Serious performance lost within IdentityMap... ---------------------------------------------- Key: HHH-1612 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-1612 Project: Hibernate3 Type: Improvement

Components: core Versions: 3.1.3 Reporter: Peter Fassev Priority: Critical Attachments: Hibernate_3.1.3_performance.jpg Please look at the attached profiler snapshot. After I switched from 3.0.5 to 3.1.3 I have mentioned a serious performance decrease when perfecting data, especially on loading non lazy collection (for instance Arrays of String[]). A simple fetch query, which was executed in 6 seconds on hibernate 3.0.5, now it takes 40 seconds on 3.1.3 (without any changes to the application). The fetch of the whole data needs with 3.1.3 about 90 seconds, with 3.0.5 about 49, which is a serious performance lost. The NetBeans Profiler shows a huge increase of the self time of the IdentityMap.entrySet() method. Now it takes 22,3% of the whole start time. Together with it's calling method BatchFetchQueue.getCollectionBatch() it consumes 36 % of the start time, which explains the performance lost pretty good. Looking at the source code I saw that there is already a TO DO regarding the performance of the IdentityMap.entrySet(), so please fix it, if possible. I think the whole implementation of the IdentityMap should be rethinked, because currently only a dirty hack is possible. If you can't use the IdentityHashMap of 1.4 due to compatibility reasons, please take a look at the current release of apache commons-collections (3.1), where you will find an IdentityHashMap. With best regards Peter