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From Andy <angelf...@yahoo.com>
Subject Re: Status of DirectMemory
Date Fri, 20 Jan 2012 10:50:46 GMT
> you choose how many blocks up to 2gb you want to allocate

What happens if I want to cache more than 2GB?


> 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/

I'm looking at the 1st graph. According to that graph, for off-heap cache, put/get 100K entries
takes 100 seconds. That's about 1,000 GET/PUT per second. Did I interpret the data correctly?
That seems very slow for an in-process in-memory cache. I can get much higher performance
than that using memcached or redis over the network.

Thanks.
Andy


________________________________
 From: Raffaele P. Guidi <raffaele.p.guidi@gmail.com>
To: Andy <angelflow@yahoo.com> 
Cc: "directmemory-user@incubator.apache.org" <directmemory-user@incubator.apache.org>

Sent: Friday, January 20, 2012 4:54 AM
Subject: Re: Status of DirectMemory
 

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 helpAndy
>
>
>
>________________________________
> 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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