Code review request: CR 7141259 Native stack is missing in hs_err

[Zhengyu Gu]

The cause of the problem is that decode acquires lock inside signal 
handler and generates assertion.

The decoder is only used by error handler at this point, so it is safe 
to run without lock. Locking has many undesirable consequences under 
this scenario, besides signal handler issue, the error handler can be 
invoked when the thread is holding other locks, as David Holmes suggested.

But it will also be used in upcoming native memory tracking code, which 
potentially can have multi-thread invoking decoder, so synchronization 
is needed.

The proposed fix is to let error handler set decoder to single threaded 
mode, in which mode no lock is acquired.


Please review
Webrev: http://cr.openjdk.java.net/~zgu/7141259/webrev.00/


Thanks,

-Zhengyu