RFR 8230162: ScopeImpl.remove() has O(N) performance

[Brad Corso]

Friendly ping.

On Wed, Sep 18, 2019 at 9:55 AM Brad Corso <bcorso at google.com> wrote:

> Hi Jan,
>
> I'm okay with either version so I'll leave that decision up to you.
>
> Let me know if there's anything else you need from me.
>
> Thanks!
> Brad
>
> On Wed, Sep 18, 2019 at 12:38 AM Jan Lahoda <jan.lahoda at oracle.com> wrote:
>
>> I've added logging to count how many Entries are created, and there's a
>> little above 500000 instances created for java.base and a little less
>> for java.desktop. So if the Entry would be 8 bytes bigger, it would be
>> about 4MB, which does not sound terrible. So maybe we should go with
>> version .00.
>>
>> Jan
>>
>> On 18. 09. 19 3:10, Brad Corso wrote:
>> > Hi Jan, are you okay moving forward with
>> > http://cr.openjdk.java.net/~ronsh/8230162/webrev.01/?
>> >
>> > On Wed, Sep 4, 2019 at 5:15 AM Ron Shapiro <ronshapiro at google.com
>> > <mailto:ronshapiro at google.com>> wrote:
>> >
>> >     Here's the updated webrev that Brad mentioned in his last message:
>> >     http://cr.openjdk.java.net/~ronsh/8230162/webrev.01/
>> >
>> >     On Wed, Aug 28, 2019 at 2:40 AM Brad Corso <bcorso at google.com
>> >     <mailto:bcorso at google.com>> wrote:
>> >
>> >             I believe "Do you have any estimates of the increase in size
>> >             in typical
>> >             usage, due to the extra field in Scope?" (Jon)
>> >
>> >         I was seeing noticeably bad performance once the size of the
>> >         Entry.sibling linked list reached ~10000, and the max I saw was
>> >         ~30000 in a single scope. Given that an additional reference
>> >         adds 32/64b, this could add up to 120/240Kb for the cases I saw.
>> >
>> >             I'd add, is there a chance to get an improvement in
>> >             Scope.remove speed
>> >             without making ScopeImpl.Entry bigger (assuming it gets
>> >             bigger(?))? One
>> >             possibility that occurred to me is that we could try not to
>> >             remove the
>> >             things from elems, but only mark them as removed. We would
>> >             need to do
>> >             filtering (and possibly the actual removal) while reading
>> >             from the Scope
>> >             (in getSymbols), so this is a different kind of trade-off.
>> >
>> >             (Overall, I guess the question is whether we are trading
>> >             problems with
>> >
>> >             Scope.remove speed in some cases for out-of-memory problems
>> >             in other cases.)
>> >
>> >         Thanks, I've verified your suggestion also gives us the
>> >         performance improvements, so this change is okay with me.
>> >
>> >
>> >
>> >         On Tue, Aug 27, 2019 at 12:05 AM Jan Lahoda
>> >         <jan.lahoda at oracle.com <mailto:jan.lahoda at oracle.com>> wrote:
>> >
>> >             On 27. 08. 19 0:06, Brad Corso wrote:
>> >              > Sorry, what's the question?
>> >
>> >             I believe "Do you have any estimates of the increase in size
>> >             in typical
>> >             usage, due to the extra field in Scope?" (Jon)
>> >
>> >             I'd add, is there a chance to get an improvement in
>> >             Scope.remove speed
>> >             without making ScopeImpl.Entry bigger (assuming it gets
>> >             bigger(?))? One
>> >             possibility that occurred to me is that we could try not to
>> >             remove the
>> >             things from elems, but only mark them as removed. We would
>> >             need to do
>> >             filtering (and possibly the actual removal) while reading
>> >             from the Scope
>> >             (in getSymbols), so this is a different kind of trade-off.
>> >
>> >             (Overall, I guess the question is whether we are trading
>> >             problems with
>> >             Scope.remove speed in some cases for out-of-memory problems
>> >             in other cases.)
>> >
>> >             Jan
>> >
>> >              >
>> >              > On Mon, Aug 26, 2019 at 1:54 PM Ron Shapiro
>> >             <ronshapiro at google.com <mailto:ronshapiro at google.com>
>> >              > <mailto:ronshapiro at google.com
>> >             <mailto:ronshapiro at google.com>>> wrote:
>> >              >
>> >              >     Adding Brad back in to the thread since he would know
>> >             best
>> >              >
>> >              >     בתאריך יום ב׳, 26 באוג׳ 2019, 19:40, מאת Jonathan
>> Gibbons
>> >              >     ‏<jonathan.gibbons at oracle.com
>> >             <mailto:jonathan.gibbons at oracle.com>
>> >             <mailto:jonathan.gibbons at oracle.com
>> >             <mailto:jonathan.gibbons at oracle.com>>>:
>> >              >
>> >              >
>> >              >         On 8/26/19 9:12 AM, Ron Shapiro wrote:
>> >              >          >
>> >              >          > Note that the patch was prepared by my
>> >             coworker, Brad (cc'd).
>> >              >         I wasn't
>> >              >          > sure what to do to make sure that he was
>> >             attributed correctly.
>> >              >
>> >              >
>> >              >         Mention this when you have a sponsor to push the
>> >             changeset, so
>> >              >         that it
>> >              >         can be marked with "Contributed-By:"
>> >              >
>> >              >         -- Jon
>> >              >
>> >
>>
>
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