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0 pointsmodoc12y ago0 comments

Or use sticky sessions and keep the session state server side... Much faster than rebuilding session state for every request (whether from a cookie or from a DB), especially the more complex your app and session state become.

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4 comments · 2 top-level

rubinelli12y ago· 1 in thread

In my experience, sticky sessions open a whole new can of worms. With proxies and VLAN, it's very easy to have an extremely unbalanced load if you use naive IP-based balancing. If one of the servers becomes a "hot spot", adding more servers won't immediately remove the load from that. And when a server dies, the sessions in that server are lost. These problems can be mitigated with an in-memory distributed database overlaid on top of your cluster, but that opens its own can of worms...

modocOP12y ago

Apache and nginx both have an array of good LB algos. I've never seen IP-based LB or hot-spots really. Most app servers support session replication/backup to other node(s). This is really standard stuff in JBoss for instance (my world). Problems that have been solved for years and used at massive scale.

irahul12y ago· 1 in thread

I am assuming by "keep the session server side", you mean keep it in the RAM. If you want to keep the session in the ram, store it in memcache or redis.

Also, the more complex an app becomes, it's generally desirable to have less state, not more(as in sticky sessions).

modocOP12y ago

I'm not sure I agree with either of your points. Sticky sessions with in app/JVM/whatever RAM session objects is much faster than pulling from memcache/redis and parsing/deserializing/instantiating the session state for each request.

Not at all sure what you mean by your second point. Sure generally simplifying things is desirable, but by complex app, I mean an app that has requirements that are complex, and many of those apps require additional session state. For instance keeping track of all categories and products browsed to target recommended products. Keep track of users' site browsing preference, search results, multi-tab interaction, etc...

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