[infinispan-dev] Eviction maxEntries analysis

[Martin Gencur]

On Mon, 2012-02-06 at 06:22 -0500, Mircea Markus wrote:
> That was my understanding as well.

Yeah, the first number is for LRU. I initially encountered this behavior
with EDG so I tried also with ISPN and created
https://issues.jboss.org/browse/ISPN-1822 . I was about to close it as
"Rejected" or so but now I don't know:)

The fact is that there will be rarely such a use case with just a few
entries in a cache. So I don't know if this is worth investigating.

Martin

> 
> ----- Original Message -----
> From: "Galder Zamarreño" <galder at redhat.com>
> To: "infinispan -Dev List" <infinispan-dev at lists.jboss.org>
> Sent: Monday, February 6, 2012 9:57:20 AM
> Subject: Re: [infinispan-dev] Eviction maxEntries analysis
> 
> Vladimir, I had understood that with the new eviction logic, the only possible case is that the cache was evicted *before* maxEntries was reached cos eviction happened at the segment level.
> 
> However, I'd have never expected for the cache to grow beyon its size. If that's the case, I think that'd be a bug.
> 
> @Martin, what I don't understand about the figures below is what algorithm is used with IBM JDK. Is that LRU and LIRS for the numbers in parenthesis? If so, maybe a bug in LRU with IBM JDKs?
> 
> Cheers,
> 
> On Feb 3, 2012, at 6:17 PM, Vladimir Blagojevic wrote:
> 
> > Martin,
> > 
> > There will always be "problems" around sizing in these small containers. 
> > I think we are all aware of it now, what is more important is that 
> > eviction works properly in all other scenarios! I am ok with this!
> > 
> > Regards,
> > Vladimir
> > 
> > On 12-02-03 11:59 AM, Martin Gencur wrote:
> >> I see, for the bigger numbers entries are evicted (more than just to
> >> decrease the number to maxEntries) before I actually check the number so
> >> this is expected. For the 2,4,6,8,10 eviction did not run so the cache
> >> contains more than maxEntries. Are we OK with that?
> >> 
> >> Thanks
> >> 
> >> 
> >> M.
> >> 
> >> 
> >> On Fri, 2012-02-03 at 15:29 +0100, Martin Gencur wrote:
> >>> Hi all,
> >>> I ran a few tests to find out what is the actual number of entries held
> >>> in a cache when certain "maxEntries" param is set for eviction and I
> >>> store more than maxEntries entries. I tested with HotSpot JDK6 [1], IBM
> >>> JDK 6,7 [2]. OpenJDK6 seems to have the same results as HotSpot JDK.
> >>> 
> >>> Results:
> >>> 
> >>> maxEntries being set ->  actual number of entries held in the cache
> >>> 
> >>> HotSpot JDK:
> >>> ------------
> >>> 
> >>> 2 ->  2
> >>> 4 ->  4
> >>> 6 ->  4
> >>> 8 ->  8
> >>> 10 ->  8
> >>> 256 ->  232
> >>> 300 ->  266
> >>> 
> >>> IBM JDK (both 6, 7):
> >>> --------------------
> >>> 
> >>> 2 ->  4 (2 with LIRS)
> >>> 4 ->  6 (4 with LIRS)
> >>> 6 ->  10
> >>> 8 ->  11 (8 with LIRS)
> >>> 10 ->  13, (8 with LIRS)
> >>> 300 ->  287, (266 with LIRS)
> >>> 256 ->  247, (232 with LIRS)
> >>> 
> >>> I modified one test in ispn-core to do this testing:
> >>> https://github.com/mgencur/infinispan/commit/837a1c752fa7fbfb3f05738dd873e78cbf71d071
> >>> 
> >>> 
> >>> 
> >>> Any thoughts ? :)
> >>> 
> >>> 
> >>> 
> >>> [1]
> >>> 
> >>> java version "1.6.0_21"
> >>> Java(TM) SE Runtime Environment (build 1.6.0_21-b06)
> >>> Java HotSpot(TM) 64-Bit Server VM (build 17.0-b16, mixed mode)
> >>> 
> >>> [2]
> >>> 
> >>> java version "1.6.0"
> >>> Java(TM) SE Runtime Environment (build pxi3260sr9fp1-20110208_03(SR9
> >>> FP1))
> >>> IBM J9 VM (build 2.4, JRE 1.6.0 IBM J9 2.4 Linux x86-32
> >>> jvmxi3260sr9-20110203_74623 (JIT enabled, AOT enabled)
> >>> 
> >>> java version "1.7.0"
> >>> Java(TM) SE Runtime Environment (build pxi3270-20110827_01)
> >>> IBM J9 VM (build 2.6, JRE 1.7.0 Linux x86-32 20110810_88604 (JIT
> >>> enabled, AOT enabled)
> >>> 
> >>> 
> >>> 
> > 
> > _______________________________________________
> > infinispan-dev mailing list
> > infinispan-dev at lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/infinispan-dev
> 
> --
> Galder Zamarreño
> Sr. Software Engineer
> Infinispan, JBoss Cache
> 
> 
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-- 
Martin Gencur
--
JBoss QE, Enterprise Data Grid
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