Request for Review (s) - 8133023: ParallelGCThreads is not calculated correctly

David Holmes david.holmes at
Tue Dec 1 06:14:26 UTC 2015

On 1/12/2015 1:04 PM, Kim Barrett wrote:
> On Nov 25, 2015, at 9:11 PM, David Holmes <david.holmes at> wrote:
>> We already have VM_Version::early_initialize() that can/should be used for this if possible.
> VM_Version::early_initialize doesn’t work for this, because
> determine_features (sparc) examines some command-line arguments, and
> those aren't parsed until a later stage of Threads::create_vm.
> Specifically, determine_features (sparc) is presently looking at two
> CLAs: UseV8InstrsOnly (develop) and UseNiagaraInstrs (product).  I
> suspect UseV8InstrsOnly has served its purpose and could be purged.
> But calling determine_features before argument parsing would
> unintentionally ignore UseNiagaraInstrs.
> Calling determine_features from os::init_before_ergo doesn't have this problem.
> [I missed this in my review of Jon’s original change to use early_initialize.]

Thanks Kim. Still makes me wonder if it isn't something else that is in 
the wrong place - the initialization dance is very tricky and I hate to 
see yet-another-vm-version-init function added. Makes me wonder whether 
determine_features should only look at what the hardware provides, and 
then after argument processing is complete (or appropriate portion 
thereof) we update the features that should actually be used? - but that 
ship sailed long ago.



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