Thursday, 27 October 2011
I’m very proud to announce yet another beta release in the 5.1 'Brahma' series. This time is the turn of Infinispan 5.1.0.BETA3 which apart from containing many small fixes, it comes with two major improvements:
Fine-grained Atomic Maps
Atomic Maps are special constructs that users can use to bundle data into the value side of a key/value pair. What’s special about them is that when the map changes, only the changes or deltas of that map are transfered, which makes Atomic Maps very efficient from a replication perspective when individual elements are modified.
Up until Infinispan 5.1.0.BETA2, the other interesting characteristic of these Atomic Maps was the fact that Atomic Map locking and isolation happened at the the level of the entire Atomic Map. So, if a single key/value pair in the Atomic Map was modified, the entire map was locked.
Starting with Infinispan 5.1.0.BETA3, thanks to Vladimir Blagojevic, Atomic Maps supporting fine-grained locking are available as well. What this means is that an Atomic Map’s key/value pairs can be modified in parallel thanks to the ability to lock individual map entries as opposed to the entire map.
This will be particularly handy for heavy Atomic Map users such as JBoss Application Server 7 which uses Atomic Maps for maintaining HTTP sessions, and Hibernate OGM which decomposes entities into Atomic Maps.
Hot Rod server topology improvements
When we originally designed Hot Rod protocol version 1.0, we decided that whenever a distributed cache wanted to send information about the topology of the backend servers to the clients, we’d send the hash ids of each of these nodes. At the time, this seemed like a good idea, until virtual nodes were implemented…
With virtual nodes, each physical Hot Rod server can potentially represent tens, hundreds or even thousands of different virtual nodes. If we stuck with the original protocol, that would mean that we’d have to send each virtual node’s hash id back to the client. So, for a cluster of 8 nodes, and 1000 virtual nodes, that’d be at least 80kb of hash ids being transfered back to the client, on top of tons of redundant information about a node’s host and port, which is very inefficient.
So, after having some discussions, we decided to evolve the Hot Rod protocol to version 1.1 in order to address this issue. The end result is that now it’s the responsibility of the Hot Rod client to generate the hash ids of each of the physical nodes. We do that by sticking to a general formula to generate a Hot Rod server’s hash id which both the Hot Rod server and clients can implement.
This improvement has also lead to the significant decrease in memory consumption of the Hot Rod server because it does not need to cache those hash ids anymore.
So, if you are using Infinispan Hot Rod servers and in particular you’are configuring virtual nodes, you definitely should be upgrading your Hot Rod server and client libraries. From a client code perspective, no changes are necessary because starting with 5.1.0.BETA3, Hot Rod clients talk to servers using this latest protocol.
Tags: atomic maps hotrod