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https://issues.apache.org/jira/browse/ZOOKEEPER-1676?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13785393#comment-13785393
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Patrick Hunt commented on ZOOKEEPER-1676:
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[~yunong] this sounds like an important one to fix, can you submit a patch per
Michi's comment?
> C client zookeeper_interest returning ZOK on Connection Loss
> ------------------------------------------------------------
>
> Key: ZOOKEEPER-1676
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1676
> Project: ZooKeeper
> Issue Type: Bug
> Components: c client
> Affects Versions: 3.4.3
> Environment: All
> Reporter: Yunong Xiao
> Assignee: Yunong Xiao
> Priority: Critical
>
> I have a fairly simple single-threaded C client set up -- single-threaded
> because we are embedding zk in the node.js/libuv runtime -- which consists of
> the following algorithm:
> zookeeper_interest(); select();
> // perform zookeeper api calls
> zookeeper_process();
> I've noticed that zookeeper_interest in the C client never returns error if it
> is unable to connect to the zk server.
> From the spec of the zookeeper_interest API, I see that zookeeper_interest is
> supposed to return ZCONNECTIONLOSS when disconnected from the client. However,
> digging into the code, I see that the client is making a non-blocking connect
> call
> https://github.com/apache/zookeeper/blob/trunk/src/c/src/zookeeper.c#L1596-1613
> , and returning ZOK
> https://github.com/apache/zookeeper/blob/trunk/src/c/src/zookeeper.c#L1684
> If we assume that the server is not up, this will mean that the subsequent
> select() call would return 0, since the fd is not ready, and future calls to
> zookeeper_interest will always return 0 and not the expected ZCONNECTIONLOSS.
> Thus an upstream client will never be aware that the connection is lost.
> I don't think this is the expected behavior. I have temporarily patched the zk
> C client such that zookeeper_interest will return ZCONNECTIONLOSS if it's
> still
> unable to connect after session_timeout has been exceeded.
> I have included a patch for the client which fixes this for release 3.4.3
> 6b35e96 in this branch:
> https://github.com/yunong/zookeeper/tree/release-3.4.3-patched Here's the
> patch https://gist.github.com/yunong/efe869a0345867d54adf
> For more information, please see this email thread.
> http://mail-archives.apache.org/mod_mbox/zookeeper-dev/201211.mbox/%[email protected]%3E
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