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From Gunnar Wagenknecht <gun...@wagenknecht.org>
Subject Re: Zookeeper as webapp Session Storage
Date Tue, 16 Jul 2013 15:35:46 GMT

On 2013-07-16 12:28:51 +0000, Stephane Gamard said:
> I see a lot of fuzz about jetty-no-sql session storage, but little 
> about ZK as the storage for jetty sessions.

The Jetty NoSql session storage is based on MogoDB.

I thought about using ZooKeeper for Jetty sessions storage as well but 
ZooKeeper has some limitations which didn't make it a first-class 
choice. The most significant one is the 1MB limit. Well, one can argue 
that a 1MB session is probably already too heavy but I've learned that 
once you offer developers the benefit of a session, they'll throw a lot 
stuff init. Especially when a session is used more as a local cache it 
should really be not stored in ZooKeeper but it some other central 
memory store like Memcache or Redis.

Also, remember that session updates would mean writes in ZooKeeper. 
Thus, too frequent session updates would mean a serious effect on the 
overall system scalability because you then depend on the ZooKeeper 
cluster (its master and a majority) to flush stuff to disc.


Gunnar Wagenknecht

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