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Posted to issues@zookeeper.apache.org by "Whitney O'Meara (Jira)" <ji...@apache.org> on 2022/04/07 18:16:00 UTC
[jira] [Commented] (ZOOKEEPER-1622) session ids will be negative in the year 2022
[ https://issues.apache.org/jira/browse/ZOOKEEPER-1622?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17519076#comment-17519076 ]
Whitney O'Meara commented on ZOOKEEPER-1622:
--------------------------------------------
Can confirm... It is 2022, and session ids are negative...
> 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 C. Newton
> Assignee: Eric C. 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.
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