Hello Christopher, thanks for the reply,
i will try out DataSource with the JDBCStore and see if that makes any difference. I haven't tried out BackupManager because, according to the documentation, it replicates the session data to only backup node. So I'm not sure if all my clusters in a more-than-2 cluster setup would have the session data. ( https://tomcat.apache.org/tomcat-8.0-doc/cluster-howto.html ) I'm currently using AWS LB and the distribution of load is not fair at times. That being said I have no working issues with a sticky load balancer, just trying to see if I can get the session information replicated and stored faster. How do I get fast cluster replication, I can try and see if that solves my "problem" as well :) --gibu On Fri, Aug 19, 2016 at 1:30 AM, Christopher Schultz < ch...@christopherschultz.net> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA256 > > Gibu, > > On 8/18/16 12:45 PM, Gibu George wrote: > > On Thu, Aug 18, 2016 at 9:17 PM, Christopher Schultz < > > ch...@christopherschultz.net> wrote: > > > > Gibu, > > > > On 8/18/16 10:55 AM, Gibu George wrote: > >>>> I have setup a tomcat cluster that store the session > >>>> information in a mysql dB. I also have a load balancer in > >>>> front of this cluster. > >>>> > >>>> I have noticed a delay, in few seconds, before the session > >>>> information is stored in the dB. Is there any way to reduce > >>>> this delay and get tomcat to store the session information, > >>>> in the dB, instantly? > >>>> > >>>> One of the threads in the tomcat archives talks about > >>>> "synchronous session replication" ( ( > >>>> https://tomcat.apache.org/tomcat-5.5-doc/cluster-howto.html#Cluster > _Co > > > >>>> > nfiguration_for_ReplicationTransmitter_(_synchronous_-_mode) > >>>> > >>>> > > ) ) . Is this still a valid configuration for tomcat8.0 ? > > > > Are you wanting to speed-up replication across the cluster, or the > > writes to the database-backed store? Or both? > > > > > >> Both, speed-up replication across the cluster and reduce the time > >> to write to dB > > Okay, so you do really want cluster replication (for fail-over, > potentially load-balancing). Okay. > > Do you need durable sessions? If you had fast clustered-replication, > would that be good enough? I just want to make sure you really need > what you are asking for, or if you have gotten to this point because > you are trying several ways to share data between nodes. > > >>>> My setup works fine when the load balancer is configured > >>>> with sticky sessions. When sticky sessions are removed, i am > >>>> facing issues in logging into the application thats hosted on > >>>> my tomcat cluster. I believe this is due to the delay in > >>>> storing the session information in dB. Is this right? > > > > Is there a problem using sticky sessions? Sticky sessions are > > pretty much always a good idea since they solve many of these > > problems. Use of sticky sessions does not preclude > > fail-over-without-re-login. > > > > > >> I am facing no major issue at this point with a sticky load > >> balancer, though at times I see most of the requests going to > >> just one machine and the other one almost at idle. Thought of > >> better load distribution across the instances without a sticky > >> load balancer. > > What is acting as your load-balancer? We use httpd + mod_jk and it > does a seemingly fair job of balancing sessions. I have no hard data > for that, though collecting it wouldn't be too hard. > > > Can you post your existing configuration? > > > >> Setup in AWS, so static clustering server.xml : > >> https://gist.github.com/141984/2c2d112afc8115de82c6f659df21cec6 > > For the impatient: > > > <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster" > > channelSendOptions="8"> > > Cluster's channelSendOptions defaults to "8", but I see you have been > trying to force it. I think this setting is for communication in > general between the nodes, not specifically for synchronous > session-replication. I think that's configured in the Manager you are > using. > > It's possible that this comment in the docs: > > " > The default value [for Manager className] is the > org.apache.catalina.ha.session.DeltaManager that is closely coupled > with the SimpleTcpCluster implementation. Other managers like the > org.apache.catalina.ha.session.BackupManager are/could be loosely > coupled and don't rely on the SimpleTcpCluster for its data replication. > " > > Perhaps that means that Cluster's channelSendOptions affects how the > DeltaManager performs its replication. > > > <Manager className="org.apache.catalina.ha.session.DeltaManager" > > expireSessionsOnShutdown="false" > > notifyListenersOnReplication="true"/> > > The BackupManager's mapSendOptions default is "6" which means > "synchronous". I don't see a similar option in the DeltaManager, and > I'm not familiar enough with it to know how it will behave. > > Can you confirm that you are getting HTTP responses before the cluster > has fully-replicated your session changes? > > I'm assuming that the <Channel> and everything are okay, since your > cluster appears to be *working* -- that is, messages do in fact > flow... you just want them to flow slightly differently. > > >> context.xml: > >> https://gist.github.com/141984/7d0b1bbb7acc3131236d981d0f737ded > > > > For the impatient: > > > > <Manager className="org.apache.catalina.session.PersistentManager" > > maxIdleBackup="0"> <Store > > className="org.apache.catalina.session.JDBCStore" > > connectionName="flintstones" connectionPassword="barney" > > connectionURL="jdbc:mysql://7.1.3.9:3306/mysessions" > > driverName="com.mysql.jdbc.Driver" sessionTable="tomcat_sessions" > > sessionAppCol="app_name" sessionDataCol="session_data" > > sessionIdCol="session_id" sessionLastAccessedCol="last_access" > > sessionMaxInactiveCol="max_inactive" > > sessionValidCol="valid_session" /> </Manager> > > > I highly recommend that you use a DataSource with your JDBC store, > though that is only based upon the knowledge that the JDBCRealm has > poor performance because it uses a single JDBC Connection for all of > its work. If you use a DataSourceRealm you get better performance. You > might try that with JDBCStore to see if it makes a difference. > > I see no way to particular way to make JDBCStore synchronous: to > refuse to return a page to the client until after session data has > been written. > > I'm going to rely on Keiichi to help explain the behavior of the > cluster and the associated manager. You could try using BackupManager > with mapSendOptions="6" (the default). > > Hope that helps (a little), > - -chris > -----BEGIN PGP SIGNATURE----- > Comment: GPGTools - http://gpgtools.org > Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ > > iQIcBAEBCAAGBQJXthPCAAoJEBzwKT+lPKRYuXYP/idpY7TUreysfyRRnQ1P+UjG > ea+KGk07uAZrPZZ5wEXuWFb7FtihDyzKWOwSkMIiGSgyft3MLzOBmI8N+u6274MF > 4KshA2PZgN8pzhB9liiAyujVDrJ48YXJSC9B+V4+41wleN+snqO8OpBWrlgejssz > aHGy//PH0oa65/HDb8+oEhMkYQpkcSCj/wI2At8+/2fQAcuUMNypOpcY4VKWzskh > NTOdcsbYwZOw5C+BmTLbL8MNfE9juj/1x1RpzGm7PyeS4jFNZWsG6x9+ZvamhrKZ > /zY9+pBiN11bYQk5P6y1XwOHFEfjfKXAoDwiITUn/x5m8a7X4af9pNFZjlxvFtIj > KdfmY8d4YKCJVsnvaZ6PUC4HZSciMxDGfOUrd3twLbtvHhjgABGj7znymDimpiYX > rMK2/9yA9gCDNt88B0YphcqauHM59G7pHtX7OzIR0TGXaB29h1S22Ah1E7QpOHbr > imK6M5oa4b/X5QBlx/4swyIHTPoWomyf1pASoKapG4zxGRi3BC0OTFzoUHEf79fj > vxiEo4arXq7BXKxphBHVAHPggu3eXQ7idKUACDVSLhyi+0jnv9rM3JsKcXxAM21G > oxUTXFwVq/ZJOADPaHt4YuE4Kwcf4ZMrff8+5WD3YrBO3rb5nkQ6v77Z//mlS3n6 > 8Dardi4KVuEpaOzbBBsw > =phlv > -----END PGP SIGNATURE----- > > --------------------------------------------------------------------- > To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > For additional commands, e-mail: users-h...@tomcat.apache.org > > -- --gibu
