[jira] [Commented] (CALCITE-4489) Avatica JdbcMeta statement IDs Concurrency problem

["Vladimir Sitnikov (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-4489?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17279841#comment-17279841 ] 

Vladimir Sitnikov commented on CALCITE-4489:
--------------------------------------------

{quote} We believe that  the cause of the problem is unsynchronized increment of connection.statementCount{quote}

The counter looks like a per-connection counter, so it should not be a problem provided you do not share connections between the concurrently executing threads.


AFAIK Connection is not thread-safe.

> Avatica JdbcMeta statement IDs Concurrency problem
> --------------------------------------------------
>
>                 Key: CALCITE-4489
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4489
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 1.26.0
>            Reporter: Vlad Skarzhevskyy
>            Priority: Major
>         Attachments: stak-trace.txt
>
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
>   We encountered the JdbcMeta statement IDs concurrency problems that lead to errors pulling the data from avatica JDBC remote http server under heavy load.
>   The error stack trace for the error is  attached.
>   
>   Our setup:   Avatica JDBC remote  http server handled by Calcite on the server side.
>   For the record we had not been able to reproduce the same problems with Avatica, only remote proxy connected directly to DB.
>  
>   We believe that  the cause of the problem is unsynchronized increment of connection.statementCount
>   see  MetaImpl.createStatement
> [https://github.com/apache/calcite-avatica/blob/master/core/src/main/java/org/apache/calcite/avatica/MetaImpl.java#L213]
> {code:java}
> public StatementHandle createStatement(ConnectionHandle ch) {
>      return new StatementHandle(ch.id, connection.statementCount++, null);
> }{code}
>  Suggested  fix is to use  AtomicInteger  for statementCount.
>  Our stress tests show that the problem is resolved by the fix..
>  
>  



--
This message was sent by Atlassian Jira
(v8.3.4#803005)