RFR: Clear outgoing matrix for root regions during preparation phase

Zhengyu Gu zgu at redhat.com
Wed Mar 22 15:48:35 UTC 2017

Got it.



On 03/22/2017 11:44 AM, Roman Kennke wrote:
> Good question. I don't think so, because we'd be messing with the matrix
> for regions we're likely to look at. While it probably wouldn't clash, I
> find it easier to convince myself if it happens in a separate pass.
> That's why I hooked it up on the last pass.
> Roman
> Am 22.03.2017 um 16:35 schrieb Zhengyu Gu:
>> Would it be better to the clear outbound matrix during building the
>> root set?
>> -Zhengyu
>> On 03/22/2017 11:16 AM, Roman Kennke wrote:
>>> We're currently clearing the outgoing matrix for root regions during the
>>> collection phase of partial GC. I find it more natural to do it in the
>>> preparation phase. While it's not per-se incorrect (only one thread
>>> should have to do with each root region at a time), I'm a bit uneasy to
>>> have threads clearing whole rows, while other threads are updating the
>>> matrix. They *should* not collide, but I'll sleep better if we could
>>> just do it during preparation. It also means to move verification up
>>> before preparation, because otherwise whole rows will be cleared.
>>> http://cr.openjdk.java.net/~rkennke/cleanmatrix/webrev.00/
>>> <http://cr.openjdk.java.net/%7Erkennke/cleanmatrix/webrev.00/>
>>> Roman

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