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HBase, mail # user - LRU stats


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Varun Sharma 2013-01-27, 03:05
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Ted Yu 2013-01-27, 05:24
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Re: LRU stats
Varun Sharma 2013-01-27, 09:04
Since i am using only 10 % of allocated cache, I think EvictionThread never
ran - hence, I see the value 0. What's mysterious is who is calling
evictBlock then, because there are non zero evicted blocks ?

On Sat, Jan 26, 2013 at 9:24 PM, Ted Yu <[EMAIL PROTECTED]> wrote:

> Evicted block count stat is gathered in:
>
>   protected long evictBlock(CachedBlock block) {
>
>     map.remove(block.getCacheKey());
>
>     updateSizeMetrics(block, true);
>
>     elements.decrementAndGet();
>
>     stats.evicted();
>
> In EvictionThread#run():
>
>         LruBlockCache cache = this.cache.get();
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>         if(cache == null) break;
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>         cache.evict();
>
> where cache is declared:
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>     private WeakReference<LruBlockCache> cache;
>
> Looks like cache became null (due to heap pressure), leading to 0 evictions
> that you saw.
>
>
> Cheers
>
>
> On Sat, Jan 26, 2013 at 7:05 PM, Varun Sharma <[EMAIL PROTECTED]> wrote:
>
> > Hi,
> >
> > I am running hbase 0.94.3 and I am trying to understand the LRU cache
> stats
> > here:
> >
> > LRU Stats: total=428.75 MB, free=4.05 GB, max=4.46 GB, blocks=35961,
> > accesses=23808283, hits=23098837, hitRatio=97.02%,
> > cachingAccesses=23135166, cachingHits=23066278,
> > cachingHitsRatio=99.70%, *evictions=0,
> > evicted=33211*
> > *
> > *
> > I don't understanding why the number of evictions is 0 - which means that
> > the number of eviction thread runs is 0, AFAIK. Also, I see that 30K
> blocks
> > were evicted - how is that possible ? I have set the hfile evict on close
> > to the default value - which is false - so blocks should not be evicted
> > when hfiles are closed. Where are the evicted blocks coming from when the
> > block is mostly empty and no eviction runs have occured.
> >
> > Thanks
> > Varun
> >
>
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Jean-Daniel Cryans 2013-01-28, 19:27