[jira] [Commented] (TINKERPOP-2044) Cannot reconnect to Azure cosmos host that becomes available again

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TINKERPOP-2044?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16635140#comment-16635140 ] 

ASF GitHub Bot commented on TINKERPOP-2044:
-------------------------------------------

Github user robertdale commented on a diff in the pull request:

    https://github.com/apache/tinkerpop/pull/943#discussion_r221859065
  
    --- Diff: gremlin-driver/src/main/java/org/apache/tinkerpop/gremlin/driver/Settings.java ---
    @@ -243,6 +243,8 @@ public static Settings from(final Configuration conf) {
                 if (connectionPoolConf.containsKey("keepAliveInterval"))
                     cpSettings.keepAliveInterval = connectionPoolConf.getLong("keepAliveInterval");
     
    +            if (connectionPoolConf.containsKey("validationRequest"))
    +                cpSettings.validationRequest = connectionPoolConf.getList("validationRequest").stream().map(Object::toString).collect(Collectors.joining(","));
    --- End diff --
    
    Why is this `getList()` instead of `getString()`?


> Cannot reconnect to Azure cosmos host that becomes available again
> ------------------------------------------------------------------
>
>                 Key: TINKERPOP-2044
>                 URL: https://issues.apache.org/jira/browse/TINKERPOP-2044
>             Project: TinkerPop
>          Issue Type: Bug
>          Components: driver
>    Affects Versions: 3.3.3
>            Reporter: Dantis P S
>            Assignee: stephen mallette
>            Priority: Major
>
> If a Azure Cosmos Gremlin host goes down and if it becomes available again, the tinkerpop3 java driver cannot reconnect to it. 
> Sample code is available at [https://github.com/cancure/tinkerpopcosmos]
>  
> These are the steps to reproduce - 
> 1) Start the application after providing proper connection details in remote.yaml file.
> 2) Call the end point POST [http://localhost:8080/query.] Pass a valid gremlin query as HTTP body E.g. g.V(1).id()
> 3) Disconnect computer from internet. 
> 4) Do step 2.
> 5) Reconnect computer to the internet.
> 6) Do step 2. 
> Any query executed from this point onwards gets the error - "java.lang.RuntimeException: java.util.concurrent.TimeoutException: Timed out while waiting for an available host - check the client configuration and connectivity to the server if this message persists".
>  
> The issue seems to be coming from org.apache.tinkerpop.gremlin.driver.ConnectionPool.java. In line #403, the gremlin query used for ping message is '' (Empty string in single quotes). 
> final RequestMessage ping = RequestMessage.build(Tokens.OPS_EVAL).add(Tokens.ARGS_GREMLIN, "''").create();
>  
> Cosmos server returns an error saying that the gremlin query's grammar is incorrect. Because of this error the rest of the lines of the method does not get executed.
>  
> Fix will be to use a gremlin query which is valid for all supported graph DBs.
>  



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