Awesome, this may be just the thing I will need in an application I
have to write soon.
Thanks.
-- Joshua T. Pyle Go has always existed.On 6/22/05, Paul Cowan <pwc2..ahoo.com> wrote: > FYI for users interested in this topic... > > I just tested the 3 options Andrus listed below. I don't see much performance > difference between number 1 and number 2. However, number 3 yields much > higher performance if you use an LRULinkedHashMap, and keep the maximum number > of objects in the map small. The smaller the map, the faster the performance. > I also get better performance calling commitChanges() every 10,000 changes > instead of every 1,000. But don't see much difference between 10,000 and > 100,000. All depends on the application of course. > > Source for my modified test program with the LRUHashMap is available here: > http://www.buzzsurf.com/java/cayenne/PerfTest.java > > -Paul > > > > --- Andrus Adamchik <andru..bjectstyle.org> wrote: > > > In general (also answering Holger's message) - I am all for smarter > > ObjectStore that covers a wider range of use scenarios. I am not ready to > > say which way is better or more generic - weak reference map or an LRU > > map. If you want to discuss this further, let's use cayenne-devel list. > > > > For now there is a number of options: > > > > 1. Replace a DataContext every so often > > 2. Use ObjectStore.startTrackingNewObjects()/unregisterNewObjects() - we > > don't advertise this API to often, but it works pretty well. > > 3. Create an ObjectStore subclass along these lines: > > > > public class MyObjectStore extends ObjectStore { > > public MyObjectStore(DataRowStore cache) { > > super(cache); > > super.objectMap = some weak-reference or LRU map... > > } > > } > > > > > > DataDomain domain = Configuration.getSharedConfiguration().getDomain(); > > ObjectStore os = new MyObjectStore(domain.getSharedSnapshotCache()); > > DataContext context = new DataContext(domain, os); > > > > I haven't tried the last scenario, hope it won't break the faulting. > > > > Andrus > > > > > Yes, when I create a new DataContext every 1000 iterations, performance > > > does > > > not suffer any longer. > > > > > > However, it kinda seems like an inconvienent or kludgy fix. I wonder if > > > something could be done using weak references in the cache to solve this. > > > I > > > really liked using just one DataContext for this particular app. It does > > > a > > > lot of very short lived object creation. > > > > > > > > > > > > > > > > > > > > > --- Andrus Adamchik <andru..bjectstyle.org> wrote: > > > > > >> Paul, > > >> > > >> Cache settings have effect on the shared cache in a multiuser app. For a > > >> single session DataContext (or rather its ObjectStore) has no upper > > >> limit > > >> on the number of cached objects as it is designed to have a shorter life > > >> span. > > >> > > >> So a more realistic performance test would actually discard a > > >> DataContext > > >> and create a new one after a few operations (how many is "few" depends > > >> on > > >> your expected usage patterns). > > >> > > >> FYI: Here is the stack structure (default is level 2): > > >> http://objectstyle.org/cayenne/userguide/design/caching.html > > >> > > >> Andrus > > >> > > >> > > >> > Hi Andrus, > > >> > > > >> > I'm seeing behaviour in my app using Cayenne, where it runs slower and > > >> > slower > > >> > the longer the application runs without a restart. I suspect that it > > >> will > > >> > eventually run out of memory. Upon restart, performance starts out > > >> high > > >> > again. > > >> > > > >> > I wrote a very simple test application to rule out any of my custom > > >> code. > > >> > It > > >> > simply registers a new objects with the DataContext, sets a property, > > >> and > > >> > calls commitChanges. The test app prints out the elapsed time for > > >> every > > >> > 1000 > > >> > iterations. The results are here: > > >> > > > >> > http://www.buzzsurf.com/java/cayenne/results.txt > > >> > > > >> > If you want to run the simple test application yourself, it's here: > > >> > > > >> > http://www.buzzsurf.com/java/cayenne/CayennePerfTest.zip > > >> > > > >> > As you can see, performance degrades linearly over time. It seems > > >> like > > >> > DataContext is caching a pointer to every object created, despite my > > >> cache > > >> > settings?? I've been playing with the "Max Number of Objects" setting > > >> in > > >> > the > > >> > Modeler, but different settings seem to have no effect. > > >> > > > >> > -Paul > > >> > > > >> > > > >> > > > >> > > >> > > > > > > > > > > > >
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