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From Denis Magda <dma...@gridgain.com>
Subject Re: Cache inserts in full offheap
Date Fri, 05 Feb 2016 13:51:30 GMT
Eviction of entries doesn't trigger flushing of data from the 
write-behind store [1] to your disk storage.
The write-behind store flushes data basing on flush frequency and its 
internal queue size.

Actually, when you put an entry its copy will be stored in offheap and 
in the write-behind store internal queue.
When an entry is evicted from the offheap cache it's not completely lost 
in your case because either write-behind store's queue or your disk 
storage already has it.

You don't see any file on your disk because the write-behind store's 
queue size is enough to hold all the entries. When you get an entry that 
is already evicted it's taken from the write-behind queue, placed back 
to memory and returned to your application.

If you remove this from your configuration

then you will see that some entries are already evicted because you will 
get 'null' instead of their real values.

Write-behind queue size can be controlled with 'setFlushSize' parameter.



On 2/5/2016 4:01 PM, bsmets wrote:
> Hi,
> We don't use any Near caches. You can find our configuration on this gist:
> https://gist.github.com/anonymous/ebfa88893764f8a3a5f8
> Note that we know that these settings are ridiculous for any serious
> production environment but we are just interested in what happens when the
> offheap gets filled up. We would expect to see the entries that are being
> evicted to be written to disk (bypassing the writebehind settings) so they
> don't get lost when they get evicted as they have no where else to go (swap
> disabled). However, we observed that no files are getting written to disk,
> the cache contains only the last X offheap entries with others evicted BUT
> all entries are still accessible and can be retrieved just fine. Maybe this
> is just a weird case of luck with memory not being cleared yet? (Although
> this experiment is repeatable with the same result every time..)
> --
> View this message in context: http://apache-ignite-users.70518.x6.nabble.com/Cache-inserts-in-full-offheap-tp2851p2858.html
> Sent from the Apache Ignite Users mailing list archive at Nabble.com.

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