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From "Raffaele P. Guidi" <>
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
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 ;).


On Fri, Jan 20, 2012 at 8:49 AM, Andy <> 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 <>
> *To:*; Andy <>
> *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" <> 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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