RFR (S) 8209889: RedefineStress tests crash

[dean.long at oracle.com]

So having a raw CompileTask* is like having a raw Method*.  I'm tempted 
to suggest a new CompiledTaskHandle, but it would only be used in one 
place, so how about changing CompileTaskWrapper so we could do something 
like this instead:

     CompileTaskWrapper ctw(queue->get());
     CompileTask* task = ctw.task();

CompileTaskWrapper would need to be able to handle a NULL task gracefully.

dl

On 10/4/18 4:45 AM, coleen.phillimore at oracle.com wrote:
> Summary: Create CompileTaskWrapper before potential safepoint
>
> open webrev at http://cr.openjdk.java.net/~coleenp/8209889.01/webrev
> bug link https://bugs.openjdk.java.net/browse/JDK-8209889
>
> MetadataOnStackMark needs to find the CompileTask in the current 
> thread, or else the Method isn't marked as being alive, so if it's 
> old/obsolete, it is freed.  There are checks to disable adding old 
> methods to the compile queue but if the method is redefined after this 
> point, there may be a preexisting bug that we compile an old method.  
> This change just fixes the crash.
>
> Can some compiler person (Martin?) look at where I moved 
> possibly_add_compiler_threads and let me know if that looks okay? 
> There's a comment in the change that says why you need to create the 
> CompileTaskWrapper before that call.  I couldn't find a place to put a 
> NoSafepointVerifier.
>
> Tested with the test that failed, which doesn't reproduce the bug 
> except rarely, and test/hotspot/jtreg/compiler tests.  tier1 an 2 in 
> progress.
>
> Thanks,
> Coleen