[infinispan-dev] CacheLoaders, Distribution mode and Interceptors

[James Aley]

Hi Ray,

Yeah - I've tried with shared=true/false and preload=true/false. I'm
using org.infinispan.lucene.cachestore.LuceneCacheLoader.

Sorry, I also should have mentioned previously that I'm building from
master, as I need access to the Lucene v4 support.


James.

On 15 March 2013 15:31, Ray Tsang <saturnism at gmail.com> wrote:
> Was the cache loader shared?  Which cache loader were you using?
>
> On Fri, Mar 15, 2013 at 8:03 AM, James Aley <james.aley at swiftkey.net> wrote:
>>
>> Hey all,
>>
>> <OT>
>> Seeing as this is my first post, I wanted to just quickly thank you
>> all for Infinispan. So far I'm really enjoying working with it - great
>> product!
>> </OT>
>>
>> I'm using the InfinispanDirectory for a Lucene project at the moment.
>> We use Lucene directly to build a search product, which has high read
>> requirements and likely very large indexes. I'm hoping to make use of
>> a distribution mode cache to keep the whole index in memory across a
>> cluster of machines (the index will be too big for one server).
>>
>> The problem I'm having is that after loading a filesystem-based Lucene
>> directory into InfinispanDirectory via LuceneCacheLoader, no nodes are
>> retrieving data from the cluster - they instead look up keys in their
>> local CacheLoaders, which involves lots of disk I/O and is very slow.
>> I was hoping to just use the CacheLoader to initialize the caches, but
>> from there on read only from RAM (and network, of course). Is this
>> supported? Maybe I've misunderstood the purpose of the CacheLoader?
>>
>> To explain my observations in a little more detail:
>> * I start a cluster of two servers, using [1] as the cache config.
>> Both have a local copy of the Lucene index that will be loaded into
>> the InfinispanDirectory via the loader. This is a test configuration,
>> where I've set numOwners=1 so that I only need two servers for
>> distribution to happen.
>> * Upon startup, things look good. I see the memory usage of the JVM
>> reflect a pretty near 50/50 split of the data across both servers.
>> Logging indicates both servers are in the cluster view, all seems
>> fine.
>> * When I send a search query to either one of the nodes, I notice the
>> following:
>>   - iotop shows huge (~100MB/s) disk I/O on that node alone from the
>> JVM process.
>>   - no change in network activity between nodes (~300b/s, same as when
>> idle)
>>   - memory usage on the node running the query increases dramatically,
>> and stays higher even after the query is finished.
>>
>> So it seemed to me like each node was favouring use of the CacheLoader
>> to retrieve keys that are not in memory, instead of using the cluster.
>> Does that seem reasonable? Is this the expected behaviour?
>>
>> I started to investigate this by turning on trace logging, in this
>> made me think perhaps the cause was that the CacheLoader's interceptor
>> is higher priority in the chain than the the distribution interceptor?
>> I'm not at all familiar with the design in any level of detail - just
>> what I picked up in the last 24 hours from browsing the code, so I
>> could easily be way off. I've attached the log snippets I thought
>> relevant in [2].
>>
>> Any advice offered much appreciated.
>> Thanks!
>>
>> James.
>>
>>
>> [1] https://www.refheap.com/paste/12531
>> [2] https://www.refheap.com/paste/12543
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