On 2/23/09 11:37 PM, "Joey Echeverria" <joe...@gmail.com> wrote:
> Thanks for the link to the documentation. I've been running tests with > a 5 second session timeout and disconnect events appear frequent. The > network they're operating on is generally quite, but the disconnects > to correlate with an increase in activity (e.g. loading data into the > system). > > Does this seem normal to you or does it imply a potential > configuration problem on my network? How many zookeeper quorum servers are you running? What is the config for the zookeeper servers? > > On a related topic, I was reading the 3.1 client source code, > particularly the reconnect source, and noticed that the client sleeps > for up to 1 second before trying to reconnect. This seems excessive > and with a 5 second session timeout leads to more frequent session > expirations. Almost every time it sleeps for more than about 800 ms, a > disconnect is followed by an expiration. Can you point me to the code which you think does this? A client is supposed to disconnect itself from a server if it does not hear a response to its ping's within 1/3 of the session timeout. It should then reconnect to the other servers. Session expiration happening so frequently does indicate a problem. More information on your setup will help. Thanks mahadev > > Is this a bug, or desirable behavior? > > Thanks, > > -Joey > > On Mon, Feb 23, 2009 at 10:37 PM, Patrick Hunt <ph...@apache.org> wrote: >> The latest docs (3.1.0 has some updates to that section) can be found here: >> http://hadoop.apache.org/zookeeper/docs/r3.1.0/zookeeperProgrammers.html#ch_z >> kSessions >> >> Patrick >> >> Mahadev Konar wrote: >>> >>> Hi Joey, >>> here is a link to information on session timeouts. >>> >>> http://hadoop.apache.org/zookeeper/docs/r3.0.1/zookeeperProgrammers.html#ch_ >>> zkSessions >>> The session timeouts depends on how sensitive you want your application >>> to >>> be. A very low session timeout like (1-2 seconds) might lead to your >>> application being very sensitive to events like minor network problems >>> etc., >>> a higher values of say (30 seconds) on the other hand might lead to slow >>> detection of client failures -- example one of the zookeeper client which >>> has ephemeral node goes down, in this case the ephemeral nodes will only >>> go >>> away after session timeout. >>> >>> I have seen some users using 10-15 seconds of session timeout, but you >>> should use as per your application requirements. >>> >>> Hope this helps. >>> mahadev >>> >>> >>> On 2/22/09 3:09 AM, "Joey Echeverria" <joe...@gmail.com> wrote: >>> >>>> Is there a recommended session timeout? Does it change based on the >>>> ensemble size? >>>> >>>> Thanks, >>>> >>>> -Joey >>> >>
