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

Daniel D. Daugherty daniel.daugherty at oracle.com
Mon Feb 4 09:19:55 PST 2013

Adding back dropped aliases and people...

Thanks for reviewing the first test! Replies embedded below.

On 2/4/13 8:09 AM, Coleen Phillimore wrote:
> 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/
> I am so impressed that you were able to write a test for this.

Thanks. The shame of it is that I wrote this test back when I fixed
the 1-liner bug back in 2009. The test never got pushed to the JDK
repo so the regression was able to sneak in later. Sigh.

> I can't follow this shell script at all.   Who calls createJavaFile?

This test is written using the JDI ShellScaffold.sh infrastructure
in test/com/sun/jdi/ShellScaffold.sh (1106 lines of pure joy!).
createJavaFile() is a hook called by ShellScaffold.sh to create
the .java file that will be exercised by the test.

> http://cr.openjdk.java.net/~dcubed/8007420-webrev/0-jdk8-tl/test/com/sun/jdi/RedefineAbstractClass.sh.html 
> I think a limited amount of duplication of Java code in the test 
> directory is worth having these scripts be more simple.   It looks 
> like the only thing that substituted in the java test is the main 
> class, but lines 66 to 104 can be a stand-alone java source file.

No, the main class just has the breakpoints.

This is the line for the redefinition:

   76     // @1 uncomment System.out.println("This is call " + counter + 
" to checkFunc");

so the original version doesn't have this line and new version
has this line. The glue that makes all that work is in TestScaffold.sh.

I don't remember for sure, but I think JDI ShellScaffold.sh does not
work well with multiple .java files. It has been a long time since
I've written a test in this format. These JDI .sh tests are meant to
be standalone if need be. That's why this comment is always here:

  143 # You could replace this next line with the contents
  144 # of ShellScaffold.sh and this script will run just the same.
  145 mysetup

> Again, I can't really follow the logic here and I dread ever having to 
> debug this.   Can you simplify this?

Which part? By definition, RedefineClasses tests are complicated because
you have to have at least two versions of .class files, sometimes more.
This test is reproducing a bug using "jdb" so there is all the infra
that supports controlling "jdb".

I think this test is as simple as it can be given the context, but I'm
open to specific simplification suggestions.

Did you plan to review the java.lang.instrument (JLI) test? It's a bit
more convoluted because it is trying to mimic the WLS test case.


> Thanks,
> Coleen
>> 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 
>>>> 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/
>>>> 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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