before you ask, of course, we are looking into whether this is something on our end. We only made very few changes, but we should be able to isolate this. I'll report on that once I know for sure. My question was more whether anyone knew of any changes in tx that could affect concurrent performance negatively since May 15
thanks Simon From: Simon Helsen/Toronto/IBM@IBMCA To: [email protected] Date: 06/13/2012 10:09 AM Subject: concurrency and slower results hi everyone, Andy especially, it looks like some of the changes to TDB since May 15 have negatively affected the concurrent behavior of Tx. To clarify, we are doing some serious internal performance testing on a product which is based on Jena/TDB. We initially did these runs to compare Tx (2.7.1 snapshot of May 15) with our old TDB implementation (which used a conservative locking model). The results were good, especially with long-running/expensive index update operations. Now, I had asked the performance team to rerun their tests with a new build of the product based on the release candidate (of last weekend) and they are reporting a concerning degradation. Compared to the May 15 TDB, they are reporting 12-15% decrease in query performance when doing a "light update load" and about 40% query and 40% update performance degradation when doing a "heave update load". That is quite a serious regression. The question is what changed since May 15 that could have such a bad effect on performance. The tests included only 25 concurrent users on about 15 million triples. Yet, I wonder if some of the recent lock changes (see JENA-252) are responsible thanks Simon
