Hello, is there still no help for me? Is somebody able to explain me, why i get this "java.util.ConcurrentModificationException" on iterating and calling remove() on the LRUMap?
Please René 2009/6/10 Renè Glanzer <rene.glan...@gmail.com>: > Hello Ted, > > thanks for the fast response. I understand that simultaneously puts > and gets do not cause the exception cause they are synchronized in my > class. > And my stated code-fragment is the part which wants to delete the > entries from the underlying LRUMap. And my code is wrapped in the > synchronized block. But i think the LRUMap herselfe also iterates the > entries and this maybe happens at the same time when my iterator is > checking and trying to delete elements. My class is not implementing > the LRUMap but has one LRUMap as a variable. > So your solution to override the removeLRU(Entry) methode would not > help me....unfortunatelly :-( > > For now i really do not know how to solve the problem in an easy way > without refractoring the entire code? > Any other solutions? > Thanks René > > > > 2009/6/9 Ted Dunning <ted.dunn...@gmail.com>: >> I apologize for not reading your thread with great care, but I think that >> your problem is pretty clear. >> >> The issue is not to do with gets and puts overlapping. The issue is that a >> put or remove happened during the life of your iterator. >> >> One way to avoid this is to synchronize the entire method that does the >> deletion of old elements. To speed that up, you might just synchronize the >> scan for elements to delete and collect them into a list. Then you can >> delete them outside the loop. Since your scan is probably pretty fast, this >> may be sufficient. With very high levels of updates and threading, it would >> cause problems. >> >> Another option is to clone the table. I believe that some implementations >> of LRUMap in Lucene do copy-on-write semantics, but I don't think that >> collections has these. Without that, cloning will be as slow or slower than >> your scan so the first option would be better. >> >> I am curious, however, why you didn't make use of the built-in capabilities >> of the LRUMap to help you with this. Notably, you should probably just >> over-ride the removeLRU(Entry) method and set the scanUntilRemovable flag. >> I think that this would take the place of your loop and would be much more >> efficient. >> >> On Tue, Jun 9, 2009 at 9:33 AM, Renè Glanzer <rene.glan...@gmail.com> wrote: >> >>> ... Additionally to the maximum number of the LRUMap i also implemented a >>> thread which periodicly checks the age of the entries and deletes them >>> when they are too old. >>> >>> For this i generated an Iterator which delivers me each entry and if >>> the creation date is too old i call iterator.remove(). >>> But exactly on this line i get an >>> "java.util.ConcurrentModificationException" although i wrapped all >>> access to the map with synchronized blocks. So every put and get >>> methods are synchronized. >>> >>> >> > --------------------------------------------------------------------- To unsubscribe, e-mail: user-unsubscr...@commons.apache.org For additional commands, e-mail: user-h...@commons.apache.org
