Request for review (XS): 7197906: BlockOffsetArray::power_to_cards_back() needs to handle > 32 bit shifts

Srinivas Ramakrishna ysr1729 at gmail.com
Thu Sep 13 22:21:43 UTC 2012


Thanks Bengt; changes look good to me too, Hal, although i just looked at
the changes, and did not
check the code to see if there might be more instances of the fingered
anti-pattern. (I am pretty sure
you and John and other reviewers have covered that front well :-)

Bengt, any chance that the fix will get bkported also to 7uXX soon, for
some suitable value of XX?

thanks!
-- ramki

On Thu, Sep 13, 2012 at 8:27 PM, Bengt Rutisson
<bengt.rutisson at oracle.com>wrote:

>
> Hi Ramki,
>
> Thanks for looking at this!
>
> Here's a webrev based on the second patch that Hal sent out:
> http://cr.openjdk.java.net/~brutisso/7197906/webrev.02/
>
> Bengt
>
>
> On 2012-09-13 18:12, Srinivas Ramakrishna wrote:
>
> Hal, thanks for the catch and the fix!
>
> Bengt, might it be possible to host this as a traditional webrev in the
> usual place, to simplify review logistics?
>
> thanks!
> -- ramki
>
> On Thu, Sep 13, 2012 at 4:55 PM, Jianhao Mo <mojianhao at gmail.com> wrote:
>
>> Hi all,
>>
>>  Attached please find the new patch, modified according to John's advice.
>>
>>  Thanks Bengt again for the help :)
>>
>>  Regards,
>>
>>  Hal
>>
>> 2012/9/12 Jianhao Mo <mojianhao at gmail.com>
>>
>>> Hi all,
>>>
>>>  Could I get a couple of reviews for this small patch, please?
>>>
>>>  7197906: BlockOffsetArray::power_to_cards_back() needs to handle > 32
>>> bit shifts
>>>
>>>  CR link:
>>> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7197906
>>> Webrev:
>>> http://cr.openjdk.java.net/~brutisso/7197906/webrev.01/
>>> Contributed-by:
>>>  Hal Mo <kungu.mjh at taobao.com> from Alibaba Group(with OCA)
>>>
>>>  It may take a while before the CR link is publicly accessible.
>>>
>>>  In blockOffsetTable.hpp, there is an unexpected data truncation in
>>> power_to_cards_back(uint i), which may lead to crashing the VM on very
>>> large GC heaps.
>>> The problem could be reproduced easily on machines, that have enough
>>> memory, with:
>>>  $ java -Xmx135g -XX:+UseConcMarkSweepGC
>>>
>>>   The proposed patch fixes this problem, and builds on all OpenJDK
>>> supported platforms.
>>>
>>>  I'd like to thank Bengt Rutisson for the initial review and help
>>> preparing the CR and Webrev.
>>>
>>>  Regards,
>>> Hal
>>
>>
>>
>
>
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