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Zookeeper >> mail # user >> ephemeral node not removed after the client session is long gone


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Re: ephemeral node not removed after the client session is long gone
Here is the JIRA.

https://issues.apache.org/jira/browse/ZOOKEEPER-1208
On Tue, Sep 27, 2011 at 5:42 PM, Camille Fournier <[EMAIL PROTECTED]>wrote:

> This:
>
> HashSet<String> es = zks.getZKDatabase()
> .getEphemerals(request.sessionId);
>
> Is outside the synchronized block that deletes the ephemerals:
>
>                 synchronized (zks.outstandingChanges) {
>     for (ChangeRecord c : zks.outstandingChanges) {
>     if (c.stat == null) {                            // Doing a delete
>                            es.remove(c.path);                        }
> else if (c.stat.getEphemeralOwner() == request.sessionId) {
>                 es.add(c.path);                        }
>      }                    for (String path2Delete : es) {
>           addChangeRecord(new ChangeRecord(txnHeader.getZxid(),
>                         path2Delete, null, 0, null));
>   }                }
> On Tue, Sep 27, 2011 at 7:26 PM, Mahadev Konar <[EMAIL PROTECTED]>
> wrote:
> > Camille,
> >  I am a little confused on the explanation/text. Probably might want
> > to update the jira (if kishore opens one) with a little more detail.
> >
> > thanks
> > mahadev
> >
> > On Tue, Sep 27, 2011 at 2:20 PM, Fournier, Camille F.
> > <[EMAIL PROTECTED]> wrote:
> >> So, the node was created by 0x13220b93e610550 at 12:17:56, then that
> session closed at 12:17:57, the node did not delete, and a bunch of other
> sessions later tried to create the node. These sessions got nodeexists
> failures I presume?
> >>
> >>
> >> Forgive the block of text I'm going to write instead of code:
> >>
> >> I'm going to bet that the problem lies in PrepRequestProcessor. If we
> get the ephemerals for the session while an ephemeral is still in
> outstandingChanges and has not been committed, then another thread commits
> that ephemeral and removes it from outstanding changes before synchronizing
> in the outstandingChagnes block, we could never put it in the ephemeral set
> that we are using to reflect ephemerals to delete. I think we need to move
> the synchronized block up before we get the ephemerals from the database.
> But this is a bit of speculation at the moment. Can you create a JIRA
> tracker for me to look at this?
> >>
> >> Thanks,
> >> C
> >>
> >>
> >>
> >> -----Original Message-----
> >> From: kishore g [mailto:[EMAIL PROTECTED]]
> >> Sent: Monday, September 26, 2011 1:07 AM
> >> To: [EMAIL PROTECTED]
> >> Subject: Re: ephemeral node not removed after the client session is long
> gone
> >>
> >> Hi,
> >>
> >> I got the following information from the logs.
> >>
> >> The node that still exists is
> >>
> /kafka-tracking/consumers/UserPerformanceEvent-<host>/owners/UserPerformanceEvent/529-7
> >>
> >> I saw that the ephemeral owner is 86167322861045079 which is session id
> >> 0x13220b93e610550.
> >>
> >> After searching in the transaction log of one of the ZK servers found
> that
> >> session expired
> >>
> >> 9/22/11 12:17:57 PM PDT session 0x13220b93e610550 cxid 0x74 zxid
> 0x601bd36f7
> >> closeSession null
> >>
> >> On digging further into the logs I found that there were multiple
> sessions
> >> created in quick succession and every session tried to create the same
> node.
> >> But i verified that the sessions were closed and opened in order
> >> 9/22/11 12:17:56 PM PDT session 0x13220b93e610550 cxid 0x0 zxid
> 0x601bd36b5
> >> createSession 6000
> >> 9/22/11 12:17:57 PM PDT session 0x13220b93e610550 cxid 0x74 zxid
> 0x601bd36f7
> >> closeSession null
> >> 9/22/11 12:17:58 PM PDT session 0x13220b93e610551 cxid 0x0 zxid
> 0x601bd36f8
> >> createSession 6000
> >> 9/22/11 12:17:59 PM PDT session 0x13220b93e610551 cxid 0x74 zxid
> 0x601bd373a
> >> closeSession null
> >> 9/22/11 12:18:00 PM PDT session 0x13220b93e610552 cxid 0x0 zxid
> 0x601bd373e
> >> createSession 6000
> >> 9/22/11 12:18:01 PM PDT session 0x13220b93e610552 cxid 0x6c zxid
> 0x601bd37a0
> >> closeSession null
> >> 9/22/11 12:18:02 PM PDT session 0x13220b93e610553 cxid 0x0 zxid
> 0x601bd37e9