[infinispan-dev] Question about replication with 5.2.0.CR1

Tue Jan 15 08:45:21 EST 2013

I logged this as https://issues.jboss.org/browse/ISPN-2712

On Jan 15, 2013, at 7:44 AM, Randall Hauch <rhauch at redhat.com> wrote:

> I would tend to say that it does not behave like it is passivating some of the data, because some of the entries are simply missing in the second process after startup completes. In other words, we call "get" with a key that was clearly transferred, but we get null back.
> 
> My understanding of passivation is that the entry will be *either* in-memory or persisted in the cache store (but not both). It appears in our tests that while most entries were added to the cache store (of the second process), some do not exist in the cache store *or* in-memory.
> 
> On Jan 14, 2013, at 4:19 PM, Ray Tsang <saturnism at gmail.com> wrote:
> 
>> Does it behave like what's described here? https://docs.jboss.org/author/display/ISPN/Cache+Loaders+and+Stores#CacheLoadersandStores-CachePassivation
>> 
>> Thanks,
>> 
>> On Mon, Jan 14, 2013 at 6:53 AM, Randall Hauch <rhauch at redhat.com> wrote:
>> We're using MODE-1745 to track this problem (from ModeShape's perspective): https://issues.jboss.org/browse/MODE-1745
>> 
>> Here's an update.
>> 
>> After some more extensive debugging sessions, found the following in the scenario when the 2nd cluster nodes is started only after the first clustered node has completed initialization:
>> 
>>         • state transfer seems to be sending all the data across to node 2 from node 1 - in total 293 PutKeyValueCommand
>>         • when the systemNode == null check is performed on node 2, the cache only has 222 entries and there is nothing persisted in the file cache store
>> 
>> This seems to be a case of nodes being evicted from node 2, without being persisted on the underlying cache store. Disabling eviction via the configuration file make this scenario pass. With the latter set to NONE, all the 293 entries received by node 2 are placed in the data container. With the eviction set to
>> 
>>         <eviction strategy="LIRS" maxEntries="1000"/>
>> 
>> only 222 entries (out of 293 total) are placed in the cache. This indicates to Horia and I that there's a possible bug aroundorg.infinispan.container.DefaultDataContainer#put /org.infinispan.util.concurrent.BoundedConcurrentHashMap (the actual runtime instance) and eviction.
>> 
>> Running with:
>> 
>>         <eviction strategy="LRU" maxEntries="10000"/>
>> 
>> produces the same problem, so ATM we're able to run successfully **ONLY** with eviction disabled.
>> 
>> Can someone familiar with Infinispan's internals please take a look at this to see if we're correct?
>> 
>> 
>> On Jan 11, 2013, at 12:03 PM, Randall Hauch <rhauch at redhat.com> wrote:
>> 
>> > I'm trying to debug some problems that ModeShape is having in clustered situations when using 5.2.0.CR1. I don't have a standalone test case, but hopefully I can explain what I'm doing.
>> >
>> > I'm working with a replicated cache and two processes. The cache configuration (see attached) uses a cache store (with fetchPersistentState=true) and eviction (though the value of 'maxEntries' is high enough that neither process hits it).
>> >
>> > The first process starts up fine and both ModeShape and Infinispan work fine. After some period of time (~20 seconds), I start up the second process. It joins the cluster, and receives the initial state transfer from the first process. I can see from the logs that an entry with a particular key has been transferred and is complete. The second process (as part of the ModeShape initialization code) attempts to look up the entry with this particular key, but it doesn't find it. At this point, ModeShape starts mis-behaving because this particular entry is critical in knowing if ModeShape needs to initialize the repository content (by creating several hundred entries). Upon finding no such node, it attempts to recreate it and a hundred other entries. Some succeed, but others fail because existing entries are found when they weren't expected to be found. I've replicated this problem on two different machines with different operating systems.
>> >
>> > We're using explicit locks for writes, and we're using a cache with SKIP_REMOTE_LOOKUP and DELTA_WRITE flags when writing, but no particular flags when reading. (See below for why we're using these flags.)
>> >
>> > My understanding is that, once the initial state transfer completes, the second process' cache store should contain all of the transferred entries, and any attempt to look up an entry by key will obviously check local memory and, if not found, will consult the cache store.
>> >
>> > I've attached the log file for this second process. Here are some of the key points in the file:
>> >
>> > 1) Starting with line 39, the log shows that the cache is started, joins the existing cluster, and waits for the initial state transfer. This is follows by lots of lines showing the details of the state transfer.
>> >
>> > 2) On line 159, one of the state transfer DEBUG lines shows a PutKeyValueCommand with the entry of interest, with key "cb80206317f1e7jcr:system" and who's value looks as expected:
>> >
>> > OOB-1,Machine1-27258 2013-01-11 11:31:26,819 TRACE statetransfer.StateTransferInterceptor - handleTopologyAffectedCommand for command PutKeyValueCommand{key=cb80206317f1e7jcr:system, value=SchematicEntryLiteral{ "metadata" : { "id" : "cb80206317f1e7jcr:system" , "contentType" : "application/json" } , "content" : { "key" : "cb80206317f1e7jcr:system" , "parent" : [ "cb80206317f1e7/" , "cb80206cd556c0/" ] , "properties" : { "http://www.jcp.org/jcr/1.0" : { "primaryType" : { "$name" : "mode:system" } } } , "children" : [ { "key" : "cb80206317f1e7jcr:nodeTypes" , "name" : "jcr:nodeTypes" } , { "key" : "cb80206317f1e7jcr:versionStorage" , "name" : "jcr:versionStorage" } , { "key" : "cb80206317f1e7mode:namespaces" , "name" : "mode:namespaces" } , { "key" : "cb80206317f1e7mode:locks" , "name" : "mode:locks" } , { "key" : "cb80206317f1e7mode:synchronizedInitialization" , "name" : "mode:repository" } ] , "childrenInfo" : { "count" : 5 } } }, flags=[CACHE_MODE_LOCAL, SKIP_REMOTE_LOOKUP, PUT_FOR_STATE_TRANSFER, SKIP_SHARED_CACHE_STORE, SKIP_OWNERSHIP_CHECK, IGNORE_RETURN_VALUES, SKIP_XSITE_BACKUP], putIfAbsent=false, lifespanMillis=-1, maxIdleTimeMillis=-1, successful=true}
>> >
>> > 3) On line 673, the log shows that state transfer was completed.
>> >
>> > 4) On line 700, ModeShape calls "cache.get(…)" with the "cb80206317f1e7/" key, and this entry is successfully found:
>> >
>> > com.pb.spring.Main.main() 2013-01-11 11:31:27,667 TRACE statetransfer.StateTransferInterceptor - handleTopologyAffectedCommand for command GetKeyValueCommand {key=cb80206317f1e7/, flags=null}
>> >
>> > 5) On line 704, ModeShape calls "cache.get(…)" with the "cb80206317f1e7jcr:system" key, but this entry is not found:
>> >
>> > com.pb.spring.Main.main() 2013-01-11 11:31:27,687 TRACE statetransfer.StateTransferInterceptor - handleTopologyAffectedCommand for command GetKeyValueCommand {key=cb80206317f1e7jcr:system, flags=null}
>> >
>> > I don't understand why this happens. I understand why the cache doesn't find it in memory, but why doesn't it consult the cache store? Am I missing a specific flag?
>> >
>> > Here's a bit of background. Our SchematicEntryLiteral values are DeltaAware, and we've patterned the code after AtomicHashMap to get the MVCC-style behavior, but our SchematicEntryLiteral values contain JSON-like documents. All of our code can be seen at [1]. Notice our SchematicEntryProxy, and the two Delta implementations. We're using explicit locks for writes, and we're using a cache with SKIP_REMOTE_LOOKUP and DELTA_WRITE flags when writing, but no particular flags when reading.
>> >
>> > BTW, ModeShape creates two cache containers. One of them (created from the "spectrum-workspace-cache.xml" configuration file) is used only for local in-memory caches that use eviction and no persistence; this cache is not really of concern.
>> >
>> > Thanks in advance!
>> >
>> > Randall Hauch
>> >
>> > [1] https://github.com/rhauch/modeshape/tree/1e0db548891a8355651654d0880553b2635b358f/modeshape-schematic/src/main/java/org/infinispan/schematic/internal
>> >
>> > <main2_1357921501.log><spectrum-repository-infinispan.xml>_______________________________________________
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>> > infinispan-dev at lists.jboss.org
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>> 
>> 
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