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

Bernard Traversat bernard.traversat at oracle.com
Fri Feb 1 18:57:50 PST 2013

Excellent!

Cheers,

B.

On Feb 1, 2013, at 11:55 AM, Daniel D. Daugherty <daniel.daugherty at oracle.com> 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/viewbug.do?bugid=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 @@ // RCTRACE macro has an embedded ResourceMark RCTRACE(0x00200000, ("itable method update: %s(%s)", newmethod->name()->asCstring(), newmethod->signature()->asCstring())); } - 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-jdiclosed 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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