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https://issues.apache.org/jira/browse/ZOOKEEPER-2366?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15297305#comment-15297305
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Flavio Junqueira commented on ZOOKEEPER-2366:
---------------------------------------------
Let's see if we can agree on the behavior. Without reconfiguration, if there is
an IOException while starting the cnxn factory, then the server will exit.
You're saying that upon a reconfiguration of the client port, the situation is
different because the server might already have a number of clients connected
to it. But, if we are to close the old port regardless of whether binding to
the new port succeeded, then we'll be losing those clients connections in any
case. I get the point of the server being re-elected and failing every time, we
do want to avoid that scenario, so either we log and proceed or we exit the
server.
> 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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