http://www.kaigrabfelder.de/en/2009/05/01/concurrency_vs_synchronization.html After getting up this morning I thought it would be good to contribute something back to my favourite ORM tool: iBATIS. I picked up IBATIS-508 and tried to create a unit test before applying the patch. Unfortunately I was not able to create one so I ... en Kai Grabfelder Sat, 06 Mar 2010 11:04:12 GMT Pebble (http://pebble.sourceforge.net) http://backend.userland.com/rss http://www.kaigrabfelder.de/en/2009/05/01/concurrency_vs_synchronization.html#comment1267873452055 Somewhat late, but here are my results: impl. strategy: no synchronization avg calls per thread: 26.076.005 impl. strategy: synchronized block avg calls per thread: 6.120.937 impl. strategy: synchronized block + Collections.synchronizedMap avg calls per thread: 3.165.427 impl. strategy: Collections.synchronizedMap avg calls per thread: 6.860.422 impl. strategy: java5 ConcurrentHashMap avg calls per thread: 22.508.639 3.3GHz Dual Core. It's a nice CPU Benchmark ;) Arthur http://www.kaigrabfelder.de/en/2009/05/01/concurrency_vs_synchronization.html#comments http://www.kaigrabfelder.de/en/2009/05/01/concurrency_vs_synchronization.html#comment1267873452055 Sat, 06 Mar 2010 11:04:12 GMT http://www.kaigrabfelder.de/en/2009/05/01/concurrency_vs_synchronization.html#comment1241454595462 thanks for the comments. I don't think that duplicated ClassInfo classes are a problem. I doub't that anybody is using == on them. @frz: I was not aware that ClassInfo2 could break the HashMap. I thought concurrent access would be fine as long as the key is different between the different threads. Thanks for pointing this out! Kai Grabfelder http://www.kaigrabfelder.de/en/2009/05/01/concurrency_vs_synchronization.html#comments http://www.kaigrabfelder.de/en/2009/05/01/concurrency_vs_synchronization.html#comment1241454595462 Mon, 04 May 2009 16:29:55 GMT http://www.kaigrabfelder.de/en/2009/05/01/concurrency_vs_synchronization.html#comment1241436573287 ClassInfo2 does not work as you could concurrently access the HashMap for different clazz'es which can break it. Frz http://www.kaigrabfelder.de/en/2009/05/01/concurrency_vs_synchronization.html#comments http://www.kaigrabfelder.de/en/2009/05/01/concurrency_vs_synchronization.html#comment1241436573287 Mon, 04 May 2009 11:29:33 GMT