diff --git a/src/main/java/org/gcube/portal/oidc/lr62/IntraVMJWTCacheProxy.java b/src/main/java/org/gcube/portal/oidc/lr62/IntraVMJWTCacheProxy.java
index 7ffefde..b3e163b 100644
--- a/src/main/java/org/gcube/portal/oidc/lr62/IntraVMJWTCacheProxy.java
+++ b/src/main/java/org/gcube/portal/oidc/lr62/IntraVMJWTCacheProxy.java
@@ -5,104 +5,139 @@ import java.util.Comparator;
 import java.util.Map;
 import java.util.TreeMap;
 
-import javax.servlet.http.HttpSession;
-
 import org.gcube.oidc.rest.JWTToken;
 
 import com.liferay.portal.model.User;
 
 public class IntraVMJWTCacheProxy extends JWTCacheProxy {
 
-    private Map<User, Map<HttpSession, String>> oidcTokens;
-    private Map<User, Map<HttpSession, String>> rptTokens;
+    Map<User, Map<String, String>> oidcTokens;
+    Map<User, Map<String, String>> rptTokens;
+
+    private Comparator<User> userComparator = new Comparator<User>() {
+        @Override
+        public int compare(User u1, User u2) {
+            return u1.getScreenName().compareTo(u2.getScreenName());
+        }
+    };
 
     protected IntraVMJWTCacheProxy() {
+        super();
         log.info("Initializing tokens caches");
-        oidcTokens = Collections.synchronizedMap(new TreeMap<>());
-        rptTokens = Collections.synchronizedMap(new TreeMap<>());
+        oidcTokens = Collections.synchronizedMap(new TreeMap<>(userComparator));
+        rptTokens = Collections.synchronizedMap(new TreeMap<>(userComparator));
     }
 
-    public void checkMap(Map<User, Map<HttpSession, String>> map, User user) {
+    protected void checkMap(Map<User, Map<String, String>> map, User user) {
         if (!map.containsKey(user)) {
-            log.debug("Initializing map for user: " + user.getScreenName());
-            map.put(user, Collections.synchronizedMap(new TreeMap<>(new Comparator<HttpSession>() {
-                @Override
-                public int compare(HttpSession s1, HttpSession s2) {
-                    return s1.getId().compareTo(s2.getId());
-                }
-            })));
+            if (log.isDebugEnabled()) {
+                log.debug("Initializing map for user: " + user.getScreenName());
+            }
+            map.put(user, Collections.synchronizedMap(new TreeMap<>()));
         }
     }
 
     @Override
-    public void setOIDCToken(User user, HttpSession session, JWTToken token) {
+    public void setOIDCToken(User user, String sessionId, JWTToken token) {
         checkMap(oidcTokens, user);
-        Map<HttpSession, String> oidcUserMap = oidcTokens.get(user);
-        log.trace("OIDC user's sessions recorded: " + oidcUserMap.keySet().toArray());
-        oidcUserMap.put(session, JWTTokenUtil.getRawContent(token));
-    }
-
-    @Override
-    public void setUMAToken(User user, HttpSession session, JWTToken token) {
-        checkMap(rptTokens, user);
-        Map<HttpSession, String> umaUserMap = rptTokens.get(user);
-        log.trace("UMA user's sessions recorded objs: " + umaUserMap.keySet().toArray());
-        umaUserMap.put(session, JWTTokenUtil.getRawContent(token));
-    }
-
-    @Override
-    public JWTToken getOIDCToken(User user, HttpSession session) {
-        checkMap(oidcTokens, user);
-        log.trace("Getting OIDC token for user '" + user.getScreenName() + "' and session obj: " + session);
-        return JWTTokenUtil.fromString(oidcTokens.get(user).get(session));
-    }
-
-    @Override
-    public JWTToken getUMAToken(User user, HttpSession session) {
-        checkMap(rptTokens, user);
-        log.trace("Getting UMA token for user '" + user.getScreenName() + "' and session obj: " + session);
-        return JWTTokenUtil.fromString(rptTokens.get(user).get(session));
-    }
-
-    @Override
-    public void removeOIDCToken(User user, HttpSession session) {
-        checkMap(oidcTokens, user);
-        if (oidcTokens.get(user).containsKey(session)) {
-            log.trace("Removing OIDC token for user '" + user.getScreenName() + "' and session obj: " + session);
-            oidcTokens.get(user).remove(session);
+        Map<String, String> oidcUserMap = oidcTokens.get(user);
+        if (log.isTraceEnabled()) {
+            log.trace("Setting OIDC token for user '" + user.getScreenName() + "' and session: " + sessionId);
+        }
+        oidcUserMap.put(sessionId, JWTTokenUtil.getRawContent(token));
+        if (log.isTraceEnabled()) {
+            log.trace("OIDC user's sessions recorded objs: " + oidcUserMap.keySet().toArray());
         }
     }
 
     @Override
-    public void removeUMAToken(User user, HttpSession session) {
+    public void setUMAToken(User user, String sessionId, JWTToken token) {
         checkMap(rptTokens, user);
-        if (rptTokens.get(user).containsKey(session)) {
-            log.trace("Removing UMA token for user '" + user.getScreenName() + "' and session obj: " + session);
-            oidcTokens.get(user).remove(session);
+        Map<String, String> umaUserMap = rptTokens.get(user);
+        if (log.isTraceEnabled()) {
+            log.trace("Setting UMA token for user '" + user.getScreenName() + "' and session: " + sessionId);
+        }
+        umaUserMap.put(sessionId, JWTTokenUtil.getRawContent(token));
+        if (log.isTraceEnabled()) {
+            log.trace("UMA user's sessions recorded objs: " + umaUserMap.keySet().toArray());
+        }
+    }
+
+    @Override
+    public JWTToken getOIDCToken(User user, String sessionId) {
+        checkMap(oidcTokens, user);
+        if (log.isTraceEnabled()) {
+            log.trace("Getting OIDC token for user '" + user.getScreenName() + "' and session: " + sessionId);
+        }
+        return JWTTokenUtil.fromString(oidcTokens.get(user).get(sessionId));
+    }
+
+    @Override
+    public JWTToken getUMAToken(User user, String sessionId) {
+        checkMap(rptTokens, user);
+        if (log.isTraceEnabled()) {
+            log.trace("Getting UMA token for user '" + user.getScreenName() + "' and session: " + sessionId);
+        }
+        return JWTTokenUtil.fromString(rptTokens.get(user).get(sessionId));
+    }
+
+    @Override
+    public void removeOIDCToken(User user, String sessionId) {
+        checkMap(oidcTokens, user);
+        if (oidcTokens.get(user).containsKey(sessionId)) {
+            if (log.isTraceEnabled()) {
+                log.trace("Removing OIDC token for user '" + user.getScreenName() + "' and session: " + sessionId);
+            }
+            oidcTokens.get(user).remove(sessionId);
+        } else {
+            log.info("No OIDC token is stored for user '" + user.getScreenName() + "' and session: " + sessionId);
+        }
+    }
+
+    @Override
+    public void removeUMAToken(User user, String sessionId) {
+        checkMap(rptTokens, user);
+        if (rptTokens.get(user).containsKey(sessionId)) {
+            if (log.isTraceEnabled()) {
+                log.trace("Removing UMA token for user '" + user.getScreenName() + "' and session: " + sessionId);
+            }
+            oidcTokens.get(user).remove(sessionId);
+        } else {
+            if (log.isTraceEnabled()) {
+                log.debug("No UMA token is stored for user '" + user.getScreenName() + "' and session: " + sessionId);
+            }
         }
     }
 
     @Override
     public void removeAllOIDCTokens(User user) {
-        log.trace("Removing OIDC session's tokens of user: " + user.getScreenName());
+        if (log.isTraceEnabled()) {
+            log.trace("Removing all OIDC session's tokens of user: " + user.getScreenName());
+        }
         oidcTokens.remove(user);
     }
 
     @Override
     public void removeAllUMATokens(User user) {
-        log.trace("Removing UMA session's tokens of user: " + user.getScreenName());
+        if (log.isTraceEnabled()) {
+            log.trace("Removing all UMA session's tokens of user: " + user.getScreenName());
+        }
         rptTokens.remove(user);
     }
 
     @Override
     public void clearOIDCTokens() {
-        log.trace("Clearing OIDC tokens cache");
+        if (log.isTraceEnabled()) {
+            log.trace("Clearing OIDC tokens cache");
+        }
         oidcTokens.clear();
     }
 
     @Override
     public void clearUMATokens() {
-        log.trace("Clearing UMA tokens cache");
+        if (log.isTraceEnabled()) {
+            log.trace("Clearing UMA tokens cache");
+        }
         rptTokens.clear();
     }
 
@@ -112,4 +147,29 @@ public class IntraVMJWTCacheProxy extends JWTCacheProxy {
         clearUMATokens();
     }
 
+    @Override
+    public synchronized Map<String, String> getMutexFor(User user) {
+        checkMap(oidcTokens, user);
+        return oidcTokens.get(user);
+    }
+
+    @Override
+    public void dumpOnLog() {
+        if (log.isTraceEnabled()) {
+            log.trace("Cached OIDC objects: " + dumpMap(oidcTokens));
+            log.trace("Cached UMA objects: " + dumpMap(rptTokens));
+        }
+    }
+
+    protected String dumpMap(Map<User, Map<String, String>> map) {
+        StringBuffer sb = new StringBuffer();
+        map.forEach((u, v) -> {
+            sb.append(u.getScreenName() + " :");
+            v.forEach((s, t) -> {
+                sb.append(" " + s + " -> " + JWTToken.fromString(t).getTokenEssentials());
+            });
+            sb.append(", ");
+        });
+        return sb.toString();
+    }
 }
diff --git a/src/main/java/org/gcube/portal/oidc/lr62/JWTCacheProxy.java b/src/main/java/org/gcube/portal/oidc/lr62/JWTCacheProxy.java
index 3ab8ffd..4f9390c 100644
--- a/src/main/java/org/gcube/portal/oidc/lr62/JWTCacheProxy.java
+++ b/src/main/java/org/gcube/portal/oidc/lr62/JWTCacheProxy.java
@@ -1,6 +1,8 @@
 package org.gcube.portal.oidc.lr62;
 
-import javax.servlet.http.HttpSession;
+import java.util.Map;
+import java.util.Timer;
+import java.util.TimerTask;
 
 import org.gcube.oidc.rest.JWTToken;
 
@@ -16,22 +18,30 @@ public abstract class JWTCacheProxy {
 
     public JWTCacheProxy() {
         instance = this;
+        Timer timer = new Timer(true);
+        timer.scheduleAtFixedRate(new TimerTask() {
+            @Override
+            public void run() {
+                instance.dumpOnLog();
+            }
+        }, 0, 60 * 1000);
     }
+
     public static synchronized JWTCacheProxy getInstance() {
         return instance != null ? instance : new IntraVMJWTCacheProxy();
     }
 
-    public abstract void setOIDCToken(User user, HttpSession session, JWTToken token);
+    public abstract void setOIDCToken(User user, String sessionId, JWTToken token);
 
-    public abstract void setUMAToken(User user, HttpSession session, JWTToken token);
+    public abstract void setUMAToken(User user, String sessionId, JWTToken token);
 
-    public abstract JWTToken getOIDCToken(User user, HttpSession session);
+    public abstract JWTToken getOIDCToken(User user, String sessionId);
 
-    public abstract JWTToken getUMAToken(User user, HttpSession session);
+    public abstract JWTToken getUMAToken(User user, String sessionId);
 
-    public abstract void removeOIDCToken(User user, HttpSession session);
+    public abstract void removeOIDCToken(User user, String sessionId);
 
-    public abstract void removeUMAToken(User user, HttpSession session);
+    public abstract void removeUMAToken(User user, String sessionId);
 
     public abstract void removeAllOIDCTokens(User user);
 
@@ -43,4 +53,8 @@ public abstract class JWTCacheProxy {
 
     public abstract void clearAllTokens();
 
+    public abstract Map<String, String> getMutexFor(User user);
+
+    public abstract void dumpOnLog();
+
 }
\ No newline at end of file