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
fccfg.setReadThrough(true);
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.
[1]
https://github.com/apache/ignite/blob/b3d347e35a254928fd1c4a0473f1b17d642c72f3/modules/core/src/main/java/org/apache/ignite/internal/processors/cache/store/GridCacheWriteBehindStore.java
--
Denis
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..)
--
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