RFR: JDK-8174994: SA: clhsdb printmdo throws WrongTypeException when attached to a process with CDS
jini.george at oracle.com
Fri Apr 6 16:21:50 UTC 2018
Requesting reviews for: https://bugs.openjdk.java.net/browse/JDK-8174994
While trying to identify the type given an address, a WrongTypeException
was getting thrown with various clhsdb commands (like printmdo, jstack,
etc). This was since SA tries to map an address to a hotspot C++ type by
comparing the vtable address to the vtable address values of known
types. With CDS, since the vtables are copied over for the Metadata
classes, the vtable addresses themselves don't match (though, of course,
the contents will), and SA errors out.
The fix has been implemented by making changes to read in the md region
(consisting of the c++ vtables) of the CDS archive in SA, and mapping
the vtable addresses to the corresponding metadata type (ConstantPool,
InstanceKlass, InstanceClassLoaderKlass, InstanceMirrorKlass,
InstanceRefKlass, Method, ObjArrayKlass, TypeArrayKlass).
For corefiles, an additional modification has been done to have the
replicated FileMapHeader structure (from
src/hotspot/share/memory/filemap.hpp, which is replicated in SA in
ps_core.c), to be in sync with the corresponding definition in
Test cases to test both live and corefile debugging are being added with
this. These and other SA tests pass on Mach5.
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