Thanks Vladislav

From: Vladislav Pyatkov [mailto:vldpyat...@gmail.com]
Sent: Wednesday, October 26, 2016 5:08 AM
To: user@ignite.apache.org
Subject: Re: Evicted entry appears in Write-behind cache

Hi,

Yes, write behind buffer gets locks on entries which stores between loading to 
CacheStore. So that this entries cannot be evicted.

If "get" invocation can not find value in cache, it will try to get value from 
CacheStore.

On Fri, Oct 14, 2016 at 6:55 PM, Pradeep Badiger 
<pradeepbadi...@fico.com<mailto:pradeepbadi...@fico.com>> wrote:
I have some log statements in the load() which gets called when there is no 
entry in the cache or write behind buffer. What I learnt is that there is a 
write behind buffer that holds on to the entries (even the evicted ones) and 
whenever there is a get() for an entry, ignite looks at both the cache and the 
write behind buffer and loads it. If it doesn’t find it in any of the two, it 
then uses the read through mechanism to load the entry from the store.

Thanks,
Pradeep V.B.

From: Vladislav Pyatkov 
[mailto:vpyat...@gridgain.com<mailto:vpyat...@gridgain.com>]
Sent: Friday, October 14, 2016 4:25 AM

To: user@ignite.apache.org<mailto:user@ignite.apache.org>
Subject: Re: Evicted entry appears in Write-behind cache

Hi Paradeep,

Why are you think, what the entry could not be read through your persistence 
storage:

.setReadThrough(stateQoS.isReadThroughEnabled())

When cache can not get data from in memory, it will try to get data from 
storage, which configured as "ReadThrough".

On Thu, Oct 13, 2016 at 6:41 PM, Pradeep Badiger 
<pradeepbadi...@fico.com<mailto:pradeepbadi...@fico.com>> wrote:
Hi Vladislav,

Please see the below cache configuration.

                                             LruEvictionPolicy evictionPolicy = 
new LruEvictionPolicy<>(getIntProperty(envConfig, CACHE_SIZE, 10000));
                                             cacheConfiguration
                                                            
.setEvictionPolicy(evictionPolicy)
                                                            
.setWriteBehindFlushSize(getIntProperty(envConfig, CACHE_WB_FLUSH_SIZE, 0))
                                                            
.setWriteBehindBatchSize(getIntProperty(envConfig, CACHE_WB_BATCH_SIZE, 200))
                                                            
.setWriteBehindEnabled(stateQoS.isWriteBehindEnabled())
                                                            
.setWriteBehindFlushFrequency(getIntProperty(envConfig, CACHE_WB_FLUSH_FREQ_MS, 
5000))
                                                            
.setWriteBehindFlushThreadCount(getIntProperty(envConfig, 
CACHE_WB_FLUSH_THREADS, 10))
                                                            
.setCacheStoreFactory(new StateCacheStoreFactory<K, V>(cacheName,
                                                                                
          storageManager))
                                                            .setName(cacheName)
                                                            
.setReadThrough(stateQoS.isReadThroughEnabled())
                                                            
.setWriteThrough(stateQoS.isWriteThroughEnabled());

Thanks,
Pradeep V.B.

From: Vladislav Pyatkov 
[mailto:vldpyat...@gmail.com<mailto:vldpyat...@gmail.com>]
Sent: Wednesday, October 12, 2016 2:59 AM

To: user@ignite.apache.org<mailto:user@ignite.apache.org>
Subject: Re: Evicted entry appears in Write-behind cache

Hi Pradeep,

Could you please provide cache configuration?

On Tue, Oct 11, 2016 at 6:57 PM, Denis Magda 
<dma...@gridgain.com<mailto:dma...@gridgain.com>> wrote:
Looks like that my initial understanding was wrong. There is a related 
discussion
http://apache-ignite-users.70518.x6.nabble.com/Cache-read-through-with-expiry-policy-td2521.html

—
Denis

On Oct 11, 2016, at 8:55 AM, Pradeep Badiger 
<pradeepbadi...@fico.com<mailto:pradeepbadi...@fico.com>> wrote:

Hi Denis,

I did the get() on the evicted entry from the cache, it still returned me the 
value without calling the load() on the store. As you said, the entry would be 
cached in the write behind store even for the evicted entry. Is that true?

Thanks,
Pradeep V.B.
From: Denis Magda [mailto:dma...@gridgain.com]
Sent: Monday, October 10, 2016 9:13 PM
To: user@ignite.apache.org<mailto:user@ignite.apache.org>
Subject: Re: Evicted entry appears in Write-behind cache

Hi,

How do you see that the evicted entries are still in the cache? If you check 
this by calling cache get like operations then entries can be loaded back from 
the write-behind store or from your underlying store.

—
Denis

On Oct 8, 2016, at 1:00 PM, Pradeep Badiger 
<pradeepbadi...@fico.com<mailto:pradeepbadi...@fico.com>> wrote:

Hi,

I am trying to evaluate Apache Ignite and trying to explore eviction policy and 
write behind features. I am seeing that whenever a cache is configured with 
eviction policy and write behind feature, the write behind cache always have 
all the changed entries including the ones that are evicted, before the write 
cache is flushed. But soon after it is flushed, the store loads again from DB. 
Is this the expected behavior? Is there a documentation on how the write behind 
cache works?

Thanks,
Pradeep V.B.
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