JVM/TI code review request (XS and M) (7182152)
Karen Kinnear
karen.kinnear at oracle.com
Mon Feb 4 07:19:53 PST 2013
Dan,
All 3 versions of the code looks good. Thank you for enabling the printing for product since
this type of problem is so hard to duplicate.
A small note, I think it would have been easier for the internal code logic
for the CPCE::check_no_old_or_obsolete_entries to reverse the true/false,
but no need to change. I would appreciate the comment from
is_interesting_method_entry copied to check_no_old_or_obsolete_entries
about virtual and final that f2 contains a method ptr instead of a vtable index.
In the jdk8 version in cpCache.cpp you've added the is_valid checks for metadata.
For a future cleanup, do we need f2_as_vfinal_method and is_interesting_method_entry
to do that as well?
Is redefineclasses supported in the MinimalVM?
thanks,
Karen
On Feb 1, 2013, at 2:55 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/
>
> 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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