RFR: 8311993: Test serviceability/sa/UniqueVtableTest.java failed: duplicate vtables detected

[Chris Plummer]

On Thu, 22 Aug 2024 19:50:01 GMT, Alex Menkov <amenkov at openjdk.org> wrote:

> On Windows SA agent gets a class vtable from symbols, exported from jvm.dll (it exports symbols like "??_7" + type + "@@6B@").
> But symbol lookup function first requests WinDbg about the symbol.
> Sometimes WinDbg routine IDebugSymbols::GetOffsetByName() returns offset for both class and class pointer types. Returned offsets correspond to symbols like "jvm!class_name::`vftable'".
> The behavior is intermittent, I was not able to find what is the reason.
> The fix adds workaround for the case - if GetOffsetByName succeeded, we check if corresponding symbol contains requested one.
> So it returns expected offset for non-vtable symbols like "MaxJNILocalCapacity" (GetOffsetByName returns offset for "jvm!MaxJNILocalCapacity"), but returns 0 for vtlb lookup.
> 
> Additionally added check for results of IDebugSymbols::SetImagePath/SetSymbolPath
> 
> Testing: tier1,tier2,hs-tier5-svc

Why do we rely on GetOffsetByName() when we can already lookup directly from the dll, and this is in fact the fallback already in place when GetOffsetByName() fails?

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PR Comment: https://git.openjdk.org/jdk/pull/20684#issuecomment-2310645991