On Wed, Sep 14, 2011 at 9:30 PM, Laxman <[email protected]> wrote: > Pat & Camille, Thanks for your response. > >> I don't think you need to touch the tickTime here. See "maxSessionTimeout" >> here: >> http://zookeeper.apache.org/doc/r3.3.3/zookeeperAdmin.html#sc_advancedConf >> iguration >> (hbase has a similar issue, that's why we added this feature initially). > > I've tried this maxSessionTimeout. This satisfies my customer's requirement. > I also agree that, we still need to fix the GC issue. This has been > discussed with our customer and "maxSessionTimeout" is provided to unblock > them temporarily. > >>It does mean that if you >> have clients writing directly to the ZK client (instead of through a >> wrapper you provide), you need to encourage people not to use MAX_INT in >> their default client setup unless they need the long timeout. > > This is clear and in fact we are using the session timeout value of 30 > seconds only for many use cases like Namenode HA. >
That's true (see Camille's response, I missed highlighting this in my response, but it's absolutely the case). > Thanks again for your quick response. NP. Good Luck. Patrick > >> -----Original Message----- >> From: Fournier, Camille F. [mailto:[email protected]] >> Sent: Wednesday, September 14, 2011 11:48 PM >> To: '[email protected]'; '[email protected]' >> Subject: RE: Impacts of increasing ZooKeeper ticktime >> >> Session timeout is negotiated though eh? So if only the clients that need >> the long GC session expiration time set their client session timeout to >> MAX_INT, other clients can keep it at a lower number and not have a >> problem. That's how we have resolved the issue. It does mean that if you >> have clients writing directly to the ZK client (instead of through a >> wrapper you provide), you need to encourage people not to use MAX_INT in >> their default client setup unless they need the long timeout. >> >> C >> >> -----Original Message----- >> From: Patrick Hunt [mailto:[email protected]] >> Sent: Wednesday, September 14, 2011 1:44 PM >> To: [email protected]; [email protected] >> Subject: Re: Impacts of increasing ZooKeeper ticktime >> >> On Wed, Sep 14, 2011 at 3:23 AM, Laxman <[email protected]> wrote: >> > Our customers are recently complaining about zookeeper client session >> > timeouts. >> > >> > When analyzed its found that timeouts are due to heavy GC activity on >> > Clients. >> > >> > So, they wanted to increase the session timeouts to 3 minutes which >> requires >> > the ticktime to be increased to atleast 9 seconds. >> > >> >> I assume you've talked to them about fixing their gc issue at some >> point? Rather than band-aiding it? :-) >> >> I don't think you need to touch the tickTime here. See "maxSessionTimeout" >> here: >> http://zookeeper.apache.org/doc/r3.3.3/zookeeperAdmin.html#sc_advancedConf >> iguration >> (hbase has a similar issue, that's why we added this feature initially). >> >> Really though they should fix the gc issue - setting the session >> timeout higher means that their sessions will be expiring only after a >> much longer time. Any reliance on this - such as for leader election >> fail-over, will now take much more time. In your example it would take >> 3 minutes for the other clients to notice when a client with the >> particular session has become unavailable. Perhaps it doesn't matter >> in your use case, but you are now likely to get complains about ZK not >> being responsive. ;-) >> >> Regards, >> >> Patrick > >
