[ https://issues.apache.org/jira/browse/ZOOKEEPER2789?page=com.atlassian.jira.plugin.system.issuetabpanels:commenttabpanel&focusedCommentId=16022348#comment16022348
]
ASF GitHub Bot commented on ZOOKEEPER2789:

Github user nerdyyatrice commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/262#discussion_r118167130
 Diff: src/contrib/loggraph/src/java/org/apache/zookeeper/graph/JsonGenerator.java

@@ 121,8 +121,8 @@ public JsonGenerator(LogIterator iter) {
} else if ((m = newElectionP.matcher(e.getEntry())).find()) {
Iterator<Integer> iterator = servers.iterator();
long zxid = Long.valueOf(m.group(2));
 int count = (int)zxid;// & 0xFFFFFFFFL;
 int epoch = (int)Long.rotateRight(zxid, 32);// >> 32;
+ long count = zxid & 0xffffffffffL;
 End diff 
How can this be all over the code base instead of a function somewhere in a util file
> Reassign `ZXID` for solving 32bit overflow problem
> 
>
> Key: ZOOKEEPER2789
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER2789
> Project: ZooKeeper
> Issue Type: Bug
> Components: quorum
> Affects Versions: 3.5.3
> Reporter: Benedict Jin
> Fix For: 3.6.0
>
> Original Estimate: 168h
> Remaining Estimate: 168h
>
> If it is `1k/s` ops, then as long as $2^32 / (86400 * 1000) \approx 49.7$ days ZXID will
exhausted. But, if we reassign the `ZXID` into 16bit for `epoch` and 48bit for `counter`,
then the problem will not occur until after $Math.min(2^16 / 365, 2^48 / (86400 * 1000 *
365)) \approx Math.min(179.6, 8925.5) = 179.6$ years.
> However, i thought the ZXID is `long` type, reading and writing the long type (and `double`
type the same) in JVM, is divided into high 32bit and low 32bit part of the operation, and
because the `ZXID` variable is not modified with `volatile` and is not boxed for the corresponding
reference type (`Long` / `Double`), so it belongs to [nonatomic operation] (https://docs.oracle.com/javase/specs/jls/se8
/html/jls17.html#jls17.7). Thus, if the lower 32 bits of the upper 32 bits are divided into
the entire 32 bits of the `long`, there may be a concurrent problem.

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