compatibility issue regarding the active processor count

Xiaobin Lu Xiaobin.Lu at Sun.COM
Mon Oct 6 16:06:59 PDT 2008

According to the discussion with Paul and others, we decided to drop the 
flag completely. The main reason is that the current behavior is so bad 
that no one is going to be using it anyway. They may have already used 
ParallelGCThreads to get around it. Plus, we have some reservation about 
adding another long option name to the existing pool which has already 
grown so big.


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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