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Posted to dev@lucene.apache.org by "Javier Mendez (JIRA)" <ji...@apache.org> on 2013/10/21 19:04:43 UTC

[jira] [Created] (SOLR-5373) Can't become leader due infinite recovery loop

Javier Mendez created SOLR-5373:
-----------------------------------

             Summary: Can't become leader due infinite recovery loop
                 Key: SOLR-5373
                 URL: https://issues.apache.org/jira/browse/SOLR-5373
             Project: Solr
          Issue Type: Bug
    Affects Versions: 4.2
         Environment: SolrCloud, 2 nodes, Fedora
            Reporter: Javier Mendez
            Priority: Minor


We found an issue while performing stability tests on SolrCloud. Under certain circumstances, a node will get in an endless loop trying to recover. I've seen this happen in a two node setup, by following these steps:

1) Node A started
2) Node B started
3) Node B stopped
4) Node B started, and immediately Node A stopped (normal graceful shutdown). 

At this point node B will throw connection refused messages while trying to sync to node A. For some reason (not always) this leads to a corrupt state where node B enters an infinite loop trying to recover from node A (it still thinks the cluster has two nodes). I think the leader election process started just fine, but since recovery is running async, at some point node B published it state as recovery failed, hence causing leader election to fail.

Zookeeper /live_nodes has only one file.

This shows on the logs:
    0:57:18,960 INFO INFO  [ShardLeaderElectionContext] (main-EventThread) Running the leader process.
    10:57:19,068 INFO INFO  [ShardLeaderElectionContext] (main-EventThread) Checking if I should try and be the leader.
    10:57:19,068 INFO INFO  [ShardLeaderElectionContext] (main-EventThread) My last published State was recovery_failed, I won't be the leader.
    10:57:19,068 INFO INFO  [ShardLeaderElectionContext] (main-EventThread) There may be a better leader candidate than us - going back into recovery
    10:57:19,118 INFO INFO  [DefaultSolrCoreState] (main-EventThread) Running recovery - first canceling any ongoing recovery
    10:57:19,118 WARN WARN  [RecoveryStrategy] (main-EventThread) Stopping recovery for zkNodeName=10.50.100.30:8998_solr_myCollectioncore=myCollection
    10:57:19,869 ERROR ERROR [RecoveryStrategy] (RecoveryThread) Error while trying to recover. core=myCollection:org.apache.solr.common.SolrException: No registered leader was found, collection:myCollection slice:shard1
            at org.apache.solr.common.cloud.ZkStateReader.getLeaderRetry(ZkStateReader.java:484)
            at org.apache.solr.common.cloud.ZkStateReader.getLeaderRetry(ZkStateReader.java:467)
            at org.apache.solr.cloud.RecoveryStrategy.doRecovery(RecoveryStrategy.java:321)
            at org.apache.solr.cloud.RecoveryStrategy.run(RecoveryStrategy.java:223)
    
    10:57:19,869 ERROR ERROR [RecoveryStrategy] (RecoveryThread) Recovery failed - trying again... (0) core=myCollection
    10:57:19,869 ERROR ERROR [RecoveryStrategy] (RecoveryThread) Recovery failed - interrupted. core=myCollection
    10:57:19,869 ERROR ERROR [RecoveryStrategy] (RecoveryThread) Recovery failed - I give up. core=myCollection
    10:57:19,869 INFO INFO  [ZkController] (RecoveryThread) publishing core=myCollection state=recovery_failed
    10:57:19,869 INFO INFO  [ZkController] (RecoveryThread) numShards not found on descriptor - reading it from system property
    10:57:19,902 WARN WARN  [RecoveryStrategy] (RecoveryThread) Stopping recovery for zkNodeName=10.50.100.30:8998_solr_myCollectioncore=myCollection
    10:57:19,902 INFO INFO  [RecoveryStrategy] (RecoveryThread) Finished recovery process. core=myCollection
    10:57:19,902 INFO INFO  [RecoveryStrategy] (RecoveryThread) Starting recovery process.  core=myCollection recoveringAfterStartup=false

Solr Version: 4.2.1.2013.03.26.08.26.55

Other references to the same issue:

 - https://support.lucidworks.com/entries/23553611-Solr-cluster-not-able-to-recover 
 - http://mail-archives.apache.org/mod_mbox/lucene-solr-user/201306.mbox/%3C1371473296754-4070983.post@n3.nabble.com%3E




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