RFR: [8u] OOME in SurrogateLockerThread deadlocks the GC cycle

[Aleksey Shipilev]

On 10/03/2017 02:52 PM, Roman Kennke wrote:
> Am 03.10.2017 um 14:43 schrieb Aleksey Shipilev:
>> On 10/03/2017 12:06 PM, Roman Kennke wrote:
>>> Looks good.
>>> It probably makes sense to evac the pll even before the root processor parallelizes root evac?
>> Maybe, maybe not? Current placement guarantees first evac, and keeps the root evacuation code in
>> common place, and keeps patch at bare minimum. I like that two last parts about it.

> It doesn't exactly guarantee first evac, it just makes it more likely. There might well be one or
> more worker threads getting scheduled ahead of the one that evacs the pll. 

Yes, and it would also go via the path that tries to evac the PLL. So every thread would try to evac
PLL the first thing, pushing scheduling out of equation. At least that was the intent :)

> That's why I proposed to maybe even explictely evac the pll from the VMThread, even before we
> spin up the workers. But this might well be overkill (considering the other parts of the fix that
> already ensure smooth handling in case of failure). I leave the decision up to you :-)
Yeah, seems like overkill. Well, current thing is also overkill, but more concise one, and it is
gone in 9 and 10 anyway. I looked through the places where process_evacuate_roots is called, and
there are exceptional paths that also need to be taken care of. Leaving PLL evac inside
ShenandoahRootEvacuator seems less messy.

-Aleksey