JVM/TI code review request (XS and M) (7182152)

Coleen Phillimore coleen.phillimore at oracle.com
Mon Feb 4 06:26:33 PST 2013

On 2/1/2013 6:55 PM, Daniel D. Daugherty wrote:
> And here is the webrev for the new tests (relative to JDK8-T&L):
> http://cr.openjdk.java.net/~dcubed/8007420-webrev/0-jdk8-tl/
> As always, comments and suggestions are welcome.
> Dan
> On 2/1/13 4:39 PM, Daniel D. Daugherty wrote:
>> > There are two new tests that will be pushed to the JDK repos using
>> > a different bug ID (not yet filed):
>> New bug is now filed:
>>     8007420 add test for 6805864 to com/sun/jdi, add test for 7182152
>>             to java/lang/instrument
>>     http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8007420
>>     https://jbs.oracle.com/bugs/browse/JDK-8007420
>> Of course, the tests cannot be pushed until the HSX changes have made
>> it into a promoted build and thus available to JDK8-T&L.
>> Dan
>> On 2/1/13 12:55 PM, Daniel D. Daugherty wrote:
>>> Greetings,
>>> I have a fix for the following JVM/TI bug:
>>>     7182152 Instrumentation hot swap test incorrect monitor count
>>>     http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7182152
>>>     https://jbs.oracle.com/bugs/browse/JDK-7182152
>>> The fix for the bug in the product code is one line:
>>> src/share/vm/oops/klassVtable.cpp:
>>> @@ -992,18 +1020,50 @@
>>>            // RC_TRACE macro has an embedded ResourceMark
>>>            RC_TRACE(0x00200000, ("itable method update: %s(%s)",
>>>              new_method->name()->as_C_string(),
>>>              new_method->signature()->as_C_string()));
>>>          }
>>> -        break;
>>> +        // cannot 'break' here; see for-loop comment above.
>>>        }
>>>        ime++;
>>>      }
>>>    }
>>>  }
>>> and is applicable to JDK7u10/HSX-23.6 and JDK7u14/HSX-24. Coleen
>>> already fixed the bug as part of the Perm Gen Removal (PGR) project
>>> in HSX-25. Yes, we found a 1-line bug fix buried in the monster PGR
>>> changeset. Many thanks to Coleen for her help in this bug hunt!
>>> The rest of the code in the webrevs are:
>>> - additional JVM/TI tracing code backported from Coleen's PGR changeset
>>> - additional JVM/TI tracing code added by me and forward ported to 
>>> HSX-25
>>> - a new -XX:TraceRedefineClasses=16384 flag value for finding these
>>>   elusive old or obsolete methods
>>> - exposure of some printing code to the PRODUCT build so that the new
>>>   tracing is available in a PRODUCT build
>>> You might be wondering why the new tracing code is exposed in a PRODUCT
>>> build. Well, it appears that more and more PRODUCT bits deployments are
>>> using JVM/TI RedefineClasses() and/or RetransformClasses() at run-time
>>> to instrument their systems. This bug (7182152) was only intermittently
>>> reproducible in the WLS environment in which it occurred so I made the
>>> tracing available in a PRODUCT build to assist in the hunt.
>>> Raj from the WLS team has also verified that the HSX-23.6 version of
>>> fix resolves the issue in his environment. Thanks Raj!
>>> Here are the URLs for the three webrevs:
>>> http://cr.openjdk.java.net/~dcubed/7182152-webrev/0-hsx23.6/
>>> http://cr.openjdk.java.net/~dcubed/7182152-webrev/0-hsx24/
>>> http://cr.openjdk.java.net/~dcubed/7182152-webrev/0-hsx25/

In cpCache.cpp:

RC_TRACE_NO_CR(0x00004000, (""));

Can this "searchable prefix" be defined in jvmtiTracing with the rest of 
the RC_TRACE macros as some descriptive RC_TRACE name? Doesn't have to 
be long but this is distracting stuff.   Also, if you change this 
searchable prefix, you'd only have to change it once.

In jvmtiRedefineClasses.cpp why can't dump_methods just print the 
methods without these RC_TRACE macros?   And some is printed and some is 
not?  This is really hard to read.   The indentation came out strange in 
the webrev too.
It looks like the call to dump_methods() is covered by one of these 
RC_TRACE macros.  Why isn't that enough?   This is really distracting 
because I keep wondering why it's RC_TRACE_NO_CR (don't file a CR??) 
rather than reading the code.   Oh, it's no carriage return.   Ugh.   I 
still would like dump_methods to always dump all the methods so if 
you're debugging this you can temporarily paste this call various places 
without trying to figure out which RC_TRACE number to give it.


>>> I have run the following test suites from the JPDA stack on the
>>> JDK7u10/HSX-23.6 version of the fix with -XX:TraceRedefineClasses=16384
>>> specified:
>>>     sdk-jdi
>>>     sdk-jdi_closed
>>>     sdk-jli
>>>     vm-heapdump
>>>     vm-hprof
>>>     vm-jdb
>>>     vm-jdi
>>>     vm-jdwp
>>>     vm-jvmti
>>>     vm-sajdi
>>> The tested configs are:
>>>     {Solaris-X86, WinXP}
>>>       X {Client VM, Server VM}
>>>       X {-Xmixed, -Xcomp}
>>>       X {product, fastdebug}
>>> With the 1-liner fix in place, the new tracing code does not find any
>>> instances of this failure mode in any of the above test suites. Without
>>> the the 1-liner fix in place, the new tracing code finds one instance
>>> of this failure mode in the above test suites:
>>>     test/java/lang/instrument/IsModifiableClassAgent.java
>>> There are two new tests that will be pushed to the JDK repos using
>>> a different bug ID (not yet filed):
>>>     test/com/sun/jdi/RedefineAbstractClass.sh
>>> test/java/lang/instrument/RedefineSubclassWithTwoInterfaces.sh
>>> There will be a separate review request for the new tests.
>>> I'm currently running the JPDA stack of tests on the JDK7u14/HSX-24
>>> and JDK8-B75/HSX-25 versions of the fix. That testing will likely
>>> take all weekend to complete.
>>> Thanks, in advance, for any comments and/or suggestions.
>>> Dan

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