diff --git a/tomcat-core/src/main/java/com/hazelcast/session/LocalSessionsInvalidateListener.java b/tomcat-core/src/main/java/com/hazelcast/session/LocalSessionsInvalidateListener.java
new file mode 100644
index 0000000..eba129b
--- /dev/null
+++ b/tomcat-core/src/main/java/com/hazelcast/session/LocalSessionsInvalidateListener.java
@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2008-2019, Hazelcast, Inc. All Rights Reserved.
+ */
+
+package com.hazelcast.session;
+
+import com.hazelcast.core.EntryEvent;
+import com.hazelcast.map.listener.EntryEvictedListener;
+import com.hazelcast.map.listener.EntryRemovedListener;
+import org.apache.catalina.Session;
+
+import java.util.Map;
+
+public class LocalSessionsInvalidateListener implements EntryEvictedListener<String, HazelcastSession>,
+        EntryRemovedListener<String, HazelcastSession> {
+
+    private Map<String, Session> sessions;
+
+    public LocalSessionsInvalidateListener(Map<String, Session> sessions) {
+        this.sessions = sessions;
+    }
+
+    @Override
+    public void entryEvicted(EntryEvent<String, HazelcastSession> event) {
+        invalidateSessions(event);
+    }
+
+    @Override
+    public void entryRemoved(EntryEvent<String, HazelcastSession> event) {
+        invalidateSessions(event);
+    }
+
+    private void invalidateSessions(EntryEvent<String, HazelcastSession> entryEvent) {
+        if (entryEvent.getMember() == null || !entryEvent.getMember().localMember()) {
+            sessions.remove(entryEvent.getKey());
+        }
+    }
+}
diff --git a/tomcat6/src/main/java/com/hazelcast/session/HazelcastSessionManager.java b/tomcat6/src/main/java/com/hazelcast/session/HazelcastSessionManager.java
index ff8086d..d427cdf 100644
--- a/tomcat6/src/main/java/com/hazelcast/session/HazelcastSessionManager.java
+++ b/tomcat6/src/main/java/com/hazelcast/session/HazelcastSessionManager.java
@@ -4,11 +4,8 @@
 
 package com.hazelcast.session;
 
-import com.hazelcast.core.EntryEvent;
-import com.hazelcast.core.EntryListener;
 import com.hazelcast.core.HazelcastInstance;
 import com.hazelcast.core.IMap;
-import com.hazelcast.core.MapEvent;
 import org.apache.catalina.Context;
 import org.apache.catalina.Lifecycle;
 import org.apache.catalina.LifecycleException;
@@ -124,29 +121,7 @@ public void start() throws LifecycleException {
         }
 
         if (!isSticky()) {
-            sessionMap.addEntryListener(new EntryListener<String, HazelcastSession>() {
-                public void entryAdded(EntryEvent<String, HazelcastSession> event) {
-                }
-
-                public void entryRemoved(EntryEvent<String, HazelcastSession> entryEvent) {
-                    if (entryEvent.getMember() == null || !entryEvent.getMember().localMember()) {
-                        sessions.remove(entryEvent.getKey());
-                    }
-                }
-
-                public void entryUpdated(EntryEvent<String, HazelcastSession> event) {
-                }
-
-                public void entryEvicted(EntryEvent<String, HazelcastSession> entryEvent) {
-                    entryRemoved(entryEvent);
-                }
-
-                public void mapEvicted(MapEvent event) {
-                }
-
-                public void mapCleared(MapEvent event) {
-                }
-            }, false);
+            sessionMap.addEntryListener(new LocalSessionsInvalidateListener(sessions), false);
         }
 
         log.info("HazelcastSessionManager started...");
@@ -238,8 +213,14 @@ public Session findSession(String id) throws IOException {
             sessions.put(id, hazelcastSession);
 
             // call remove method to trigger eviction Listener on each node to invalidate local sessions
-            sessionMap.remove(id);
-            sessionMap.set(id, hazelcastSession);
+            // the call are performed in a pessimistic lock block to prevent concurrency problems whilst finding sessions
+            sessionMap.lock(id);
+            try {
+                sessionMap.remove(id);
+                sessionMap.set(id, hazelcastSession);
+            } finally {
+                sessionMap.unlock(id);
+            }
 
             return hazelcastSession;
 
diff --git a/tomcat7/src/main/java/com/hazelcast/session/HazelcastSessionManager.java b/tomcat7/src/main/java/com/hazelcast/session/HazelcastSessionManager.java
index 10c32af..ea33184 100644
--- a/tomcat7/src/main/java/com/hazelcast/session/HazelcastSessionManager.java
+++ b/tomcat7/src/main/java/com/hazelcast/session/HazelcastSessionManager.java
@@ -4,11 +4,8 @@
 
 package com.hazelcast.session;
 
-import com.hazelcast.core.EntryEvent;
-import com.hazelcast.core.EntryListener;
 import com.hazelcast.core.HazelcastInstance;
 import com.hazelcast.core.IMap;
-import com.hazelcast.core.MapEvent;
 import org.apache.catalina.Context;
 import org.apache.catalina.Lifecycle;
 import org.apache.catalina.LifecycleException;
@@ -111,29 +108,7 @@ public void startInternal() throws LifecycleException {
         }
 
         if (!isSticky()) {
-            sessionMap.addEntryListener(new EntryListener<String, HazelcastSession>() {
-                public void entryAdded(EntryEvent<String, HazelcastSession> event) {
-                }
-
-                public void entryRemoved(EntryEvent<String, HazelcastSession> entryEvent) {
-                    if (entryEvent.getMember() == null || !entryEvent.getMember().localMember()) {
-                        sessions.remove(entryEvent.getKey());
-                    }
-                }
-
-                public void entryUpdated(EntryEvent<String, HazelcastSession> event) {
-                }
-
-                public void entryEvicted(EntryEvent<String, HazelcastSession> entryEvent) {
-                    entryRemoved(entryEvent);
-                }
-
-                public void mapEvicted(MapEvent event) {
-                }
-
-                public void mapCleared(MapEvent event) {
-                }
-            }, false);
+            sessionMap.addEntryListener(new LocalSessionsInvalidateListener(sessions), false);
         }
 
         log.info("HazelcastSessionManager started...");
@@ -237,8 +212,14 @@ public Session findSession(String id) throws IOException {
             sessions.put(id, hazelcastSession);
 
             // call remove method to trigger eviction Listener on each node to invalidate local sessions
-            sessionMap.remove(id);
-            sessionMap.set(id, hazelcastSession);
+            // the call are performed in a pessimistic lock block to prevent concurrency problems whilst finding sessions
+            sessionMap.lock(id);
+            try {
+                sessionMap.remove(id);
+                sessionMap.set(id, hazelcastSession);
+            } finally {
+                sessionMap.unlock(id);
+            }
 
             return hazelcastSession;
         } else {
diff --git a/tomcat8/src/main/java/com/hazelcast/session/HazelcastSessionManager.java b/tomcat8/src/main/java/com/hazelcast/session/HazelcastSessionManager.java
index 531298c..64715c2 100644
--- a/tomcat8/src/main/java/com/hazelcast/session/HazelcastSessionManager.java
+++ b/tomcat8/src/main/java/com/hazelcast/session/HazelcastSessionManager.java
@@ -4,11 +4,8 @@
 
 package com.hazelcast.session;
 
-import com.hazelcast.core.EntryEvent;
-import com.hazelcast.core.EntryListener;
 import com.hazelcast.core.HazelcastInstance;
 import com.hazelcast.core.IMap;
-import com.hazelcast.core.MapEvent;
 import org.apache.catalina.Context;
 import org.apache.catalina.Lifecycle;
 import org.apache.catalina.LifecycleException;
@@ -109,29 +106,7 @@ public void startInternal() throws LifecycleException {
         }
 
         if (!isSticky()) {
-            sessionMap.addEntryListener(new EntryListener<String, HazelcastSession>() {
-                public void entryAdded(EntryEvent<String, HazelcastSession> event) {
-                }
-
-                public void entryRemoved(EntryEvent<String, HazelcastSession> entryEvent) {
-                    if (entryEvent.getMember() == null || !entryEvent.getMember().localMember()) {
-                        sessions.remove(entryEvent.getKey());
-                    }
-                }
-
-                public void entryUpdated(EntryEvent<String, HazelcastSession> event) {
-                }
-
-                public void entryEvicted(EntryEvent<String, HazelcastSession> entryEvent) {
-                    entryRemoved(entryEvent);
-                }
-
-                public void mapEvicted(MapEvent event) {
-                }
-
-                public void mapCleared(MapEvent event) {
-                }
-            }, false);
+            sessionMap.addEntryListener(new LocalSessionsInvalidateListener(sessions), false);
         }
 
         log.info("HazelcastSessionManager started...");
@@ -235,8 +210,14 @@ public Session findSession(String id) throws IOException {
             sessions.put(id, hazelcastSession);
 
             // call remove method to trigger eviction Listener on each node to invalidate local sessions
-            sessionMap.remove(id);
-            sessionMap.set(id, hazelcastSession);
+            // the call are performed in a pessimistic lock block to prevent concurrency problems whilst finding sessions
+            sessionMap.lock(id);
+            try {
+                sessionMap.remove(id);
+                sessionMap.set(id, hazelcastSession);
+            } finally {
+                sessionMap.unlock(id);
+            }
 
             return hazelcastSession;
         } else {
diff --git a/tomcat85/src/main/java/com/hazelcast/session/HazelcastSessionManager.java b/tomcat85/src/main/java/com/hazelcast/session/HazelcastSessionManager.java
index 87a1a20..e39ccb4 100644
--- a/tomcat85/src/main/java/com/hazelcast/session/HazelcastSessionManager.java
+++ b/tomcat85/src/main/java/com/hazelcast/session/HazelcastSessionManager.java
@@ -4,11 +4,8 @@
 
 package com.hazelcast.session;
 
-import com.hazelcast.core.EntryEvent;
-import com.hazelcast.core.EntryListener;
 import com.hazelcast.core.HazelcastInstance;
 import com.hazelcast.core.IMap;
-import com.hazelcast.core.MapEvent;
 import org.apache.catalina.Context;
 import org.apache.catalina.Lifecycle;
 import org.apache.catalina.LifecycleException;
@@ -91,29 +88,7 @@ public void startInternal() throws LifecycleException {
         }
 
         if (!isSticky()) {
-            sessionMap.addEntryListener(new EntryListener<String, HazelcastSession>() {
-                public void entryAdded(EntryEvent<String, HazelcastSession> event) {
-                }
-
-                public void entryRemoved(EntryEvent<String, HazelcastSession> entryEvent) {
-                    if (entryEvent.getMember() == null || !entryEvent.getMember().localMember()) {
-                        sessions.remove(entryEvent.getKey());
-                    }
-                }
-
-                public void entryUpdated(EntryEvent<String, HazelcastSession> event) {
-                }
-
-                public void entryEvicted(EntryEvent<String, HazelcastSession> entryEvent) {
-                    entryRemoved(entryEvent);
-                }
-
-                public void mapEvicted(MapEvent event) {
-                }
-
-                public void mapCleared(MapEvent event) {
-                }
-            }, false);
+            sessionMap.addEntryListener(new LocalSessionsInvalidateListener(sessions), false);
         }
 
         log.info("HazelcastSessionManager started...");
@@ -220,8 +195,14 @@ public Session findSession(String id) throws IOException {
             sessions.put(id, hazelcastSession);
 
             // call remove method to trigger eviction Listener on each node to invalidate local sessions
-            sessionMap.remove(id);
-            sessionMap.set(id, hazelcastSession);
+            // the call are performed in a pessimistic lock block to prevent concurrency problems whilst finding sessions
+            sessionMap.lock(id);
+            try {
+                sessionMap.remove(id);
+                sessionMap.set(id, hazelcastSession);
+            } finally {
+                sessionMap.unlock(id);
+            }
 
             return hazelcastSession;
         } else {