Code review request: CR 7141259 Native stack is missing in hs_err
zhengyu.gu at oracle.com
Mon Feb 6 06:30:53 PST 2012
I total agree that it is a bit of hack. The problem is that, decoder
actually hides behind os::dll_address_to_function_name(), which makes it
less flexible in design. Unless we are willing to mark it as
multi-thread unsafe, and manage decoder instance and lock outside the
scope. Native memory tracking has such flexibility, I think that the
real issue is how to redesign dll_address_to_function_name() API.
On 2/6/2012 3:14 AM, David Holmes wrote:
> Hi Zhengyu,
> On 4/02/2012 8:12 AM, Zhengyu Gu wrote:
>> Thanks for reviewing. I think I made wrong assumption that the thread is
>> the last running thread.
>> 803 // This should be the only running thread, decoder can safely run in
>> 804 // single threaded mode without acquiring lock
>> 805 Decoder::set_single_threaded(true);
>> To avoid locking in error handler, the only solution I can think of, is
>> to have its own private decoder.
>> Please see revised webrev:
> This seems functionally ok. It is a bit strange to have a static API
> built on the assumption of a singleton instance now having to special
> case "is this the VM error thread" and use more than once instance,
> but I think changing that requires revisiting the whole Decoder
>>> Later when there are multiple users of the Decoder I don't know how
>>> you will fix this because those other users can run concurrently with
>>> report_and_die(). That said I'm unclear what it is about the Decoder
>>> that requires locking - what state does it maintain? Is there a reason
>>> not to create a Decoder only when needed?
>> Decoder is created on demand, but would prefer to be shared, since it
>> can consume noticeable amount memory on Unix platform, by loading Elf
>> files' symbol tables and string tables into memory (not impact on
>> Windows). The lock is needed to protect a linked list structure in Elf
>> decoder, or current file position.
>>> In decoder.cpp you can still use MutexLockerEx and as it will take a
>>> null mutex and just act as a no-op eg:
>>> MutexLockerEx locker( _single_thread ? NULL : _decoder_lock, true);
>>>> Please review
>>>> Webrev: http://cr.openjdk.java.net/~zgu/7141259/webrev.00/
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