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From "Raffaele P. Guidi" <raffaele.p.gu...@gmail.com>
Subject Re: Status of DirectMemory
Date Fri, 20 Jan 2012 09:54:05 GMT
It of course has the chance to specify a limit (well, you choose how many
blocks up to 2gb you want to allocate) but we abandoned the multi tiered
hierarchy to focus on the core offering (off-heap memory, of course) and we
are working on integration with Apache JCS to provide this feature (still
work in progress, though).

Regarding performance comparisons: of course a heap cache is faster below a
certain memory limit (it doesn't need serialization) - but directmemory can
catch up fast when it comes to multi-gb caches (because heap means garbage
collection - and GC pauses can be pretty heavy in these scenarios). You can
find out more about this in my blog
http://raffaeleguidi.wordpress.com/2011/01/12/directmemory-benchmark-heap-vs-off-heap-vs-orientdb/.
No direct benchmark against ehcache has been done, yet, and it probably is
not correct at all - it should be done against their BigMemory, instead;
beware the apples vs oranges syndrome ;).

Ciao,
    R

On Fri, Jan 20, 2012 at 8:49 AM, Andy <angelflow@yahoo.com> wrote:

> Thanks.
>
> - Does DM let me specify a cache size limit? Say I want to devote 6GB to
> cache, and when that limit is reached, expired cached items will be
> automatically evicted first, after that cached will be evicted based on
> LRU. Does DM support something like that?
>
> - Does DM support a tiered cache hierarchy? For example, 2GB will be
> cached on heap, beyond that there's 6GB off-heap cache
>
> - How is DM's performance compared to ehcache? How many sets and gets can
> it do per second?
>
> Appreciate your help
> Andy
>
>   ------------------------------
> *From:* Raffaele P. Guidi <raffaele.p.guidi@gmail.com>
> *To:* directmemory-user@incubator.apache.org; Andy <angelflow@yahoo.com>
> *Sent:* Friday, January 20, 2012 2:02 AM
> *Subject:* Re: Status of DirectMemory
>
> I would say it is ready to be tested :) also, you should consider it if
> you need a multi-gb of cache but consider that objects in DM are
> (transparently) serialized, so you can't call their methods or read their
> properties until you retrieve them. If this fits your use case then
> DirectMemory is right for you (and we are here to help).
> Cheers,
>      Raffaele
> Il giorno 20/gen/2012 07:47, "Andy" <angelflow@yahoo.com> ha scritto:
>
> Hi,
>
> Is DirectMemory ready for production? If not, is there any estimated
> timeline?
>
> Also, at what point should I move from on-heap to off-heap cache? 4GB of
> cached data? 10GB? 20GB? Any rules of thumb there?
>
> Thank you.
>
> Andy
>
>
>
>

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