diff --git a/apps/test/intent-perf/src/main/java/org/onosproject/intentperf/IntentPerfInstaller.java b/apps/test/intent-perf/src/main/java/org/onosproject/intentperf/IntentPerfInstaller.java
index e68c13c..8e1ad06 100644
--- a/apps/test/intent-perf/src/main/java/org/onosproject/intentperf/IntentPerfInstaller.java
+++ b/apps/test/intent-perf/src/main/java/org/onosproject/intentperf/IntentPerfInstaller.java
@@ -389,6 +389,9 @@
         return Sets.newHashSet(intents.values());
     }
 
+    final Set<Intent> submitted = Sets.newConcurrentHashSet();
+    final Set<Intent> withdrawn = Sets.newConcurrentHashSet();
+
     // Submits intent operations.
     final class Submitter implements Runnable {
 
@@ -396,8 +399,7 @@
         private int lastCount;
 
         private Set<Intent> intents = Sets.newHashSet();
-        private Set<Intent> submitted = Sets.newHashSet();
-        private Set<Intent> withdrawn = Sets.newHashSet();
+
 
         private Submitter(Set<Intent> intents) {
             this.intents = intents;
@@ -421,20 +423,18 @@
         private Iterable<Intent> subset(Set<Intent> intents) {
             List<Intent> subset = Lists.newArrayList(intents);
             Collections.shuffle(subset);
-            return subset.subList(0, Math.min(intents.size(), lastCount));
+            return subset.subList(0, Math.min(subset.size(), lastCount));
         }
 
         // Submits the specified intent.
         private void submit(Intent intent) {
             intentService.submit(intent);
-            submitted.add(intent);
             withdrawn.remove(intent); //TODO could check result here...
         }
 
         // Withdraws the specified intent.
         private void withdraw(Intent intent) {
             intentService.withdraw(intent);
-            withdrawn.add(intent);
             submitted.remove(intent); //TODO could check result here...
         }
 
@@ -533,6 +533,12 @@
         @Override
         public void event(IntentEvent event) {
             if (event.subject().appId().equals(appId)) {
+                if (event.type() == INSTALLED) {
+                    submitted.add(event.subject());
+                }
+                if (event.type() == WITHDRAWN) {
+                    withdrawn.add(event.subject());
+                }
                 counters.get(event.type()).add(1);
             }
         }