RFR(s): 8152160: SIGFPE in CompactibleFreeListSpaceLAB::compute_desired_plab_size

Per Liden per.liden at oracle.com
Tue Mar 22 18:38:09 UTC 2016


> On 22 Mar 2016, at 18:19, sangheon <sangheon.kim at oracle.com> wrote:
> 
> Hi Per,
> 
> Thank you for reviewing this issue.
> 
> On 03/22/2016 08:59 AM, Per Liden wrote:
>> Hi Sangheon,
>> 
>> On 2016-03-22 03:12, sangheon wrote:
>>> Hi all,
>>> 
>>> Could I have a couple of reviews for this change?
>>> 
>>> With large value of CMSOldPLABNumRefills, SIGFPE would happen at
>>> CompactibleFreeListSpaceLAB::compute_desired_plab_size() because related
>>> routine would be zero by an overflow.
>>> 
>>> Type-casting to 'double' before the problematic division will resolve
>>> the problem.
>> 
>> Casting to double doesn't quite seem like the right thing to do here. Can't this be rephrased to avoid the overflow completely, something like:
>> 
>> _global_num_blocks[i] / _global_num_workers[i] / CMSOldPLABNumRefills
> You are right!
> I like this much more.
> 
> Webrev: http://cr.openjdk.java.net/~sangheki/8152160/webrev.01 <http://cr.openjdk.java.net/~sangheki/8152160/webrev.01>
> 

Looks good.

Per


> Sangheon
> 
>> 
>> cheers,
>> Per
>> 
>>> 
>>> CR: https://bugs.openjdk.java.net/browse/JDK-8152160 <https://bugs.openjdk.java.net/browse/JDK-8152160>
>>> Webrev: http://cr.openjdk.java.net/~sangheki/8152160/webrev.00 <http://cr.openjdk.java.net/~sangheki/8152160/webrev.00>
>>> Testing: JPRT, TestOptionsWithRanges.java via RBT and manual test as CR
>>> description.
>>> 
>>> Thanks,
>>> Sangheon

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