diff --git a/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/authority/AuthorityRuleManager.java b/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/authority/AuthorityRuleManager.java
index da72a226..7962c50e 100755
--- a/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/authority/AuthorityRuleManager.java
+++ b/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/authority/AuthorityRuleManager.java
@@ -16,12 +16,15 @@
 package com.alibaba.csp.sentinel.slots.block.authority;
 
 import java.util.ArrayList;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 
 import com.alibaba.csp.sentinel.log.RecordLog;
 import com.alibaba.csp.sentinel.slots.block.RuleConstant;
+import com.alibaba.csp.sentinel.util.AssertUtil;
 import com.alibaba.csp.sentinel.util.StringUtil;
 import com.alibaba.csp.sentinel.property.DynamicSentinelProperty;
 import com.alibaba.csp.sentinel.property.PropertyListener;
@@ -36,24 +39,22 @@ import com.alibaba.csp.sentinel.property.SentinelProperty;
  */
 public final class AuthorityRuleManager {
 
-    private static Map<String, List<AuthorityRule>> authorityRules
-        = new ConcurrentHashMap<String, List<AuthorityRule>>();
+    private static Map<String, Set<AuthorityRule>> authorityRules = new ConcurrentHashMap<>();
 
-    final static RulePropertyListener listener = new RulePropertyListener();
-
-    private static SentinelProperty<List<AuthorityRule>> currentProperty
-        = new DynamicSentinelProperty<List<AuthorityRule>>();
+    private static final RulePropertyListener LISTENER = new RulePropertyListener();
+    private static SentinelProperty<List<AuthorityRule>> currentProperty = new DynamicSentinelProperty<>();
 
     static {
-        currentProperty.addListener(listener);
+        currentProperty.addListener(LISTENER);
     }
 
     public static void register2Property(SentinelProperty<List<AuthorityRule>> property) {
-        synchronized (listener) {
+        AssertUtil.notNull(property, "property cannot be null");
+        synchronized (LISTENER) {
             if (currentProperty != null) {
-                currentProperty.removeListener(listener);
+                currentProperty.removeListener(LISTENER);
             }
-            property.addListener(listener);
+            property.addListener(LISTENER);
             currentProperty = property;
             RecordLog.info("[AuthorityRuleManager] Registering new property to authority rule manager");
         }
@@ -78,11 +79,11 @@ public final class AuthorityRuleManager {
      * @return a new copy of the rules.
      */
     public static List<AuthorityRule> getRules() {
-        List<AuthorityRule> rules = new ArrayList<AuthorityRule>();
+        List<AuthorityRule> rules = new ArrayList<>();
         if (authorityRules == null) {
             return rules;
         }
-        for (Map.Entry<String, List<AuthorityRule>> entry : authorityRules.entrySet()) {
+        for (Map.Entry<String, Set<AuthorityRule>> entry : authorityRules.entrySet()) {
             rules.addAll(entry.getValue());
         }
         return rules;
@@ -92,7 +93,7 @@ public final class AuthorityRuleManager {
 
         @Override
         public void configUpdate(List<AuthorityRule> conf) {
-            Map<String, List<AuthorityRule>> rules = loadAuthorityConf(conf);
+            Map<String, Set<AuthorityRule>> rules = loadAuthorityConf(conf);
 
             authorityRules.clear();
             if (rules != null) {
@@ -101,8 +102,8 @@ public final class AuthorityRuleManager {
             RecordLog.info("[AuthorityRuleManager] Authority rules received: " + authorityRules);
         }
 
-        private Map<String, List<AuthorityRule>> loadAuthorityConf(List<AuthorityRule> list) {
-            Map<String, List<AuthorityRule>> newRuleMap = new ConcurrentHashMap<String, List<AuthorityRule>>();
+        private Map<String, Set<AuthorityRule>> loadAuthorityConf(List<AuthorityRule> list) {
+            Map<String, Set<AuthorityRule>> newRuleMap = new ConcurrentHashMap<>();
 
             if (list == null || list.isEmpty()) {
                 return newRuleMap;
@@ -119,12 +120,12 @@ public final class AuthorityRuleManager {
                 }
 
                 String identity = rule.getResource();
-                List<AuthorityRule> ruleM = newRuleMap.get(identity);
+                Set<AuthorityRule> ruleSet = newRuleMap.get(identity);
                 // putIfAbsent
-                if (ruleM == null) {
-                    ruleM = new ArrayList<AuthorityRule>();
-                    ruleM.add(rule);
-                    newRuleMap.put(identity, ruleM);
+                if (ruleSet == null) {
+                    ruleSet = new HashSet<>();
+                    ruleSet.add(rule);
+                    newRuleMap.put(identity, ruleSet);
                 } else {
                     // One resource should only have at most one authority rule, so just ignore redundant rules.
                     RecordLog.warn("[AuthorityRuleManager] Ignoring redundant rule: " + rule.toString());
@@ -136,7 +137,7 @@ public final class AuthorityRuleManager {
 
         @Override
         public void configLoad(List<AuthorityRule> value) {
-            Map<String, List<AuthorityRule>> rules = loadAuthorityConf(value);
+            Map<String, Set<AuthorityRule>> rules = loadAuthorityConf(value);
 
             authorityRules.clear();
             if (rules != null) {
@@ -146,11 +147,11 @@ public final class AuthorityRuleManager {
         }
     }
 
-    static Map<String, List<AuthorityRule>> getAuthorityRules() {
+    static Map<String, Set<AuthorityRule>> getAuthorityRules() {
         return authorityRules;
     }
 
-    static boolean isValidRule(AuthorityRule rule) {
+    public static boolean isValidRule(AuthorityRule rule) {
         return rule != null && !StringUtil.isBlank(rule.getResource())
             && rule.getStrategy() >= 0 && StringUtil.isNotBlank(rule.getLimitApp());
     }
diff --git a/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/authority/AuthoritySlot.java b/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/authority/AuthoritySlot.java
index 369699c9..f7920baa 100755
--- a/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/authority/AuthoritySlot.java
+++ b/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/authority/AuthoritySlot.java
@@ -15,8 +15,8 @@
  */
 package com.alibaba.csp.sentinel.slots.block.authority;
 
-import java.util.List;
 import java.util.Map;
+import java.util.Set;
 
 import com.alibaba.csp.sentinel.context.Context;
 import com.alibaba.csp.sentinel.node.DefaultNode;
@@ -45,13 +45,13 @@ public class AuthoritySlot extends AbstractLinkedProcessorSlot<DefaultNode> {
     }
 
     void checkBlackWhiteAuthority(ResourceWrapper resource, Context context) throws AuthorityException {
-        Map<String, List<AuthorityRule>> authorityRules = AuthorityRuleManager.getAuthorityRules();
+        Map<String, Set<AuthorityRule>> authorityRules = AuthorityRuleManager.getAuthorityRules();
 
         if (authorityRules == null) {
             return;
         }
 
-        List<AuthorityRule> rules = authorityRules.get(resource.getName());
+        Set<AuthorityRule> rules = authorityRules.get(resource.getName());
         if (rules == null) {
             return;
         }
diff --git a/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/degrade/DegradeRuleManager.java b/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/degrade/DegradeRuleManager.java
index 5da818fa..9eb7e582 100755
--- a/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/degrade/DegradeRuleManager.java
+++ b/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/degrade/DegradeRuleManager.java
@@ -16,10 +16,14 @@
 package com.alibaba.csp.sentinel.slots.block.degrade;
 
 import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 
+import com.alibaba.csp.sentinel.Constants;
 import com.alibaba.csp.sentinel.context.Context;
 import com.alibaba.csp.sentinel.log.RecordLog;
 import com.alibaba.csp.sentinel.node.DefaultNode;
@@ -29,23 +33,24 @@ import com.alibaba.csp.sentinel.property.SentinelProperty;
 import com.alibaba.csp.sentinel.slotchain.ResourceWrapper;
 import com.alibaba.csp.sentinel.slots.block.BlockException;
 import com.alibaba.csp.sentinel.slots.block.RuleConstant;
+import com.alibaba.csp.sentinel.util.AssertUtil;
 import com.alibaba.csp.sentinel.util.StringUtil;
 
-/***
+/**
  * @author youji.zj
  * @author jialiang.linjl
+ * @author Eric Zhao
  */
-public class DegradeRuleManager {
+public final class DegradeRuleManager {
 
-    private static volatile Map<String, List<DegradeRule>> degradeRules
-        = new ConcurrentHashMap<String, List<DegradeRule>>();
+    private static final Map<String, Set<DegradeRule>> degradeRules = new ConcurrentHashMap<>();
 
-    final static RulePropertyListener listener = new RulePropertyListener();
+    private static final RulePropertyListener LISTENER = new RulePropertyListener();
     private static SentinelProperty<List<DegradeRule>> currentProperty
-        = new DynamicSentinelProperty<List<DegradeRule>>();
+        = new DynamicSentinelProperty<>();
 
     static {
-        currentProperty.addListener(listener);
+        currentProperty.addListener(LISTENER);
     }
 
     /**
@@ -55,21 +60,19 @@ public class DegradeRuleManager {
      * @param property the property to listen.
      */
     public static void register2Property(SentinelProperty<List<DegradeRule>> property) {
-        synchronized (listener) {
+        AssertUtil.notNull(property, "property cannot be null");
+        synchronized (LISTENER) {
             RecordLog.info("[DegradeRuleManager] Registering new property to degrade rule manager");
-            currentProperty.removeListener(listener);
-            property.addListener(listener);
+            currentProperty.removeListener(LISTENER);
+            property.addListener(LISTENER);
             currentProperty = property;
         }
     }
 
     public static void checkDegrade(ResourceWrapper resource, Context context, DefaultNode node, int count)
         throws BlockException {
-        if (degradeRules == null) {
-            return;
-        }
 
-        List<DegradeRule> rules = degradeRules.get(resource.getName());
+        Set<DegradeRule> rules = degradeRules.get(resource.getName());
         if (rules == null) {
             return;
         }
@@ -82,6 +85,9 @@ public class DegradeRuleManager {
     }
 
     public static boolean hasConfig(String resource) {
+        if (resource == null) {
+            return false;
+        }
         return degradeRules.containsKey(resource);
     }
 
@@ -91,11 +97,8 @@ public class DegradeRuleManager {
      * @return a new copy of the rules.
      */
     public static List<DegradeRule> getRules() {
-        List<DegradeRule> rules = new ArrayList<DegradeRule>();
-        if (degradeRules == null) {
-            return rules;
-        }
-        for (Map.Entry<String, List<DegradeRule>> entry : degradeRules.entrySet()) {
+        List<DegradeRule> rules = new ArrayList<>();
+        for (Map.Entry<String, Set<DegradeRule>> entry : degradeRules.entrySet()) {
             rules.addAll(entry.getValue());
         }
         return rules;
@@ -110,7 +113,42 @@ public class DegradeRuleManager {
         try {
             currentProperty.updateValue(rules);
         } catch (Throwable e) {
-            RecordLog.info(e.getMessage(), e);
+            RecordLog.warn("[DegradeRuleManager] Unexpected error when loading degrade rules", e);
+        }
+    }
+
+    /**
+     * Set degrade rules for provided resource. Former rules of the resource will be replaced.
+     *
+     * @param resourceName valid resource name
+     * @param rules        new rule set to load
+     * @return whether the rules has actually been updated
+     * @since 1.5.0
+     */
+    public static boolean setRulesForResource(String resourceName, Set<DegradeRule> rules) {
+        AssertUtil.notEmpty(resourceName, "resourceName cannot be empty");
+        try {
+            Map<String, Set<DegradeRule>> newRuleMap = new HashMap<>(degradeRules);
+            if (rules == null) {
+                newRuleMap.remove(resourceName);
+            } else {
+                Set<DegradeRule> newSet = new HashSet<>();
+                for (DegradeRule rule : rules) {
+                    if (isValidRule(rule) && resourceName.equals(rule.getResource())) {
+                        newSet.add(rule);
+                    }
+                }
+                newRuleMap.put(resourceName, newSet);
+            }
+            List<DegradeRule> allRules = new ArrayList<>();
+            for (Set<DegradeRule> set : newRuleMap.values()) {
+                allRules.addAll(set);
+            }
+            return currentProperty.updateValue(allRules);
+        } catch (Throwable e) {
+            RecordLog.warn(
+                "[DegradeRuleManager] Unexpected error when setting degrade rules for resource: " + resourceName, e);
+            return false;
         }
     }
 
@@ -118,7 +156,7 @@ public class DegradeRuleManager {
 
         @Override
         public void configUpdate(List<DegradeRule> conf) {
-            Map<String, List<DegradeRule>> rules = loadDegradeConf(conf);
+            Map<String, Set<DegradeRule>> rules = loadDegradeConf(conf);
             if (rules != null) {
                 degradeRules.clear();
                 degradeRules.putAll(rules);
@@ -128,7 +166,7 @@ public class DegradeRuleManager {
 
         @Override
         public void configLoad(List<DegradeRule> conf) {
-            Map<String, List<DegradeRule>> rules = loadDegradeConf(conf);
+            Map<String, Set<DegradeRule>> rules = loadDegradeConf(conf);
             if (rules != null) {
                 degradeRules.clear();
                 degradeRules.putAll(rules);
@@ -136,8 +174,8 @@ public class DegradeRuleManager {
             RecordLog.info("[DegradeRuleManager] Degrade rules loaded: " + degradeRules);
         }
 
-        private Map<String, List<DegradeRule>> loadDegradeConf(List<DegradeRule> list) {
-            Map<String, List<DegradeRule>> newRuleMap = new ConcurrentHashMap<String, List<DegradeRule>>();
+        private Map<String, Set<DegradeRule>> loadDegradeConf(List<DegradeRule> list) {
+            Map<String, Set<DegradeRule>> newRuleMap = new ConcurrentHashMap<>();
 
             if (list == null || list.isEmpty()) {
                 return newRuleMap;
@@ -145,7 +183,8 @@ public class DegradeRuleManager {
 
             for (DegradeRule rule : list) {
                 if (!isValidRule(rule)) {
-                    RecordLog.warn("[DegradeRuleManager] Ignoring invalid degrade rule when loading new rules: " + rule);
+                    RecordLog.warn(
+                        "[DegradeRuleManager] Ignoring invalid degrade rule when loading new rules: " + rule);
                     continue;
                 }
 
@@ -154,17 +193,16 @@ public class DegradeRuleManager {
                 }
 
                 String identity = rule.getResource();
-                List<DegradeRule> ruleM = newRuleMap.get(identity);
-                if (ruleM == null) {
-                    ruleM = new ArrayList<DegradeRule>();
-                    newRuleMap.put(identity, ruleM);
+                Set<DegradeRule> ruleSet = newRuleMap.get(identity);
+                if (ruleSet == null) {
+                    ruleSet = new HashSet<>();
+                    newRuleMap.put(identity, ruleSet);
                 }
-                ruleM.add(rule);
+                ruleSet.add(rule);
             }
 
             return newRuleMap;
         }
-
     }
 
     public static boolean isValidRule(DegradeRule rule) {
@@ -173,6 +211,13 @@ public class DegradeRuleManager {
         if (!baseValid) {
             return false;
         }
+        // Warn for RT mode that exceeds the {@code TIME_DROP_VALVE}.
+        int maxAllowedRt = Constants.TIME_DROP_VALVE;
+        if (rule.getGrade() == RuleConstant.DEGRADE_GRADE_RT && rule.getCount() > maxAllowedRt) {
+            RecordLog.warn(String.format("[DegradeRuleManager] WARN: setting large RT threshold (%.1f ms) in RT mode"
+                    + " will not take effect since it exceeds the max allowed value (%d ms)", rule.getCount(),
+                maxAllowedRt));
+        }
         // Check exception ratio mode.
         if (rule.getGrade() == RuleConstant.DEGRADE_GRADE_EXCEPTION_RATIO && rule.getCount() > 1) {
             return false;
diff --git a/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/flow/FlowRuleManager.java b/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/flow/FlowRuleManager.java
index 9dd23026..18885812 100755
--- a/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/flow/FlowRuleManager.java
+++ b/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/flow/FlowRuleManager.java
@@ -25,6 +25,7 @@ import java.util.concurrent.TimeUnit;
 
 import com.alibaba.csp.sentinel.concurrent.NamedThreadFactory;
 import com.alibaba.csp.sentinel.log.RecordLog;
+import com.alibaba.csp.sentinel.util.AssertUtil;
 import com.alibaba.csp.sentinel.util.StringUtil;
 import com.alibaba.csp.sentinel.node.metric.MetricTimerListener;
 import com.alibaba.csp.sentinel.property.DynamicSentinelProperty;
@@ -65,6 +66,7 @@ public class FlowRuleManager {
      * @param property the property to listen.
      */
     public static void register2Property(SentinelProperty<List<FlowRule>> property) {
+        AssertUtil.notNull(property, "property cannot be null");
         synchronized (LISTENER) {
             RecordLog.info("[FlowRuleManager] Registering new property to flow rule manager");
             currentProperty.removeListener(LISTENER);
diff --git a/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/flow/FlowRuleUtil.java b/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/flow/FlowRuleUtil.java
index 9d61229e..2c776d15 100644
--- a/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/flow/FlowRuleUtil.java
+++ b/sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/flow/FlowRuleUtil.java
@@ -18,8 +18,11 @@ package com.alibaba.csp.sentinel.slots.block.flow;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 
 import com.alibaba.csp.sentinel.log.RecordLog;
@@ -85,10 +88,11 @@ public final class FlowRuleUtil {
      */
     public static <K> Map<K, List<FlowRule>> buildFlowRuleMap(List<FlowRule> list, Function<FlowRule, K> groupFunction,
                                                               Predicate<FlowRule> filter, boolean shouldSort) {
-        Map<K, List<FlowRule>> newRuleMap = new ConcurrentHashMap<K, List<FlowRule>>();
+        Map<K, List<FlowRule>> newRuleMap = new ConcurrentHashMap<>();
         if (list == null || list.isEmpty()) {
             return newRuleMap;
         }
+        Map<K, Set<FlowRule>> tmpMap = new ConcurrentHashMap<>();
 
         for (FlowRule rule : list) {
             if (!isValidRule(rule)) {
@@ -109,22 +113,24 @@ public final class FlowRuleUtil {
             if (key == null) {
                 continue;
             }
-            List<FlowRule> flowRules = newRuleMap.get(key);
+            Set<FlowRule> flowRules = tmpMap.get(key);
 
             if (flowRules == null) {
-                flowRules = new ArrayList<FlowRule>();
-                newRuleMap.put(key, flowRules);
+                // Use hash set here to remove duplicate rules.
+                flowRules = new HashSet<>();
+                tmpMap.put(key, flowRules);
             }
 
             flowRules.add(rule);
         }
-
-        if (shouldSort && !newRuleMap.isEmpty()) {
-            Comparator<FlowRule> comparator = new FlowRuleComparator();
-            // Sort the rules.
-            for (List<FlowRule> rules : newRuleMap.values()) {
+        Comparator<FlowRule> comparator = new FlowRuleComparator();
+        for (Entry<K, Set<FlowRule>> entries : tmpMap.entrySet()) {
+            List<FlowRule> rules = new ArrayList<>(entries.getValue());
+            if (shouldSort) {
+                // Sort the rules.
                 Collections.sort(rules, comparator);
             }
+            newRuleMap.put(entries.getKey(), rules);
         }
 
         return newRuleMap;
diff --git a/sentinel-extension/sentinel-parameter-flow-control/src/main/java/com/alibaba/csp/sentinel/slots/block/flow/param/ParamFlowRuleManager.java b/sentinel-extension/sentinel-parameter-flow-control/src/main/java/com/alibaba/csp/sentinel/slots/block/flow/param/ParamFlowRuleManager.java
index dcd2c01f..40c923b5 100644
--- a/sentinel-extension/sentinel-parameter-flow-control/src/main/java/com/alibaba/csp/sentinel/slots/block/flow/param/ParamFlowRuleManager.java
+++ b/sentinel-extension/sentinel-parameter-flow-control/src/main/java/com/alibaba/csp/sentinel/slots/block/flow/param/ParamFlowRuleManager.java
@@ -16,6 +16,7 @@
 package com.alibaba.csp.sentinel.slots.block.flow.param;
 
 import java.util.ArrayList;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -26,6 +27,7 @@ import com.alibaba.csp.sentinel.property.DynamicSentinelProperty;
 import com.alibaba.csp.sentinel.property.PropertyListener;
 import com.alibaba.csp.sentinel.property.SentinelProperty;
 import com.alibaba.csp.sentinel.slots.block.RuleConstant;
+import com.alibaba.csp.sentinel.util.AssertUtil;
 import com.alibaba.csp.sentinel.util.StringUtil;
 
 /**
@@ -37,12 +39,10 @@ import com.alibaba.csp.sentinel.util.StringUtil;
  */
 public final class ParamFlowRuleManager {
 
-    private static final Map<String, List<ParamFlowRule>> paramFlowRules
-        = new ConcurrentHashMap<String, List<ParamFlowRule>>();
+    private static final Map<String, Set<ParamFlowRule>> paramFlowRules = new ConcurrentHashMap<>();
 
     private final static RulePropertyListener PROPERTY_LISTENER = new RulePropertyListener();
-    private static SentinelProperty<List<ParamFlowRule>> currentProperty
-        = new DynamicSentinelProperty<List<ParamFlowRule>>();
+    private static SentinelProperty<List<ParamFlowRule>> currentProperty = new DynamicSentinelProperty<>();
 
     static {
         currentProperty.addListener(PROPERTY_LISTENER);
@@ -68,6 +68,7 @@ public final class ParamFlowRuleManager {
      * @param property the property to listen
      */
     public static void register2Property(SentinelProperty<List<ParamFlowRule>> property) {
+        AssertUtil.notNull(property, "property cannot be null");
         synchronized (PROPERTY_LISTENER) {
             currentProperty.removeListener(PROPERTY_LISTENER);
             property.addListener(PROPERTY_LISTENER);
@@ -77,11 +78,11 @@ public final class ParamFlowRuleManager {
     }
 
     public static List<ParamFlowRule> getRulesOfResource(String resourceName) {
-        return paramFlowRules.get(resourceName);
+        return new ArrayList<>(paramFlowRules.get(resourceName));
     }
 
     public static boolean hasRules(String resourceName) {
-        List<ParamFlowRule> rules = paramFlowRules.get(resourceName);
+        Set<ParamFlowRule> rules = paramFlowRules.get(resourceName);
         return rules != null && !rules.isEmpty();
     }
 
@@ -91,8 +92,8 @@ public final class ParamFlowRuleManager {
      * @return a new copy of the rules.
      */
     public static List<ParamFlowRule> getRules() {
-        List<ParamFlowRule> rules = new ArrayList<ParamFlowRule>();
-        for (Map.Entry<String, List<ParamFlowRule>> entry : paramFlowRules.entrySet()) {
+        List<ParamFlowRule> rules = new ArrayList<>();
+        for (Map.Entry<String, Set<ParamFlowRule>> entry : paramFlowRules.entrySet()) {
             rules.addAll(entry.getValue());
         }
         return rules;
@@ -102,7 +103,7 @@ public final class ParamFlowRuleManager {
 
         @Override
         public void configUpdate(List<ParamFlowRule> list) {
-            Map<String, List<ParamFlowRule>> rules = aggregateHotParamRules(list);
+            Map<String, Set<ParamFlowRule>> rules = aggregateHotParamRules(list);
             if (rules != null) {
                 paramFlowRules.clear();
                 paramFlowRules.putAll(rules);
@@ -112,7 +113,7 @@ public final class ParamFlowRuleManager {
 
         @Override
         public void configLoad(List<ParamFlowRule> list) {
-            Map<String, List<ParamFlowRule>> rules = aggregateHotParamRules(list);
+            Map<String, Set<ParamFlowRule>> rules = aggregateHotParamRules(list);
             if (rules != null) {
                 paramFlowRules.clear();
                 paramFlowRules.putAll(rules);
@@ -120,8 +121,8 @@ public final class ParamFlowRuleManager {
             RecordLog.info("[ParamFlowRuleManager] Hot spot parameter flow rules received: " + paramFlowRules);
         }
 
-        private Map<String, List<ParamFlowRule>> aggregateHotParamRules(List<ParamFlowRule> list) {
-            Map<String, List<ParamFlowRule>> newRuleMap = new ConcurrentHashMap<String, List<ParamFlowRule>>();
+        private Map<String, Set<ParamFlowRule>> aggregateHotParamRules(List<ParamFlowRule> list) {
+            Map<String, Set<ParamFlowRule>> newRuleMap = new ConcurrentHashMap<>();
 
             if (list == null || list.isEmpty()) {
                 // No parameter flow rules, so clear all the metrics.
@@ -143,12 +144,12 @@ public final class ParamFlowRuleManager {
                 ParamFlowRuleUtil.fillExceptionFlowItems(rule);
 
                 String resourceName = rule.getResource();
-                List<ParamFlowRule> ruleList = newRuleMap.get(resourceName);
-                if (ruleList == null) {
-                    ruleList = new ArrayList<ParamFlowRule>();
-                    newRuleMap.put(resourceName, ruleList);
+                Set<ParamFlowRule> ruleSet = newRuleMap.get(resourceName);
+                if (ruleSet == null) {
+                    ruleSet = new HashSet<>();
+                    newRuleMap.put(resourceName, ruleSet);
                 }
-                ruleList.add(rule);
+                ruleSet.add(rule);
             }
 
             // Clear unused hot param metrics.