Re: [infinispan-dev] Using infinispan as quorum-based nosql

Hello. We are using pessimistic transaction mode. In this case everything's already locked by the time of prepare, is not it? As of merge, for quorum mode it's simple - take data from quorum. I think I will try to simply suppress sending data from non-quorum members on merge. Because currently everyone sends it's data and it creates complete mess with unsynchronized data after merge (depending on the timing). Best regards, Vitalii Tymchyshyn ________________________________ From: infinispan-dev-bounces(a)lists.jboss.org [mailto:infinispan-dev-bounces@lists.jboss.org] On Behalf Of Dan Berindei Sent: Wednesday, June 05, 2013 12:04 PM To: infinispan -Dev List Subject: Re: [infinispan-dev] Using infinispan as quorum-based nosql On Mon, Jun 3, 2013 at 4:23 PM, <vitalii.tymchyshyn(a)ubs.com&gt; wrote: Hello. Thanks for your information. I will subscribe and vote for the issues noted. In the meantime I've implemented hacky JgroupsTransport that "downgrades" all (but CacheViewControlCommand and StateTransferControlCommand) SYNCHRONOUS invokeRemotely calls to SYNCHRONOUS_IGNORE_LEAVERS and checks if required number of answers was received with a filter (I've tried to use original invokeRemotely return value but it often returns some strange value, like empty map). It seems to do the trick for me. But I am still not sure if this has any side effects. Indeed, I started working on a solution, but I over-engineered it and then I got side-tracked with other stuff. Sorry about that. The problem with using SYNCHRONOUS_IGNORE_LEAVERS everywhere, as I found out, is that you don't want to ignore the primary owner of a key leaving during a prepare/lock command (or the coordinator, in REPL mode prior to 5.3.0.CR1/ISPN-2772). If that happens, you have to retry on the new primary owner, otherwise you can't know if the prepare command has locked the key or not. A similar problem appears in non-transactional caches with supportsConcurrentUpdates=true: there the primary owner can ignore any of the backup owners leaving, but the originator can't ignore the primary owner leaving. For now I can see merge problem in my test: different values are picked during merge. I am going to dig a little deeper and follow up. But it's already a little strange for me, since the test algorithm is: 1)Assign "old" value to full cluster (it's REPL_SYNC mode) 2)Block coordinator 3)Writer "new" value to one of two remaining nodes. It's syncrhonized to second remaining node 4)Unblock coordinator 5)Wait (I could not find a good way to wait for state transfer but wait in this case). 6)Check the value on coordinator And in my test I am randomly getting "old" or "new" in assert. I am now going to check why. May be I will need to "reinitialize" smaller cluster part to ensure data is taken from the quorum part of the cluster. We don't handle merges properly. See https://issues.jboss.org/browse/ISPN-263 and the discussion at http://markmail.org/message/meyczotzobuva7js What happens right now is that after a merge, all the caches are assumed to have up-to-date data, so there is no state transfer. We had several ideas floating around on how we could force the smaller partition to receive data from the quorum partition, but I think with the public API your best option is to stop all the caches in the smaller partition after the split and start them back up after the merge. Cheers Dan Best regards, Vitalii Tymchyshyn -----Original Message----- From: infinispan-dev-bounces(a)lists.jboss.org [mailto:infinispan-dev-bounces@lists.jboss.org] On Behalf Of Galder Zamarreno Sent: Monday, June 03, 2013 9:04 AM To: infinispan -Dev List Subject: Re: [infinispan-dev] Using infinispan as quorum-based nosql On May 30, 2013, at 5:10 PM, vitalii.tymchyshyn(a)ubs.com wrote: We're aware of the problem (https://issues.jboss.org/browse/ISPN-2402). @Dan, has there been any updates on this? This is not in yet: https://issues.jboss.org/browse/ISPN-263 ^ Not sure if that'll work. @Dan? ^ How Infinispan reacts in these situations depends a lot on the type of communications (synchronous or asynchronous) and the transaction configuration. Mircea can provide more details on this. Cheers, -- Galder Zamarreño galder(a)redhat.com twitter.com/galderz Project Lead, Escalante http://escalante.io Engineer, Infinispan http://infinispan.org _______________________________________________ infinispan-dev mailing list infinispan-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/infinispan-dev Please visit our website at http://financialservicesinc.ubs.com/wealth/E-maildisclaimer.html for important disclosures and information about our e-mail policies. 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