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(a)gmail.com> wrote:
Does it behave like what's described here?
https://docs.jboss.org/author/display/ISPN/Cache+Loaders+and+Stores#Cache...
Thanks,
On Mon, Jan 14, 2013 at 6:53 AM, Randall Hauch <rhauch(a)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(a)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/1e0db548891a8355651654d0880553b2...
>
>
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