RFR: 8278965: crash in SymbolTable::do_lookup

[Coleen Phillimore]

On Fri, 10 Feb 2023 02:30:34 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Please review this small change to hold the refcount of a super class name while calling handle_parallel_super_load. Contrary to what I wrote in JDK-8298061, the refcount in the Placeholder table should never go to one.  I can reproduce this with btree012 occasionally, so this fixes this too.
>> 
>> The include in placeholders.hpp is required to make the gtest compiled since placeholders header file has Symbol::maybe_increment_refcount and decrement calls.
>> 
>> Tested with the graal test that failed, and tier1-7.
>
> test/hotspot/gtest/classfile/test_placeholders.cpp line 39:
> 
>> 37:   JavaThread* T2 = THREAD;
>> 38:   // the thread should be in vm to use locks
>> 39:   ThreadInVMfromNative ThreadInVMfromNative(THREAD);
> 
> Nit: The variable name would normally be a shorter acronym `tivmfn`.

That's surprising that it compiled. I cut/pasted it from another test.

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PR: https://git.openjdk.org/jdk/pull/12491