JBoss development, A new message was posted in the thread "Profiling the dependency project": http://community.jboss.org/message/525220#525220 Author : Kabir Khan Profile : http://community.jboss.org/people/kabir.khan@jboss.com Message: -------------------------------------------------------------- What I forgot to mention here is that the perfomance of these sets is related to the size. COWAS performs better than ConcurrentSet when a small number of exisiting entries are present, which probably makes it ok for the 'installing' set since that will not contain that many entries. It does however degrade its performance rapidly when there are many entries there, so it is probably not the best choice for the sets stored in 'contextsByState'.   This little test demonstrates the difference: public class SetBenchmark {    static int prefill = 1000;       static int iterations = 10000000;       public static void main(String[] args)    {       Set<String> set = new CopyOnWriteArraySet<String>(); //      Set<String> set = new ConcurrentSet(); //      Set<String> set = new HashSet<String>(); //      Set<String> set = new ConcurrentSkipListSet<String>();             for (int i = 0 ; i < prefill ; i++)       {          set.add("XYZ" + i);       }             long start = System.currentTimeMillis();       for (int i = 0 ; i < iterations ; i++)       {          set.add("XXX" + i);          set.remove("XXX" + i);       }       System.out.println("-----> " + (System.currentTimeMillis() - start));    } }   The times in ms for various amounts of prefill, COWAS, normal HashSet, ConcurrentSkipListSet and ConcurrentSet:   So this might explain why CS makes performance worse when used for contextsByState's sets, in my benchmark most states will have very few entries and only a few willl have lots of entries. CSLS always seems to be slower than CS so we won't go with that.   A few of Jason's suggestions were; - Create own COWAS implementation based on FastCopyHashMap - Try a normal synchronized HashSet (need to make sure first that the way we use it we don't iterate over the entries) - ConcurrentSkipListMap although its performance degrades with performance (evaluated above) -------------------------------------------------------------- To reply to this message visit the message page: http://community.jboss.org/message/525220#525220