RFR (XS): 8234608: [TESTBUG] Memory leak in gc/g1/unloading/libdefine.cpp

[Thomas Schatzl]

Hi Ian/Man,

On 28.01.20 04:13, Man Cao wrote:
> Hi all,
> 
> Could anyone review this small patch contributed by my colleague Ian Rogers
> (irogers at google.com)?
> Bug: https://bugs.openjdk.java.net/browse/JDK-8234608
> Webrev: https://cr.openjdk.java.net/~manc/8234608/webrev.00/
> 
> -Man
> 

   the change looks good - but the test testing this is broken. In fact, 
the tests doing the redefinition via JVMTI do not even run at all. This 
may be why the error that has been "fixed" in this change about passing 
the byte stream to the RedefineClass method has never been noticed before.

I did some hacking to enable redefinition in the tests, and then 
immediately had to fix the JNI method name, which once more indicates 
that the appropriate tests were never run... :(

My changes are available at 
http://cr.openjdk.java.net/~tschatzl/8234608/webrev/ ; however the 
test(s) fail at the RedefineClasses call (with and without your patch) with

[...]vmTestbase/gc/g1/unloading/libdefine.cpp: Failed to call 
RedefineClasses():
	the function returned error 60
	For more info about this error see the JVMTI spec

which means

  JVMTI_ERROR_INVALID_CLASS_FORMAT (60)
     A new class file is malformed (the VM would return a 
ClassFormatError).

I have no further clue about what's wrong here. Maybe you are 
interested/have time to investigate more but I need to give up for today 
at least. Otherwise it's probably best to just add some links to the CR 
for somebody else to continue.

Thanks,
   Thomas