalMonitoredVm.java:68)
    at 
sun.jvmstat.perfdata.monitor.protocol.local.MonitoredHostProvider.getMonitoredVm(MonitoredHostProvider.java:27)
    at sun.tools.attach.HotSpotAttachProvider.listVirtualMachines(HotSpotAttachProvider.java:101)
    at com.sun.tools.attach.VirtualMachine.list(VirtualMachine.java:147)
    at org.test.tools.VirtualMachineTest.main(VirtualMachineTest.java:17)

It would be awesome if support for this could be added to SVM.

[peter-hofer]

Are you planning on attaching to a full JVM (HotSpot)? Supporting sun.misc.Perf might not be sufficient for that on its own. If you're trying to attach to a native image, I doubt that we currently support the required interfaces.

[martinlippert]

@peter-hofer I am trying to attach to a regular HotSpot JVM. I don't know whether support for sun.misc.Perf is enough to support that case, this is just how far I got up to now in my experiments.

And yes, I am aware that native images don't support any of these mechanisms yet, but since I don't want to attach to a native image, that is fine for me... :-)

[peter-hofer]

It looks like sun.misc.Perf is implemented in HotSpot itself and uses shared memory with knowledge about internal data structures. I don't think this is very high-priority at the moment.

[peter-hofer]

@thurka informed me that we do have some code for that in GraalVM Enterprise Edition and support for sun.misc.Perf will eventually be added.

[sogaiu]

On the note of trying to use the Attach API, there is this multi-platform C-based project jattach. May be it can be used / adapted for use via JNI / JNA / etc. to work with native-image?

[peter-hofer]

With the native-image C interface, that is a certainly possible!