compatibility issue regarding the active processor count

Xiaobin Lu Xiaobin.Lu at Sun.COM
Wed Oct 1 10:38:02 PDT 2008

How about "-XX:+UseOnlinePsrCountAsActivePsrCount"? Thanks to all for 
the feedbacks.


Daniel D. Daugherty wrote:
> The default should be the correct behavior and the option should
> restore the previous incorrect behavior. The hard part will be
> naming the option. Perhaps:
>    -XX:+UseOnLineProcessorCountAsActiveProcessorCount
> The description could be something like:
>    Restore incorrect active processor count algorithm for
>    backward compatibility.
> Just suggestions...
> Dan
> Xiaobin Lu wrote:
>> Hi folks,
>> I need your opinion about what we should do to solve the 
>> compatibility issue regarding the active processor count. Basically, 
>> the problem is on Solaris, if you create a processor set and then 
>> launch java process without binding to that processor set, the number 
>> of available processors to that java process is the total number of 
>> the online processors minus the number of processors in the processor 
>> set you created. Currently, we just report the total number of the 
>> online processors as the active processor count which is wrong. This 
>> makes the parallel garbage collector to behave in the wrong way (see 
>> bug 6749430 for details) and we need to fix it per request from CBOE.
>> There may be a compatibility issue after we correct this wrong 
>> behavior when someone has already depended on this wrong return, 
>> which we think it might be rare. We definitely need to invent a new 
>> flag in order to address this and the question is whether we should 
>> keep the current behavior as default or not. Personally, I feel we 
>> should have that flag to fall back to the current wrong behavior, but 
>> I might be wrong.
>> Thanks so much in advance for your opinion.
>> -Xiaobin

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