RFR 8163127: Debugger classExclusionFilter does not work correctly with method references
Daniil Titov
daniil.x.titov at oracle.com
Tue Jan 29 19:40:47 UTC 2019
Hi JC,
Could you please say are you OK with this new version of the fix?
Thanks!
--Daniil
On 1/26/19, 11:35 AM, "Chris Plummer" <chris.plummer at oracle.com> wrote:
Looks good.
thanks,
Chris
On 1/26/19 11:23 AM, Daniil Titov wrote:
> Hi Chris,
>
> Please review a new version of the patch that moves the disabling of the single stepping into ConstantPool::klass_at_impl().
>
> Mach5 jdk_jdi, vmTestbase_nsk_jdi, vmTestbase_nsk_jdb and serviceability tests, as well as all tier1,tier2 and tier3 tests successfully passed.
>
> Webrev: http://cr.openjdk.java.net/~dtitov/8163127/webrev.03/
> Bug: https://bugs.openjdk.java.net/browse/JDK-8163127
>
> Thanks!
> --Daniil
>
> On 1/24/19, 11:19 AM, "Chris Plummer" <chris.plummer at oracle.com> wrote:
>
> Hi Daniil,
>
> Thanks for the stack track. I was just about to send an email asking for
> it when your new RFR arrived.
>
> The fix looks good. I think you also need to apply it here:
>
> InterpreterRuntime::ldc()
> InterpreterRuntime::anewarray()
> InterpreterRuntime::multianewarray()
> InterpreterRuntime::quicken_io_cc()
>
> I wonder if it wouldn't be better if you moved the disabling into
> ConstantPool::klass_at_impl()
>
> thanks,
>
> Chris
>
> On 1/24/19 10:38 AM, Daniil Titov wrote:
> > Hi Chris and JC,
> >
> > Thank you for reviewing this change. Please review a new version of the fix that uses
> > the approach Chris suggested ( disabling the single stepping during the class resolution).
> >
> > Just in case please find below the stack trace for this case when loadClass() method is entered.
> >
> > #0 SystemDictionary::load_instance_class(Symbol*, Handle, Thread*) at open/src/hotspot/share/classfile/systemDictionary.cpp:1502
> > #1 SystemDictionary::resolve_instance_class_or_null(Symbol*, Handle, Handle, Thread*) at open/src/hotspot/share/classfile/systemDictionary.cpp:853
> > #2 SystemDictionary::resolve_instance_class_or_null_helper(Symbol*, Handle, Handle, Thread*) at open/src/hotspot/share/classfile/systemDictionary.cpp:271
> > #3 SystemDictionary::resolve_or_null(Symbol*, Handle, Handle, Thread*) at open/src/hotspot/share/classfile/systemDictionary.cpp:254
> > #4 SystemDictionary::resolve_or_fail(Symbol*, Handle, Handle, bool, Thread*) at open/src/hotspot/share/classfile/systemDictionary.cpp:202
> > #5 ConstantPool::klass_at_impl(constantPoolHandle const&, int, bool, Thread*) at open/src/hotspot/share/oops/constantPool.cpp:483
> > #6 ConstantPool::klass_at(int, Thread*) at open/src/hotspot/share/oops/constantPool.hpp:382
> > #7 InterpreterRuntime::_new(JavaThread*, ConstantPool*, int) at open/src/hotspot/share/interpreter/interpreterRuntime.cpp:234
> > # 8 <Stub Code>
> > ....
> >
> > Webrev: http://cr.openjdk.java.net/~dtitov/8163127/webrev.02/
> > Bug: https://bugs.openjdk.java.net/browse/JDK-8163127
> >
> > Thanks,
> > Daniil
> >
> > On 1/23/19, 3:53 PM, "Chris Plummer" <chris.plummer at oracle.com> wrote:
> >
> > Hi Daniil,
> >
> > I don't see an explanation for why fromDepth is 1 and afterPopDepth is 4.
> >
> > currentDepth = getThreadFrameCount(thread);
> > fromDepth = step->fromStackDepth;
> > afterPopDepth = currentDepth-1;
> >
> > step->fromStackDepth got setup when single stepping was first setup for
> > this thread. There was also a notifyFramePop() done at this time, but I
> > think that's just to catch exiting from the method you were single
> > stepping in, and has no bearing in the case we are looking at here,
> > where we area still some # of frames below where we user last issued a
> > STEP_INTO. The FRAME_POP we are receiving now is not the one for when
> > step->fromStackDepth was setup, but is for when we stepped into a
> > filtered method. I think this is what the "fromDepth > afterPopDepth"
> > check is for. I think the current logic is correct for intended handling
> > of a FRAME_POP event. Although your fix is probably solving the problem,
> > I get the feeling it is enabling single stepping too soon in many cases.
> > That many not turn up as an error in any tests, but could cause
> > debugging performance issues, or for the user to see spurious single
> > step events that they were not expecting.
> >
> > I think the bug actually occurs long before we ever get to this point in
> > the code (and we should in fact not be getting here). In my last entry
> > in the bug I mentioned JvmtiHideSingleStepping(), and how it is used to
> > turn off single stepping while we are doing invoke and field resolution,
> > but doesn't seem to be used during class resolution, which is what we
> > are doing here. If it where used, then the agent would never even see
> > the SINGLE_STEP when loadClass() is entered, therefore no
> > notifyFramePop() would be done, and we would not be relying on this code
> > in handleFramePopEvent(). Instead, we would receive the next SINGLE_STEP
> > event after cp resolution is complete, and we are finally executing the
> > now resolved opc_new opcode.
> >
> > I'm hoping Serguei and/or Alex can also comment on this, since I think
> > they were dealing with JvmtiHideSingleStepping() last month.
> >
> > thanks,
> >
> > Chris
> >
> >
> >
> > On 1/17/19 6:08 PM, Daniil Titov wrote:
> > > Please review the change that fixes JDB stepping issue for a specific case when the single step request was initiated earlier in the stack, previous calls were for methods in the filtered classes (single stepping was disabled), handleMethodEnterEvent() re-enabled stepping and the first bytecode upon entering the current method requires resolving constant pool entry. In this case the execution resumes in java.lang.Classloader.loadClass() and since it is also a filtered class the single stepping is getting disabled again (stepControl.c :593). When loadClass() exits a notifyFramePop() is called on the loadClass() frame but due to condition fromDepth >= afterPopDepth at stepControl.c :346 (that doesn't hold in this case, in this case fromDepth is 1 and afterPopDepth is 4) the notifyFramePop() fails to enable single stepping back. The fix removes the excessive condition fromDepth >= afterPopDepth in notifyFramePop() method (stepControl.c:346) to ensure that when a method cal!
> > > led from the stepping frame (and during which we had stepping disabled) has returned the stepping is re-enabled to continue instructions steps in the original stepping frame.
> > >
> > > Webrev: http://cr.openjdk.java.net/~dtitov/8163127/webrev.01
> > > Bug: https://bugs.openjdk.java.net/browse/JDK-8163127
> > >
> > > Thanks!
> > > --Daniil
> > >
> > >
> >
> >
> >
> >
> >
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