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Posted to dev@tinkerpop.apache.org by "Robert Dale (JIRA)" <ji...@apache.org> on 2018/09/25 01:08:00 UTC
[jira] [Commented] (TINKERPOP-2044) Cannot reconnect to Azure
cosmos host that becomes available again
[ https://issues.apache.org/jira/browse/TINKERPOP-2044?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16626638#comment-16626638 ]
Robert Dale commented on TINKERPOP-2044:
----------------------------------------
My first reaction is to make this a user configurable query like in so many jdbc drivers. I wonder if there's something more appropriate or clever.
> 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
> 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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