Hi guys, I have a questions regarding how to maintain the performance as the rule engine fresh restarted when using stateless sessions (with drools 4.0.3). We use drools in a web server to filter out unwanted facts coming from each request. There are about 20 rules, but each request can have 500 to 2000 facts. We are trying to serve 10+ requests concurrently. Since it is pure filtering, we use stateless sessions, with a singleton ruleBase; the sequencial is set TRUE. We do remove the unwanted facts in our rules (RHS), for example: rule "Locale Restrictions" when $actionCollection : ActionFacts () $scoredAction : ScoredAction ( action.type == TYPE.LOCAL ) from $actionCollection.scoredActions $country : Country () eval ( $country != Country.UNITED_STATES ) then if (logger.isDebugEnabled()) { logger.debug("remove action " + $scoredAction.getAction() + " from action list because country is " + $country); } modifyRetract($actionCollection); $actionCollection.getScoredActions().remove($scoredAction); modifyInsert($actionCollection); end Every time we get a request, we file the rules like this: ruleBase.newStatelessSession().execute(facts). The problem is, when the rules engine just starts, it is very fast; on average it can process 2 facts in 1 ms ( -- great work, guys!). However, after a while ( a few thousands requests), it is slowing down; on average processing each fact will take about 2 to 5 ms (4x to 10x slower). Since we use stateless sessions, I expect the initial performance should be maintained overtime. I did a thread dump, and found some threads in drools are blocked (in a fresh restarted rule engine, I don't see these blockings): Thread 20582: (state = BLOCKED) - java.lang.Class.forName0(java.lang.String, boolean, java.lang.ClassLoader) @bci=0 (Compiled frame; information may be imprecise) - java.lang.Class.forName(java.lang.String) @bci=5, line=169 (Compiled frame) - org.mvel.util.ParseTools.resolveType(java.lang.Class) @bci=256, line=696 (Compiled frame) - org.mvel.math.IEEEFloatingPointMath.doOperation(java.lang.Object, int, java.lang.Object) @bci=29, line=24 (Compiled frame) - org.mvel.util.ParseTools.doOperations(java.lang.Object, int, java.lang.Object) @bci=6, line=767 (Compiled frame) - org.mvel.ast.BinaryOperation.getReducedValueAccelerated(java.lang.Object, java.lang.Object, org.mvel.integration.VariableResolverFactory) @bci=24, line=20 (Compiled frame) - org.mvel.MVELRuntime.execute(boolean, org.mvel.CompiledExpression, java.lang.Object, org.mvel.integration.VariableResolverFactory) @bci=134, line=88 (Compiled frame) - org.mvel.CompiledExpression.getValue(java.lang.Object, org.mvel.integration.VariableResolverFactory) @bci=15, line=108 (Compiled frame) - org.mvel.MVEL.executeExpression(java.lang.Object, java.lang.Object, org.mvel.integration.VariableResolverFactory) @bci=6, line=230 (Compiled frame) - org.drools.base.mvel.MVELPredicateExpression.evaluate(java.lang.Object, org.drools.spi.Tuple, org.drools.rule.Declaration[], org.drools.rule.Declaration[], org.drools.WorkingMemory) @bci=22, line=36 (Compiled frame) - org.drools.rule.PredicateConstraint.isAllowed(java.lang.Object, org.drools.common.InternalWorkingMemory) @bci=15, line=210 (Compiled frame) - org.drools.reteoo.FromNode.assertTuple(org.drools.reteoo.ReteTuple, org.drools.spi.PropagationContext, org.drools.common.InternalWorkingMemory) @bci=113, line=73 (Compiled frame) - org.drools.reteoo.CompositeTupleSinkAdapter.createAndPropagateAssertTuple(org.drools.common.InternalFactHandle, org.drools.spi.PropagationContext, org.drools.common.InternalWorkingMemory) @bci=26, line=73 (Compiled frame) - org.drools.reteoo.LIANodePropagation.doPropagation(org.drools.common.InternalWorkingMemory) @bci=16, line=22 (Interpreted frame) - org.drools.common.AbstractWorkingMemory.fireAllRules(org.drools.spi.AgendaFilter, int) @bci=41, line=448 (Compiled frame) - org.drools.common.AbstractWorkingMemory.fireAllRules(org.drools.spi.AgendaFilter) @bci=3, line=434 (Compiled frame) - org.drools.reteoo.ReteooStatelessSession.execute(java.util.Collection) @bci=42, line=162 (Compiled frame) My question is, is there something buit-up in the stateless session? how to maintain the initial performance effectively? Any suggestion is highly appreciated. thanks -- View this message in context: http://www.nabble.com/Performance-Question-with-Stateless-Session-tp14704... Sent from the drools - user mailing list archive at Nabble.com.