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https://issues.apache.org/jira/browse/ZOOKEEPER-1739?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13734659#comment-13734659
]
Flavio Junqueira commented on ZOOKEEPER-1739:
---------------------------------------------
I'm a bit behind with my reviews, but this change seems trivial. Could you
propose a patch, [~qiaoqingjie]?
> thread safe bug in FastLeaderElection: instance of WorkerSender is not safe
> published, WorkerSender thread may see that WorkerSender.manager is the
> default value null
> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: ZOOKEEPER-1739
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1739
> Project: ZooKeeper
> Issue Type: Bug
> Components: leaderElection
> Affects Versions: 3.4.5
> Reporter: qingjie qiao
> Priority: Minor
>
> I am reading the trunk source code recently and find a thread-safe problem,
> but i'm not quite sure.
> in FastLeaderElection:
> {code}
> class WorkerSender implements Runnable {
> volatile boolean stop;
> QuorumCnxManager manager;
> WorkerSender(QuorumCnxManager manager){
> this.stop = false;
> this.manager = manager;
> }
> public void run() {
> ...
> }
> }
> ...
> Messenger(QuorumCnxManager manager) {
> this.ws = new WorkerSender(manager);
> Thread t = new Thread(this.ws,
> "WorkerSender[myid=" + self.getId() + "]");
> t.setDaemon(true);
> t.start();
> this.wr = new WorkerReceiver(manager);
> t = new Thread(this.wr,
> "WorkerReceiver[myid=" + self.getId() + "]");
> t.setDaemon(true);
> t.start();
> }
> ...
> {code}
> The instance of WorkerSender is constructed in main thread, and its field
> manager is assigned , and it is used in another thread. The later thread may
> see that WorkerSender.manager is the default value null. The solution may be:
> (1) change
> {code}
> WorkerSender(QuorumCnxManager manager){
> this.stop = false;
> this.manager = manager;
> }
> {code}
> to
> {code}
> WorkerSender(QuorumCnxManager manager){
> this.manager = manager;
> this.stop = false;
> }
> {code}
> or(2)
> change
> {code}
> QuorumCnxManager manager;
> {code}
> to
> {code}
> final QuorumCnxManager manager;
> {code}
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