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From Kevin Burton <bur...@spinn3r.com>
Subject Re: Using chronicle map to store off heap data easily
Date Fri, 20 Mar 2015 16:08:21 GMT
I agree 110%.

Chronicle also works with memory.  ChronicleMapBuilder

create
> <http://openhft.github.io/Chronicle-Map/apidocs/net/openhft/chronicle/map/ChronicleMapBuilder.html#create-->
> ()
> Creates a new hash container, storing it's data in off-heap memory, not
> mapped to any file.


I assume internally they’re using mmap data.  DirectByteBuffers and
ByteBuffers are mmap() backed.  You can also do this via unsafe or with JNI.


On Fri, Mar 20, 2015 at 5:46 AM, Tim Bain <tbain@alumni.duke.edu> wrote:

> We run on VMs where even "local" disk is on a SAN, so anything that stays
> in memory (i.e. ConcurrentHashMap) will be faster than anything that gets
> written to disk (i.e. ChronicleHashMap), even if it eliminates garbage
> collection.  So this isn't a drop-in replacement we'd welcome unless it was
> configurable for which one to use.
>
> Tim
> On Mar 20, 2015 12:17 AM, "Kevin Burton" <burton@spinn3r.com> wrote:
>
> > This is interesting.
> >
> > Right now AMQ5 uses ConcurrentHashMap and for large heaps this has some
> > obvious GC issues.
> >
> > 1.  You have to keep a LARGE % of the JVM memory free for large GCs.
> >
> > 2.  All the objects pool into the old generation screwing up GC and
> wasting
> > cycles for every GC.
> >
> > Then there’s this.
> >
> >
> >
> http://www.javacodegeeks.com/2015/03/creating-millions-of-objects-with-zero-garbage.html
> >
> >
> http://openhft.github.io/Chronicle-Map/apidocs/net/openhft/chronicle/map/ChronicleMapBuilder.html
> >
> > This should allow a drop in replacement for CHMs with off-heap memory.
> >
> > --
> >
> > Founder/CEO Spinn3r.com
> > Location: *San Francisco, CA*
> > blog: http://burtonator.wordpress.com
> > … or check out my Google+ profile
> > <https://plus.google.com/102718274791889610666/posts>
> > <http://spinn3r.com>
> >
>



-- 

Founder/CEO Spinn3r.com
Location: *San Francisco, CA*
blog: http://burtonator.wordpress.com
… or check out my Google+ profile
<https://plus.google.com/102718274791889610666/posts>
<http://spinn3r.com>

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