RFR: 8168914: Crash in ClassLoaderData/JNIHandleBlock::oops_do during concurrent marking

[Kim Barrett]

> On Feb 23, 2017, at 1:09 PM, Erik Helin <erik.helin at oracle.com> wrote:
> 
> On 02/21/2017 04:49 PM, Erik Helin wrote:
>> On 02/21/2017 02:57 AM, Kim Barrett wrote:
>>>> On Feb 20, 2017, at 5:52 PM, David Holmes <david.holmes at oracle.com>
>>>> wrote:
>>>>> 02 -> 03:
>>>>> - Only use load_acquire when reading the size for the "head" chunk
>>>> 
>>>> Sorry but I don't like the way this is done - the conditional may end
>>>> up being more expensive than the unnecessary load-acquire. Unrolling
>>>> the first loop iteration, as per the email discussion, is a better
>>>> way to go IMO.
>>> 
>>> +1
>> 
>> David, Kim, please see new patches at:
>> - inc: http://cr.openjdk.java.net/~ehelin/8168914/03-04/
>> - full: http://cr.openjdk.java.net/~ehelin/8168914/04/
> 
> I got a few comments from StefanK offline so I figured that I might as
> well create new patch including other comments as well.
> 
> Please see new patches at:
> - inc: http://cr.openjdk.java.net/~ehelin/8168914/04-05/
> - full: http://cr.openjdk.java.net/~ehelin/8168914/05/
> 
> The changes made to version 04 includes:
> - Prefix all fields with underscore (StefanK)

hotspot seems relatively evenly split on underscore prefixes for public data members.
other codebases I’ve seen tend toward unqualified.
style guide does say underscore prefix without mentioning exceptions.

> - Rename all arguments of type oop* to `p` (StefanK)
> - Group fields together in Chunk (StefanK)
> - Make oops_do_chunk private (Kim, David, Thomas)
> - Remove casts to intptr_t (Kim, David, Thomas)
> 
> Thanks everyone for the thorough reviewing!
> Erik
> 
>> Thanks,
>> Erik

Still looks good.