Safepoint Deadlock Diagnosis

[Peng Du]

Hello, list

I have been witnessing deadlocks of the HotSpot I am working on. I tried 
everything I know
to diagnose this. Here is what I found: the "main" JavaThread always 
ended up somewhere
in the stub SharedRuntime::handle_wrong_method(). HotSpot would then 
deadlock at this point.
In to the thread dump, I saw all threads are: _thread_blocked. The 
method that was patched
with this stub is "java_lang_math_log" (frame 12 @ 0x00007f832173b40e).

I have attached the backtrace and thread dump in the email. Can someone 
hint on what might
be the reason for this deadlock?

Thanks!


-Peng
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