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Date: Wed, 27 Jul 2011 13:58:02 -0400
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Subject: Re: Testing SessionExipred based on FAQ
From: Will Johnson <willjohnsonsearch@gmail.com>
To: user@zookeeper.apache.org
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I was just about to ask about the JMX route since it seems to work but i do
observe the 1->4 behavior you mentioned.  I ended up doing my best code wise
and then did some basic testing with iptables but it's not what i would
consider robust testing and far from automated.  Anything that can be done
to allow end users to test their client code in real world-ish situation
would be a huge help since handling these error cases seems to be so
critical to a correctly operating zookeeper application.

- will

On Wed, Jul 27, 2011 at 1:20 PM, Patrick Hunt <phunt@apache.org> wrote:

> On second thought there is one other way - JMX allows you to close a
> session, this could be used similarly. See tests using
> src/java/test/org/apache/zookeeper/test/JMXEnv.java
>
> I think there's an issue with each of these mechanisms though. In a
> real situation you typically see:
>
> 1) client connected successfully to server with session A
> 2) client gets disconnected from server
> 3) time passes (ie the session is expired)
> 4) client regains connectivity to server, gets notified that session is
> expired
>
> In these other cases step 2 is skipped - we go from 1 directly to 4
> (client notified session is expired). Seems like we should have some
> way to simulate this that more closely replicates what the code will
> see in a real situation. I suspect this would be hard w/o a mock
> ZooKeeper though. The more I think about it the more I feel we should
> add such, to enable more/better client side unit testing/verification.
>
> Patrick
>
> On Wed, Jul 27, 2011 at 10:11 AM, Patrick Hunt <phunt@apache.org> wrote:
> > At this point I'm not sure you can reliably do so without
> > https://issues.apache.org/jira/browse/ZOOKEEPER-829
> >
> > Anyone?
> >
> > Patrick
> >
> > On Fri, Jul 22, 2011 at 6:17 AM, Will Johnson
> > <willjohnsonsearch@gmail.com> wrote:
> >> So give the ticket I created and ZOOKEEPER-710 how do i go about testing
> >> session timeouts programmatically?
> >>
> >> On Fri, Jul 22, 2011 at 8:57 AM, Will Johnson
> >> <willjohnsonsearch@gmail.com>wrote:
> >>
> >>> Created: https://issues.apache.org/jira/browse/ZOOKEEPER-1132
> >>>
> >>>
> >>> On Thu, Jul 21, 2011 at 6:25 PM, Patrick Hunt <phunt@apache.org>
> wrote:
> >>>
> >>>> I think the FAQ is out of date, iirc it's probably due to this change
> >>>> https://issues.apache.org/jira/browse/ZOOKEEPER-710
> >>>> specifically
> >>>> "the leader needs to drop the connection when it sees the MOVED error
> >>>> so that the client can reestablish the session properly with another
> >>>> machine"
> >>>> which I believe you are seeing here.
> >>>>
> >>>> Also see this thread, there are other issues:
> >>>> http://markmail.org/message/wqj347dlrsd74qya
> >>>>
> >>>> I would think though that zoo1 should eventually see the session
> >>>> expiration - it will get disconnected but will then re-attempt to
> >>>> connect to the server, at which point it will be notice the session is
> >>>> expired.
> >>>>
> >>>> Would you mind entering a JIRA for this (to update the FAQ). Thanks!
> >>>>
> >>>> Patrick
> >>>>
> >>>> On Thu, Jul 21, 2011 at 1:36 PM, Will Johnson
> >>>> <willjohnsonsearch@gmail.com> wrote:
> >>>> > i'm trying to test SessionExpired based on the FAQ (
> >>>> > http://wiki.apache.org/hadoop/ZooKeeper/FAQ)  can anyone point out
> why
> >>>> i'm
> >>>> > getting ConnectionLoss exceptions instead of
> SessionExpiredExceptions
> >>>> based
> >>>> > on the unit test below:
> >>>> >
> >>>> > @Test
> >>>> >  public void testSimpleConnection() throws Exception {
> >>>> >    String hostPort = "localhost:9999";
> >>>> >    ZooKeeper zoo1 = new ZooKeeper(hostPort, 1000, null);
> >>>> >
> >>>> >    // just make sure we can talk to zookeeper
> >>>> >    Assert.assertNull(zoo1.exists("/foo", false));
> >>>> >    zoo1.create("/foo", null, Ids.OPEN_ACL_UNSAFE,
> CreateMode.EPHEMERAL);
> >>>> >    Assert.assertNotNull(zoo1.exists("/foo", false));
> >>>> >
> >>>> >    // construct another client with the same id
> >>>> >    ZooKeeper zoo2 = new ZooKeeper(hostPort,
> zoo1.getSessionTimeout(),
> >>>> null,
> >>>> > zoo1.getSessionId(), null);
> >>>> >    // closing this session should invalidate the first:
> >>>> > http://wiki.apache.org/hadoop/ZooKeeper/FAQ
> >>>> >    zoo2.close();
> >>>> >
> >>>> >    // sleep just to make sure everything gets evicted
> >>>> >    Thread.sleep(zoo1.getSessionTimeout() * 2);
> >>>> >
> >>>> >    // closing this session should invalidate the first:
> >>>> > http://wiki.apache.org/hadoop/ZooKeeper/FAQ
> >>>> >    // this is where i always get ConnectionLoss instead of
> >>>> SessionExpired
> >>>> >    Assert.assertNull(zoo1.exists("/foo", false));
> >>>> >
> >>>> >  }
> >>>> >
> >>>>
> >>>
> >>>
> >>
> >
>

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