[9] RFR(S): 8029443: 'assert(klass->is_loader_alive(_is_alive)) failed: must be alive' during VM_CollectForMetadataAllocation

[Tobias Hartmann]

Hi Coleen,

thanks for the review.
> *+           if (csc->is_call_to_interpreted() && stub_contains_dead_metadata(is_alive, csc->destination())) {*
> *+             csc->set_to_clean();*
> *+           }*
>
> This appears in each case.  Can you fold it and the new function into 
> a function like clean_call_to_interpreted_stub(is_alive, csc)?

I folded it into the function clean_call_to_interpreter_stub(..).

New webrev: http://cr.openjdk.java.net/~thartmann/8029443/webrev.01/

Thanks,
Tobias

>
> Thanks,
> Coleen
>
>>
>> So before the permgen removal embedded method* were oops and they 
>> were processed in relocInfo::oop_type loop.
>>
>> May be instead of specializing opt_virtual_call_type and 
>> static_call_type call site you can simple add a loop for 
>> relocInfo::metadata_type (similar to oop_type loop)?
>>
>> Thanks,
>> Vladimir
>>
>> On 7/14/14 4:56 AM, Tobias Hartmann wrote:
>>> Hi,
>>>
>>> please review the following patch for JDK-8029443.
>>>
>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8029443
>>> Webrev: http://cr.openjdk.java.net/~thartmann/8029443/webrev.00/
>>>
>>> *Problem*
>>> After the tracing/marking phase of GC, nmethod::do_unloading(..) checks
>>> if a nmethod can be unloaded because it contains dead oops. If class
>>> unloading occurred we additionally clear all ICs where the cached
>>> metadata refers to an unloaded klass or method. If the nmethod is not
>>> unloaded, nmethod::verify_metadata_loaders(..) finally checks if all
>>> metadata is alive. The assert in CheckClass::check_class fails because
>>> the nmethod contains Method* metadata corresponding to a dead Klass.
>>> The Method* belongs to a to-interpreter stub [1] of an optimized
>>> compiled IC. Normally we clear those stubs prior to verification to
>>> avoid dangling references to Method* [2], but only if the stub is 
>>> not in
>>> use, i.e. if the IC is not in to-interpreted mode. In this case the
>>> to-interpreter stub may be executed and hand a stale Method* to the
>>> interpreter.
>>>
>>> *Solution
>>> *The implementation of nmethod::do_unloading(..) is changed to clean
>>> compiled ICs and compiled static calls if they call into a
>>> to-interpreter stub that references dead Method* metadata.
>>>
>>> The patch was affected by the G1 class unloading changes (JDK-8048248)
>>> because the method nmethod::do_unloading_parallel(..) was added. I
>>> adapted the implementation as well.
>>> *
>>> Testing
>>> *Failing test (runThese)
>>> JPRT
>>>
>>> Thanks,
>>> Tobias
>>>
>>> [1] see CompiledStaticCall::emit_to_interp_stub(..)
>>> [2] see nmethod::verify_metadata_loaders(..),
>>> static_stub_reloc()->clear_inline_cache() clears the stub
>