Oct 15, 2009

Interpreting the ActiveMQ 5.3.0 SpecJMS2007® Result

Hot on the heels of the latest Apache ActiveMQ release, official SpecJMS2007® Results appear. ActiveMQ does 156 vertical and 60 horizontal. But what does that mean?

Some Background
SpecJMS2007® is a representative, long-running, comparative test. Let me take each of these in turn.

By representative, I mean that it contains a mix of business interactions that utilises point to point (or queue semantics) and publish/subscribe (topic) semantics. The message sizes vary within limits using random generators and there is a mix of non-persistent and persistent messages. All persistent messages are delivered and consumed within transactions. In reality, the interactions are based around a supermarket supply chain application which provides a rich tapestry for realistic actor interplay. Supermarkets querying suppliers, suppliers interacting with distribution centers and throughout, management in headquarters, keeping track of all dealings.

By long running, I mean that the scenario lasts a minimum of 30 minutes, excluding a warm-up period. The verification phase is based on periodic throughput and response time sampling during that period. In this way, the test verifies the sustainable load characteristics of a JMS Broker.

By comparative, I mean that the test artifacts and environment are completely specified such that results are totally reproducible. For example, if the broker implementation is swapped out from the ActiveMQ submission bundle, a comparable result for the same platform can be obtained. The platform (or OS and hardware configuration) must be maintained to produce comparable results. This focuses the comparison on the implementation of the broker, which is the intention.

Explain the Numbers

The numbers are seed values. They provide the base value or multiplier on which subsequent decisions like the number of destinations, quantity of messages etc. are determined for a given test run. An increase in the seed value has a cascade effect on the overall load that is placed on the system. If the seed value is too high, the overall load will result in a failed test. Either because of unacceptable throughput variance or because of response times exceeding predetermined ranges. To pass the test for a given seed value, all response time and throughput expectations must be met.

The vertical and horizontal qualifiers refer to the SpecJMS2007® workload topologies. The topologies are not directly comparable because the seed multipliers have different effects in both topologies.

As the seed value increases, the vertical scenario aims to increase the number of messages that are processed for a given number of destinations. So in the supermarket supply chain parlance, this means increasing the quantity and variety of stock that is maintained and the frequency of replenishment of said stock. The number of supermarkets and suppliers etc. remains constant as the base seed value increases. In this way, the ability of the broker to deal with increased load on existing destinations is explored. Another way of looking at this is that the depth of the destinations rather than the number of destinations is increased.

As the seed value increases, the horizontal scenario aims to increase the number of destinations while using a fixed load of messages. This corresponds to adding more supermarkets, suppliers and distribution centers. The quantities of stock and the frequency of replenishment is constant. In this way, the ability of the broker to deal concurrently with large numbers of destinations is explored.

In short, the numbers are meaningless in isolation as they are the units of SpecJMS2007® performance measurement and these units have no real-world corollary. Where they are useful is when used in comparison with another run of the SpecJMS2007® test using a different JMS implementation or with some broker configuration tweak.

For example, there are two platform variants of the results, one with Hyper Threading(HT) enabled and the other with HT disabled. The effect is significant indeed, with the vertical successful seed value going from 138 to 156 and horizontal from 52 to 60. So turn HT on!

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