Hi, I am doing some analysis for the memory usage since we are running into a couple of problems in our project when doing import of large quantities of objects. I’ve created a simple testcase which does the following:
1) Create all objects (2 classes, one class with 5 string attributes, the other is embedded and has no attributes); 2) Call makePersistent() on the objects; 3) Call commit(); The results: - After step 1) takes up 23 mb of memory in the testcase; - After step 2) the memory usage has increased to 191 mb. Actually there are 3 scenarios I used: 1) Creating objects without the embedded class (which has no attributes, just an empty class): 75 mb 2) Creating objects with the embedded class instantiated: 180 mb; 3) Creating objects with the embedded class instantiated and after makePersistent() again instantiated (overwriting the previous value): 191 mb - During step 3) commit() the memory usage peaks at 580mb So, 1) to persist objects which take up 23mb of memory, a total of 580mb so giving a memory overhead of a factor 25 by the openjpa! 2) maintaining the datastructure whether objects are persistent increases the memory with a factor of 4 to 8, depending whether embeddable objects are used; 3) “overwriting” embedded objects within a transaction, the previous embedded object still seems to take up some memory; I haven’t done a thorough analysis on this but some interesting things I noticed from the profiler: 1) One of the hotspots is in storing the RowImpl._sql. If I am not mistaken, this sql is stored (cached) for each object to be inserted. So in large transactions where a lot of similar objects and modifications are involved, this is quite a duplication which leads to unnecessary memory overhead. Of course there is a performance gain of caching it, but may be this should be better balanced with memory usage?; 2) Though I’ve set kodo.Log=none there is a hotspot in LoggingConnectionDecorator? Is this decorator used for something else as well or is this a bug? I removed it in code from DecoratingDatasource and this reduced the total memory usage to 500mb Comments are welcome. Kind regards, Christiaan -- View this message in context: http://www.nabble.com/Memory-overhead-by-openjpa-tp14438029p14438029.html Sent from the OpenJPA Developers mailing list archive at Nabble.com.
