[jira] [Commented] (ZOOKEEPER-1622) session ids will be negative in the year 2022

["Flavio Junqueira (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-1622?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13824801#comment-13824801 ] 

Flavio Junqueira commented on ZOOKEEPER-1622:
---------------------------------------------

[~phunt], is this a +1 for you?

> session ids will be negative in the year 2022
> ---------------------------------------------
>
>                 Key: ZOOKEEPER-1622
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1622
>             Project: ZooKeeper
>          Issue Type: Bug
>    Affects Versions: 3.4.0, 3.5.0
>            Reporter: Eric Newton
>            Assignee: Eric Newton
>            Priority: Trivial
>             Fix For: 3.4.6, 3.5.0
>
>         Attachments: ZOOKEEPER-1622.patch
>
>
> Someone decided to use a large number for their myid file.  This cause session ids to go negative, and our software (Apache Accumulo) did not handle this very well.  While diagnosing the problem, I noticed this in SessionImpl:
> {noformat}
>    public static long initializeNextSession(long id) {
>         long nextSid = 0;
>         nextSid = (System.currentTimeMillis() << 24) >> 8;
>         nextSid =  nextSid | (id <<56);
>         return nextSid;
>     }
> {noformat}
> When the 40th bit in System.currentTimeMillis() is a one, sign extension will fill the upper 8 bytes of nextSid, and id will not make the session id unique.  I recommend changing the right shift to the logical shift:
> {noformat}
>    public static long initializeNextSession(long id) {
>         long nextSid = 0;
>         nextSid = (System.currentTimeMillis() << 24) >>> 8;
>         nextSid =  nextSid | (id <<56);
>         return nextSid;
>     }
> {noformat}
> But, we have until the year 2022 before we have to worry about it.



--
This message was sent by Atlassian JIRA
(v6.1#6144)