[jira] [Commented] (SOLR-4044) CloudSolrServer early connect problems

["Alan Woodward (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SOLR-4044?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14339947#comment-14339947 ] 

Alan Woodward commented on SOLR-4044:
-------------------------------------

Moving the conversation over from SOLR-7146...

bq. Seems like clients should normally be read-only w.r.t. ZK.

This isn't the case at the moment - ZkStateReader.createClusterStateWatchersAndUpdate already calls ensureExists() on the aliases and clusterstate.json znodes.  I agree that it sounds like a good idea, though.

Maybe a nicer way forward would be:
* throw a 503 SolrServerException if any of the watcher nodes don't exist in ZkStateReader when cCSWAU is called
* add a sugar waitForCluster(timeout) method to CloudSolrClient that will repeatedly check zk for the relevant nodes

Also, if we want to really ensure that clients never actually change ZK, we could add a ReadOnlyZkClient that subclasses SolrZkClient and throws UOE on makePath() and setData(), and make CloudSolrClient use that.

> CloudSolrServer early connect problems
> --------------------------------------
>
>                 Key: SOLR-4044
>                 URL: https://issues.apache.org/jira/browse/SOLR-4044
>             Project: Solr
>          Issue Type: Bug
>          Components: SolrCloud
>    Affects Versions: 4.0
>            Reporter: Grant Ingersoll
>            Assignee: Mark Miller
>            Priority: Minor
>             Fix For: 4.9, Trunk
>
>         Attachments: SOLR-4044.patch
>
>
> If you call CloudSolrServer.connect() after Zookeeper is up, but before clusterstate, etc. is populated, you will get "No live SolrServer" exceptions (line 322 in LBHttpSolrServer):
> {code}
> throw new SolrServerException("No live SolrServers available to handle this request");{code}
> for all requests made even though all the Solr nodes are coming up just fine.  



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