Problem:
1.A starts, B starts see view {A,B} , DistributionManagerImpl.start not called yet because
no distributed cache was started
2. a dist cache is started on A. A's consistent hash sees nodes {A,B} now (as
DistributionManagerImpl.start is called)
3. a dist cache is started on B. The JoinTask fetches A's DCH list of nodes, i.e.
{A,B}
4. B creates a hash function which contains {A,B} (as fetched from A) and itself: {A,B,B}
--- aftert this point DCH in B is unreliable, anyway here is how the timeout happens
5. B.put(k,v). B acquires lock on k, then B's DCH indicates that k should be placed on
B (!!!). Tries a remote call on B, but it will timeout as the lock on k is already held by
user thread that waits
In other words, the problem is caused by the fact that the joiner doesn't expect
itself to be part of the hash function of the remote cache, but it is. I think that the
hash function should check for that, and drop duplicates.
UT is ConcurrentStartWithReplTest
On 7 May 2010, at 16:16, Galder Zamarreno wrote:
----- "Mircea Markus" <mircea.markus(a)jboss.com> wrote:
> I've tried the the same operation sequence on the caches but it works
> without timeout. HR server also defines a cache for it's own purposes,
> I'll try to include that cache as well in the setup and check again.
Do you have log for the attempt you did to replicate the issue below with only caches and
not HR servers? I'd like to see them to verify it.
The other cache you mention is a replicated cache, for topology info. I don't think
it has any bearings here.
>
> On 7 May 2010, at 14:20, Manik Surtani wrote:
>
>> So TopologyChangeTest is a pretty complex test involving HotRod
> clients and servers, etc. Can this be reproduced in a simpler setting
> - i.e., 2 p2p Infinispan instances, add a third, etc., without any
> HotRod components?
>>
>> On 6 May 2010, at 17:51, galder(a)redhat.com wrote:
>>
>>> Hi all,
>>>
>>> As indicated on IRC, running
> org.infinispan.client.hotrod.TopologyChangeTest.testTwoMembers() fails
> randomly with replication timeout. It's very easy to replicate. When
> it fails, this is what happens:
>>>
>>> 1. During rehashing, a new hash is installed:
>>> 2010-05-06 17:54:11,960 4932 TRACE
> [org.infinispan.distribution.DistributionManagerImpl]
> (Rehasher-eq-985:) Installing new consistent hash
> DefaultConsistentHash{addresses ={109=eq-35426, 10032=eq-985,
> 10033=eq-985}, hash space =10240}
>>>
>>> 2. Rehash finishes and the previous hash is still installed:
>>> 2010-05-06 17:54:11,978 4950 INFO
> [org.infinispan.distribution.JoinTask] (Rehasher-eq-985:) eq-985
> completed join in 30 milliseconds!
>>>
>>> 3. A put comes in to eq-985 who decides recipients are [eq-985,
> eq-985]. Most likely, the hash falled somewhere between 109 and 10032
> and since owners are 2, it took the next 2:
>>> 2010-05-06 17:54:12,307 5279 TRACE
> [org.infinispan.remoting.rpc.RpcManagerImpl] (HotRodServerWorker-2-1:)
> eq-985 broadcasting call
> PutKeyValueCommand{key=CacheKey{data=ByteArray{size=9,
> hashCode=d28dfa, array=[-84, -19, 0, 5, 116, 0, 2, 107, 48, ..]}},
> value=CacheValue{data=ByteArray{size=9, array=[-84, -19, 0, 5, 116, 0,
> 2, 118, 48, ..]}, version=281483566645249}, putIfAbsent=false,
> lifespanMillis=-1000, maxIdleTimeMillis=-1000} to recipient list
> [eq-985, eq-985]
>>>
>>> Everything afterwards is a mess:
>>>
>>> 4. JGroups removes the local address from the destination. The
> reason Infinispan does not do it it's because the number of recipients
> is 2 and the number of members in the cluster 2, so it thinks it's a
> broadcast:
>>> 2010-05-06 17:54:12,308 5280 TRACE
> [org.infinispan.remoting.transport.jgroups.CommandAwareRpcDispatcher]
> (HotRodServerWorker-2-1:) real_dests=[eq-985]
>>>
>>> 5. JGroups still sends it as a broadcast:
>>> 2010-05-06 17:54:12,308 5280 TRACE [org.jgroups.protocols.TCP]
> (HotRodServerWorker-2-1:) sending msg to null, src=eq-985, headers are
> RequestCorrelator: id=201, type=REQ, id=12, rsp_expected=true, NAKACK:
> [MSG, seqno=5], TCP: [channel_name=Infinispan-Cluster]
>>>
>>> 6. Another node deals with this and replies:
>>> 2010-05-06 17:54:12,310 5282 TRACE
> [org.infinispan.remoting.transport.jgroups.CommandAwareRpcDispatcher]
> (OOB-1,Infinispan-Cluster,eq-35426:) Attempting to execute command:
> SingleRpcCommand{cacheName='___defaultcache',
> command=PutKeyValueCommand{key=CacheKey{data=ByteArray{size=9,
> hashCode=43487e, array=[-84, -19, 0, 5, 116, 0, 2, 107, 48, ..]}},
> value=CacheValue{data=ByteArray{size=9, array=[-84, -19, 0, 5, 116, 0,
> 2, 118, 48, ..]}, version=281483566645249}, putIfAbsent=false,
> lifespanMillis=-1000, maxIdleTimeMillis=-1000}} [sender=eq-985]
>>> ...
>>>
>>> 7. However, no replies yet from eq-985, so u get:
>>> 2010-05-06 17:54:27,310 20282 TRACE
> [org.infinispan.remoting.transport.jgroups.CommandAwareRpcDispatcher]
> (HotRodServerWorker-2-1:) responses: [sender=eq-985, retval=null,
> received=false, suspected=false]
>>>
>>> 2010-05-06 17:54:27,313 20285 TRACE
> [org.infinispan.remoting.rpc.RpcManagerImpl] (HotRodServerWorker-2-1:)
> replication exception:
>>> org.infinispan.util.concurrent.TimeoutException: Replication
> timeout for eq-985
>>>
>>> Now, I don't understand the reason for creating a hash
> 10032=eq-985, 10033=eq-985. Shouldn't keeping 10032=eq-985 be enough?
> Why add 10033=eq-985?
>>>
>>> Assuming there was a valid case for it, a naive approach would be
> to discard a second node that points to the an address already in the
> recipient list. So, 10032=eq-985 would be accepted for the list but
> when encountering 10033=eq-985, this would be skipped.
>>>
>>> Finally, I thought waiting for rehashing to finish would solve the
> issue but as u can see in 2., rehashing finished and the hash is still
> in the same shape. Also, I've attached a log file.
>>>
>>> Cheers,
>>> --
>>> Galder Zamarreño
>>> Sr. Software Engineer
>>> Infinispan, JBoss Cache
>>>
>
<bad2_jgroups-infinispan.log.zip>_______________________________________________
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>>> infinispan-dev(a)lists.jboss.org
>>>
https://lists.jboss.org/mailman/listinfo/infinispan-dev
>>
>> --
>> Manik Surtani
>> manik(a)jboss.org
>> Lead, Infinispan
>> Lead, JBoss Cache
>>
http://www.infinispan.org
>>
http://www.jbosscache.org
>>
>>
>>
>>
>>
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