tracing jni Get<Primitive>TypeFields calls
mjw at redhat.com
Wed Mar 17 05:21:22 PDT 2010
Hi hotspot runtime devs,
Jon VanAlten wrote an extensive testsuite for using the static dtrace
markers with systemtap (see the icedtea distro-pkg-dev mailinglist) and
we found out that the JNI Get<PrimitiveType>Field probes only trigger
when disabling the UseFastJNIAccessors. This makes sense when looking
through the code. So we added documentation to the systemtap
hotspot_jni.stp tapset to document this fact.
- Should this be documented anywhere else?
- Would it make sense to enable -XX:-UseFastJNIAccessors when
-XX:+ExtendedDTraceProbes is given?
- quicken_jni_functions() is only called once and so only checks
preconditions for enabling them once at startup. I couldn't
immediately see how one would deoptimize these when an
enable/disable flag was dynamically toggled.
Is there, or should there be such a mechanism?
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