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From Atri Sharma <atri.j...@gmail.com>
Subject Re: TTL-based expirations
Date Mon, 13 Apr 2015 05:41:29 GMT
Out of curiosity, did we never face thrashing with this approach? (assuming
wild workloads that hit the same page again and again)

On Mon, Apr 13, 2015 at 7:35 AM, Dmitriy Setrakyan <dsetrakyan@gridgain.com>

> Guys,
> I have been playing with TTL-based expirations for streaming and am
> noticing that often the TTL thread cannot cope with the load a
> data-streamer can generate.
> Our current approach for TTL is implemented with a thread that keeps all
> cache entries in sorted-by-expire-time order and scans this ordered list
> every time something expires. The scan is optimized, such that once an
> entry that does not need to expire yet is touched, the thread goes into
> wait mode until TTL time for that entry expires. However even with this
> optimization, this thread cannot expire the entries fast enough.
> I think if we handle TTL expirations the same way as we handle evictions,
> through eviction policies, this problem would go away, because all the
> threads that add entries to eviction queue are also responsible to evict
> the excess entries as well.
> I have created a parent ticket for this issue:
> https://issues.apache.org/jira/browse/IGNITE-729
> Would be nice to implement them in the next couple of weeks.
> D.



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