James, to workaround ISPN-2938 you could use preloading=true on the "lucene-index" cacheloader, and preloading="false" on the "lucene-metadata" cacheloader. Not particularly critical, but would save you a bunch of memory.
Sanne On 19 March 2013 14:12, Sanne Grinovero <sa...@infinispan.org> wrote: > Mircea, > what I was most looking forward was to you comment on the interceptor > order generated for DIST+cachestores > - we don't think the ClusteredCacheLoader should be needed at all > - each DIST node is loading from the CacheLoader (any) rather than > loading from its peer nodes for non-owned entries (!!) > > This has come up on several threads now and I think it's critically > wrong, as I commented previously this also introduces many > inconsistencies - as far as I understand it. > > BTW your gist wouldn't work, the metadata cache needs to load certain > elements too. But nice you spotted the need to potentially filter what > "preload" means in the scope of each cache, as the metadata one should > only preload metadata, while in the original configuration this data > would indeed be duplicated. > Opened: https://issues.jboss.org/browse/ISPN-2938 > > Sanne > > On 19 March 2013 11:51, Mircea Markus <mmar...@redhat.com> wrote: >> >> On 16 Mar 2013, at 01:19, Sanne Grinovero wrote: >> >>> Hi Adrian, >>> let's forget about Lucene details and focus on DIST. >>> With numOwners=1 and having two nodes the entries should be stored >>> roughly 50% on each node, I see nothing wrong with that >>> considering you don't need data failover in a read-only use case >>> having all the index available in the shared CacheLoader. >>> >>> In such a scenario, and having both nodes preloaded all data, in case >>> of a get() operation I would expect >>> either: >>> A) to be the owner, hence retrieve the value from local in-JVM reference >>> B) to not be the owner, so to forward the request to the other node >>> having roughly 50% chance per key to be in case A or B. >>> >>> But when hitting case B) it seems that instead of loading from the >>> other node, it hits the CacheLoader to fetch the value. >>> >>> I already had asked James to verify with 4 nodes and numOwners=2, the >>> result is the same so I suggested him to ask here; >>> BTW I think numOwners=1 is perfectly valid and should work as with >>> numOwners=1, the only reason I asked him to repeat >>> the test is that we don't have much tests on the numOwners=1 case and >>> I was assuming there might be some (wrong) assumptions >>> affecting this. >>> >>> Note that this is not "just" a critical performance problem but I'm >>> also suspecting it could provide inconsistent reads, in two classes of >>> problems: >>> >>> # non-shared CacheStore with stale entries >>> If for non-owned keys it will hit the local CacheStore first, where >>> you might expect to not find anything, so to forward the request to >>> the right node. What if this node has been the owner in the past? It >>> might have an old entry locally stored, which would be returned >>> instead of the correct value which is owned on a different node. >>> >>> # shared CacheStore using write-behind >>> When using an async CacheStore by definition the content of the >>> CacheStore is not trustworthy if you don't check on the owner first >>> for entries in memory. >>> >>> Both seem critical to me, but the performance impact is really bad too. >>> >>> I hoped to make some more tests myself but couldn't look at this yet, >>> any help from the core team would be appreciated. >> I think you have a fair point and reads/writes to the data should be >> coordinated through its owners both for performance and (more importantly) >> correctness. >> Mind creating a JIRA for this? >> >>> >>> @Ray, thanks for mentioning the ClusterCacheLoader. Wasn't there >>> someone else with a CacheLoader issue recently who had worked around >>> the problem by using a ClusterCacheLoader ? >>> Do you remember what the scenario was? >>> >>> Cheers, >>> Sanne >>> >>> On 15 March 2013 15:44, Adrian Nistor <anis...@redhat.com> wrote: >>>> Hi James, >>>> >>>> I'm not an expert on InfinispanDirectory but I've noticed in [1] that >>>> the lucene-index cache is distributed with numOwners = 1. That means >>>> each cache entry is owned by just one cluster node and there's nowhere >>>> else to go in the cluster if the key is not available in local memory, >>>> thus it needs fetching from the cache store. This can be solved with >>>> numOwners > 1. >>>> Please let me know if this solves your problem. >>>> >>>> Cheers! >>>> >>>> On 03/15/2013 05:03 PM, James Aley 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 >>>>> _______________________________________________ >>>>> infinispan-dev mailing list >>>>> infinispan-dev@lists.jboss.org >>>>> https://lists.jboss.org/mailman/listinfo/infinispan-dev >>>> >>>> _______________________________________________ >>>> infinispan-dev mailing list >>>> infinispan-dev@lists.jboss.org >>>> https://lists.jboss.org/mailman/listinfo/infinispan-dev >>> _______________________________________________ >>> infinispan-dev mailing list >>> infinispan-dev@lists.jboss.org >>> https://lists.jboss.org/mailman/listinfo/infinispan-dev >> >> Cheers, >> -- >> Mircea Markus >> Infinispan lead (www.infinispan.org) >> >> >> >> >> >> _______________________________________________ >> infinispan-dev mailing list >> infinispan-dev@lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/infinispan-dev _______________________________________________ infinispan-dev mailing list infinispan-dev@lists.jboss.org https://lists.jboss.org/mailman/listinfo/infinispan-dev