Share » Learn » eZ Publish » eZ Publish Knowledge Series: «Stale...

eZ Publish Knowledge Series: «Stale Cache» or «How caches in eZ Publish 4.1 are handled in a smarter way»

Monday 30 March 2009 2:19:00 am

Currently 5 out of 5 Stars.
1
2
3
4
5

Results

We ran series of benchmarks to evaluate the influence of the Stale Cache feature on a website's overall performance and user-experience. One of them consisted in using a JMeter scenario to hammer a specific page, simulating 20 concurrent end-users viewing a fully-cached content node, during one minute. We stressed two very identical instances of eZ Publish, but for the Stale Cache improvement. We wanted to measure the impact of a view cache re-generation under high load and high concurrency. During this minute, the content object's view cache was cleared 8 times. Here is the resulting graph ( volume of requests/sec on the vertical axis ).

The obvious trend on this graph it that upon every cache clearing, with no Stale Cache, eZ Publish's reactivity shrinks down to 40 requests/sec, while being slightly over 60 requests/sec in average otherwise. This is due to the now defunct sub-optimal queue handling in cache management, which frequently resulted in DB deadlocks or other harmful race conditions. As opposed, you can notice the throughput on the Stale-Cache-enabled eZ Publish instance has no correlation with the cache clearings, is rather constant compared to the non Stale Cache version, and rarely drowns under 60 requests/sec. Throughput is smoothened, greatly enhancing user experience. Plus, although not appearing on this graph, system resources are preserved !

Conclusion

The Stale Cache feature is part of the many low-level improvements brought by eZ Publish 4.1, which do not pop up at first glance, but greatly enhance User experience and dramatically reduce the pressure on the architecture. We do recommend you to enable this feature ( unless your servers run Windows with a PHP version <= 5.3 ) in order for your eZ Publish based application to benefit from this instant booster.
We are looking forward to hearing your feedback on this ( and your benchmark results ) !

Thanks for reading !