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https://issues.apache.org/jira/browse/ZOOKEEPER-2366?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15295631#comment-15295631
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Alexander Shraer commented on ZOOKEEPER-2366:
---------------------------------------------
Sure. But keep in mind that many clients could be connected to the follower, so
shutting down may be disruptive.
And more importantly, if this is the leader we're talking about (failed attempt
to change leader's client port), then shutting it down
will bring the whole system down, and it may not recover since it is very
likely to keep trying to become the leader and fail
due to the taken client port. So unless there's some way to raise an alert,
maybe we should just document in the manual
that when changing the client port of a server the admin should always verify
that it worked the port by opening CLI or similar.
BTW, I briefly looked what happens when other ports are changed: for leading
port change, the leader will resign, and for quorum port the leader election is
restarted.
> Reconfiguration of client port causes a socket leak
> ---------------------------------------------------
>
> Key: ZOOKEEPER-2366
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2366
> Project: ZooKeeper
> Issue Type: Bug
> Components: quorum
> Affects Versions: 3.5.0
> Reporter: Timothy Ward
> Assignee: Flavio Junqueira
> Priority: Blocker
> Fix For: 3.5.2
>
> Attachments: ZOOKEEPER-2366.patch, ZOOKEEPER-2366.patch,
> zookeeper.patch
>
>
> The NIOServerCnxnFactory reconfigure method can leak server sockets, and
> hence make ports unusable until the JVM restarts:
> The first line of the method takes a reference to the current
> ServerSocketChannel and then the next line replaces it. The subsequent
> interactions with the server socket can fail (for example if the
> reconfiguration tries to bind to an in-use port). If they fail *before* the
> call to oldSS.close() then oldSS is *never* closed. This holds that port open
> forever, and prevents the user from rolling back to the previous port!
> The code from reconfigure is shown below:
> ServerSocketChannel oldSS = ss;
> try {
> this.ss = ServerSocketChannel.open();
> ss.socket().setReuseAddress(true);
> LOG.info("binding to port " + addr);
> ss.socket().bind(addr);
> ss.configureBlocking(false);
> acceptThread.setReconfiguring();
> oldSS.close();
> acceptThread.wakeupSelector();
> try {
> acceptThread.join();
> } catch (InterruptedException e) {
> LOG.error("Error joining old acceptThread when
> reconfiguring client port " + e.getMessage());
> }
> acceptThread = new AcceptThread(ss, addr, selectorThreads);
> acceptThread.start();
> } catch(IOException e) {
> LOG.error("Error reconfiguring client port to " + addr + " " +
> e.getMessage());
> }
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