[jira] [Commented] (ZOOKEEPER-1751) ClientCnxn#run could miss the second ping or connection get dropped before a ping

["Mahadev konar (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-1751?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13770310#comment-13770310 ] 

Mahadev konar commented on ZOOKEEPER-1751:
------------------------------------------

+1 for the patch. This is good to have since it can cause some race conditions during the  client pings.
                
> ClientCnxn#run could miss the second ping or connection get dropped before a ping
> ---------------------------------------------------------------------------------
>
>                 Key: ZOOKEEPER-1751
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1751
>             Project: ZooKeeper
>          Issue Type: Bug
>    Affects Versions: 3.4.5
>            Reporter: Jeffrey Zhong
>            Assignee: Jeffrey Zhong
>             Fix For: 3.4.6
>
>         Attachments: zookeeper-1751.patch
>
>
> We could throw SessionTimeoutException exception even when timeToNextPing may also be negative depending on the time when the following line is executed by the thread because we check time out before sending a ping.
> {code}
>   to = readTimeout - clientCnxnSocket.getIdleRecv();
> {code}
> In addition, we only ping twice no matter how long the session time out value is. For example, we set session time out = 60mins then we only try ping twice in 40mins window. Therefore, the connection could be dropped by OS after idle time out.
> The issue is causing randomly "connection loss" or "session expired" issues in client side which is bad for applications like HBase.

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