L2 Cache performance is very very bad when writing other kinds of objects in the same transaction ------------------------------------------------------------------------------------------------- Key: HHH-2175 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2175 Project: Hibernate3 Type: Improvement Components: core Versions: 3.2.0.ga Environment: Hibernate Entity Manager 3.2.0 + Annotations + Core Reporter: Sami Dalouche Hibernate L2 Cache performance is very slow when writing objects in the same transaction. For instance. Let's say we have 2 completly unrelated classes A and B let's say A never changes, and we write tons of instances of B to the database. Both A and B are managed by the cache, but into differet cache regions (with different Ehcache configurations). So, let's consider a simple example like : loop 1: for(int i = 0 ; i < 10000 ; i++){ new A(); } and loop2: for(int i = 0 ; i < 10000 ; i++){ aDao.findAByKey("key"); } Since the L2 cache + Query cache is activatedon a + findAByKey, loop2's performance is comparable to loop's 1 one. It's pretty much the same, so everything is fine, so far. Let's call X the time taken by loop1 or loop2, that we consider equal. Now, let's consider loop3 and loop4: loop 3: for(int i = 0 ; i < 10000 ; i++){ new A(); bDao.save(new B()); } and loop4: for(int i = 0 ; i < 10000 ; i++){ aDao.findAByKey("key"); bDao.save(new B()); } So, now, let's consider that saving bDao.save(new B()) takes Y seconds for 10,000 iterations. You would expect loop3 and loop4 to have the same performance, roughly , X + Y, right ? Well, actually, loop3 takes X + Y. But loop4 takes around 20 * (X + Y) !!!!!!! (on my machine, so it can be slighly different). But you see the point : there is a HUGE difference of performance. I am sure there are design reasons for this, that's why I set this bug as an enhancement.. So, 2 things : * either it is possible to solve this issue, and it would be nice to correct it * either it is not possible to solve this issue, and it would be nice to add a section in the reference manual, explaining why hibernate behaves that way. Regards, Sami Dalouche -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://opensource.atlassian.com/projects/hibernate/secure/Administrators.... - For more information on JIRA, see: http://www.atlassian.com/software/jira