Serguei, Looks good for me!
-Dmitry On 2014-10-30 04:05, serguei.spit...@oracle.com wrote: > The updated webrev: > http://cr.openjdk.java.net/~sspitsyn/webrevs/2014/jdk/6988950-JDWP-wrong-phase.2/ > > > The changes are: > - added a comment recommended by Staffan > - removed the ignore_wrong_phase() call from function classSignature() > > The classSignature() function is called in 16 places. > Most of them do not tolerate the NULL in place of returned signature and > will crash. > I'm not comfortable to fix all the occurrences now and suggest to return > to this > issue after gaining experience with more failure cases that are still > expected. > The failure with the classSignature() involved was observed only once in > the nightly > and should be extremely rare reproducible. > I'll file a placeholder bug if necessary. > > Thanks, > Serguei > > On 10/28/14 6:11 PM, serguei.spit...@oracle.com wrote: >> Please, review the fix for: >> https://bugs.openjdk.java.net/browse/JDK-6988950 >> >> >> Open webrev: >> http://cr.openjdk.java.net/~sspitsyn/webrevs/2014/jdk/6988950-JDWP-wrong-phase.1/ >> >> >> >> Summary: >> >> The failing scenario: >> The debugger and the debuggee are well aware a VM shutdown has >> been started in the target process. >> The debugger at this point is not expected to send any commands >> to the JDWP agent. >> However, the JDI layer (debugger side) and the jdwp agent >> (debuggee side) >> are not in sync with the consumer layers. >> >> One reason is because the test debugger does not invoke the JDI >> method VirtualMachine.dispose(). >> Another reason is that the Debugger and the debuggee processes >> are uneasy to sync in general. >> >> As a result the following steps are possible: >> - The test debugger sends a 'quit' command to the test debuggee >> - The debuggee is normally exiting >> - The jdwp backend reports (over the jdwp protocol) an >> anonymous class unload event >> - The JDI InternalEventHandler thread handles the >> ClassUnloadEvent event >> - The InternalEventHandler wants to uncache the matching >> reference type. >> If there is more than one class with the same host class >> signature, it can't distinguish them, >> and so, deletes all references and re-retrieves them again >> (see tracing below): >> MY_TRACE: JDI: >> VirtualMachineImpl.retrieveClassesBySignature: >> sig=Ljava/lang/invoke/LambdaForm$DMH; >> - The jdwp backend debugLoop_run() gets the command from JDI >> and calls the functions >> classesForSignature() and classStatus() recursively. >> - The classStatus() makes a call to the JVMTI GetClassStatus() >> and gets the JVMTI_ERROR_WRONG_PHASE >> - As a result the jdwp backend reports the JVMTI error to the >> JDI, and so, the test fails >> >> For details, see the analysis in bug report closed as a dup of >> the bug 6988950: >> https://bugs.openjdk.java.net/browse/JDK-8024865 >> >> Some similar cases can be found in the two bug reports (6988950 >> and 8024865) describing this issue. >> >> The fix is to skip reporting the JVMTI_ERROR_WRONG_PHASE error as >> it is normal at the VM shutdown. >> The original jdwp backend implementation had a similar approach >> for the raw monitor functions. >> Threy use the ignore_vm_death() to workaround the >> JVMTI_ERROR_WRONG_PHASE errors. >> For reference, please, see the file: src/share/back/util.c >> >> >> Testing: >> Run nsk.jdi.testlist, nsk.jdwp.testlist and JTREG com/sun/jdi tests >> >> >> Thanks, >> Serguei >> > -- Dmitry Samersoff Oracle Java development team, Saint Petersburg, Russia * I would love to change the world, but they won't give me the sources.
