diff --git a/commons-jcs-core/src/main/java/org/apache/commons/jcs/auxiliary/disk/jdbc/ShrinkerThread.java b/commons-jcs-core/src/main/java/org/apache/commons/jcs/auxiliary/disk/jdbc/ShrinkerThread.java
index 427cce6..24a9580 100644
--- a/commons-jcs-core/src/main/java/org/apache/commons/jcs/auxiliary/disk/jdbc/ShrinkerThread.java
+++ b/commons-jcs-core/src/main/java/org/apache/commons/jcs/auxiliary/disk/jdbc/ShrinkerThread.java
@@ -1,8 +1,7 @@
 package org.apache.commons.jcs.auxiliary.disk.jdbc;
 
-import java.util.Collections;
-import java.util.HashSet;
-import java.util.Set;
+import java.util.Iterator;
+import java.util.concurrent.CopyOnWriteArraySet;
 
 /*
  * Licensed to the Apache Software Foundation (ASF) under one
@@ -39,8 +38,8 @@
     private static final Log log = LogManager.getLog( ShrinkerThread.class );
 
     /** A set of JDBCDiskCache objects to call deleteExpired on. */
-    private final Set<JDBCDiskCache<?, ?>> shrinkSet =
-        Collections.synchronizedSet( new HashSet<>() );
+    private final CopyOnWriteArraySet<JDBCDiskCache<?, ?>> shrinkSet =
+            new CopyOnWriteArraySet<>();
 
     /** Default time period to use. */
     private static final long DEFAULT_PAUSE_BETWEEN_REGION_CALLS_MILLIS = 5000;
@@ -98,40 +97,29 @@
         log.info( "Running JDBC disk cache shrinker. Number of regions [{0}]",
                 () -> shrinkSet.size() );
 
-        Object[] caches = null;
-
-        synchronized ( shrinkSet )
+        for (Iterator<JDBCDiskCache<?, ?>> i = shrinkSet.iterator(); i.hasNext();)
         {
-            caches = this.shrinkSet.toArray();
-        }
+            JDBCDiskCache<?, ?> cache = i.next();
+            long start = System.currentTimeMillis();
+            int deleted = cache.deleteExpired();
+            long end = System.currentTimeMillis();
 
-        if ( caches != null )
-        {
-            for ( int i = 0; i < caches.length; i++ )
+            log.info( "Deleted [{0}] expired for region [{1}] for table [{2}] in {3} ms.",
+                    deleted, cache.getCacheName(), cache.getTableName(), end - start );
+
+            // don't pause after the last call to delete expired.
+            if ( i.hasNext() )
             {
-                JDBCDiskCache<?, ?> cache = (JDBCDiskCache<?, ?>) caches[i];
+                log.info( "Pausing for [{0}] ms before shrinking the next region.",
+                        this.getPauseBetweenRegionCallsMillis() );
 
-                long start = System.currentTimeMillis();
-                int deleted = cache.deleteExpired();
-                long end = System.currentTimeMillis();
-
-                log.info( "Deleted [{0}] expired for region [{1}] for table [{2}] in {3} ms.",
-                        deleted, cache.getCacheName(), cache.getTableName(), end - start );
-
-                // don't pause after the last call to delete expired.
-                if ( i < caches.length - 1 )
+                try
                 {
-                    log.info( "Pausing for [{0}] ms before shrinking the next region.",
-                            this.getPauseBetweenRegionCallsMillis() );
-
-                    try
-                    {
-                        Thread.sleep( this.getPauseBetweenRegionCallsMillis() );
-                    }
-                    catch ( InterruptedException e )
-                    {
-                        log.warn( "Interrupted while waiting to delete expired for the next region." );
-                    }
+                    Thread.sleep( this.getPauseBetweenRegionCallsMillis() );
+                }
+                catch ( InterruptedException e )
+                {
+                    log.warn( "Interrupted while waiting to delete expired for the next region." );
                 }
             }
         }
diff --git a/commons-jcs-core/src/main/java/org/apache/commons/jcs/auxiliary/disk/jdbc/hsql/HSQLDiskCacheFactory.java b/commons-jcs-core/src/main/java/org/apache/commons/jcs/auxiliary/disk/jdbc/hsql/HSQLDiskCacheFactory.java
index e2e964d..186e46b 100644
--- a/commons-jcs-core/src/main/java/org/apache/commons/jcs/auxiliary/disk/jdbc/hsql/HSQLDiskCacheFactory.java
+++ b/commons-jcs-core/src/main/java/org/apache/commons/jcs/auxiliary/disk/jdbc/hsql/HSQLDiskCacheFactory.java
@@ -23,9 +23,7 @@
 import java.sql.DriverManager;
 import java.sql.SQLException;
 import java.sql.Statement;
-import java.util.Collections;
-import java.util.HashSet;
-import java.util.Set;
+import java.util.concurrent.CopyOnWriteArraySet;
 
 import org.apache.commons.jcs.auxiliary.AuxiliaryCacheAttributes;
 import org.apache.commons.jcs.auxiliary.disk.jdbc.JDBCDiskCache;
@@ -49,7 +47,7 @@
     private static final Log log = LogManager.getLog( HSQLDiskCacheFactory.class );
 
     /** The databases. */
-    private Set<String> databases;
+    private CopyOnWriteArraySet<String> databases;
 
     /**
      * This factory method should create an instance of the hsqlcache.
@@ -79,7 +77,7 @@
     public void initialize()
     {
         super.initialize();
-        this.databases = Collections.synchronizedSet( new HashSet<>() );
+        this.databases = new CopyOnWriteArraySet<>();
     }
 
     /**
@@ -105,31 +103,34 @@
             return;
         }
 
-        // TODO get this from the attributes.
-        System.setProperty( "hsqldb.cache_scale", "8" );
-
-        // "org.hsqldb.jdbcDriver"
-        String driver = attributes.getDriverClassName();
-        // "sa"
-        String user = attributes.getUserName();
-        // ""
-        String password = attributes.getPassword();
-
-        try
+        synchronized (databases)
         {
-            Class.forName( driver ).newInstance();
+            // TODO get this from the attributes.
+            System.setProperty( "hsqldb.cache_scale", "8" );
+
+            // "org.hsqldb.jdbcDriver"
+            String driver = attributes.getDriverClassName();
+            // "sa"
+            String user = attributes.getUserName();
+            // ""
+            String password = attributes.getPassword();
+
+            try
+            {
+                Class.forName( driver ).newInstance();
+            }
+            catch (Exception e)
+            {
+                throw new SQLException( "Could not initialize driver " + driver, e );
+            }
+
+            Connection cConn = DriverManager.getConnection( database, user, password );
+            setupTable( cConn, attributes.getTableName() );
+
+            log.info( "Finished setting up database [{0}]", database);
+
+            databases.add( database );
         }
-        catch (Exception e)
-        {
-            throw new SQLException( "Could not initialize driver " + driver, e );
-        }
-
-        Connection cConn = DriverManager.getConnection( database, user, password );
-        setupTable( cConn, attributes.getTableName() );
-
-        log.info( "Finished setting up database [{0}]", database);
-
-        databases.add( database );
     }
 
     /**
diff --git a/commons-jcs-core/src/main/java/org/apache/commons/jcs/auxiliary/lateral/socket/tcp/LateralTCPDiscoveryListener.java b/commons-jcs-core/src/main/java/org/apache/commons/jcs/auxiliary/lateral/socket/tcp/LateralTCPDiscoveryListener.java
index 94d37d8..6816ab2 100644
--- a/commons-jcs-core/src/main/java/org/apache/commons/jcs/auxiliary/lateral/socket/tcp/LateralTCPDiscoveryListener.java
+++ b/commons-jcs-core/src/main/java/org/apache/commons/jcs/auxiliary/lateral/socket/tcp/LateralTCPDiscoveryListener.java
@@ -1,11 +1,9 @@
 package org.apache.commons.jcs.auxiliary.lateral.socket.tcp;
 
 import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.Map;
-import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 /*
  * Licensed to the Apache Software Foundation (ASF) under one
@@ -53,15 +51,15 @@
      * Map of no wait facades. these are used to determine which regions are locally configured to
      * use laterals.
      */
-    private final Map<String, LateralCacheNoWaitFacade<?, ?>> facades =
-        Collections.synchronizedMap( new HashMap<>() );
+    private final ConcurrentMap<String, LateralCacheNoWaitFacade<?, ?>> facades =
+        new ConcurrentHashMap<>();
 
     /**
      * List of regions that are configured differently here than on another server. We keep track of
      * this to limit the amount of info logging.
      */
-    private final Set<String> knownDifferentlyConfiguredRegions =
-        Collections.synchronizedSet( new HashSet<>() );
+    private final CopyOnWriteArrayList<String> knownDifferentlyConfiguredRegions =
+        new CopyOnWriteArrayList<>();
 
     /** The name of the cache factory */
     private String factoryName;
@@ -91,7 +89,7 @@
      * @param facade - facade (for region) =&gt; multiple lateral clients.
      * @return true if the facade was not already registered.
      */
-    public synchronized boolean addNoWaitFacade( String cacheName, LateralCacheNoWaitFacade<?, ?> facade )
+    public boolean addNoWaitFacade( String cacheName, LateralCacheNoWaitFacade<?, ?> facade )
     {
         boolean isNew = !containsNoWaitFacade( cacheName );
 
@@ -123,7 +121,9 @@
     public <K, V> boolean containsNoWait( String cacheName, LateralCacheNoWait<K, V> noWait )
     {
         @SuppressWarnings("unchecked") // Need to cast because of common map for all facades
-        LateralCacheNoWaitFacade<K, V> facade = (LateralCacheNoWaitFacade<K, V>)facades.get( noWait.getCacheName() );
+        LateralCacheNoWaitFacade<K, V> facade =
+            (LateralCacheNoWaitFacade<K, V>)facades.get( noWait.getCacheName() );
+
         if ( facade == null )
         {
             return false;
@@ -141,13 +141,14 @@
      * services.
      * <p>
      * @param noWait
-     * @return true if we found the no wait and added it. False if the no wait was not present or it
+     * @return true if we found the no wait and added it. False if the no wait was not present or if
      *         we already had it.
      */
     protected <K, V> boolean addNoWait( LateralCacheNoWait<K, V> noWait )
     {
         @SuppressWarnings("unchecked") // Need to cast because of common map for all facades
-        LateralCacheNoWaitFacade<K, V> facade = (LateralCacheNoWaitFacade<K, V>)facades.get( noWait.getCacheName() );
+        LateralCacheNoWaitFacade<K, V> facade =
+            (LateralCacheNoWaitFacade<K, V>)facades.get( noWait.getCacheName() );
         log.debug( "addNoWait > Got facade for {0} = {1}", noWait.getCacheName(), facade );
 
         if ( facade != null )
@@ -158,12 +159,11 @@
         }
         else
         {
-            if ( !knownDifferentlyConfiguredRegions.contains( noWait.getCacheName() ) )
+            if ( knownDifferentlyConfiguredRegions.addIfAbsent( noWait.getCacheName() ) )
             {
                 log.info( "addNoWait > Different nodes are configured differently "
                         + "or region [{0}] is not yet used on this side.",
                         () -> noWait.getCacheName() );
-                knownDifferentlyConfiguredRegions.add( noWait.getCacheName() );
             }
             return false;
         }
@@ -179,7 +179,8 @@
     protected <K, V> boolean removeNoWait( LateralCacheNoWait<K, V> noWait )
     {
         @SuppressWarnings("unchecked") // Need to cast because of common map for all facades
-        LateralCacheNoWaitFacade<K, V> facade = (LateralCacheNoWaitFacade<K, V>)facades.get( noWait.getCacheName() );
+        LateralCacheNoWaitFacade<K, V> facade =
+            (LateralCacheNoWaitFacade<K, V>)facades.get( noWait.getCacheName() );
         log.debug( "removeNoWait > Got facade for {0} = {1}", noWait.getCacheName(), facade);
 
         if ( facade != null )
@@ -190,12 +191,11 @@
         }
         else
         {
-            if ( !knownDifferentlyConfiguredRegions.contains( noWait.getCacheName() ) )
+            if ( knownDifferentlyConfiguredRegions.addIfAbsent( noWait.getCacheName() ) )
             {
-                log.info( "removeNoWait > Different nodes are configured differently "
+                log.info( "addNoWait > Different nodes are configured differently "
                         + "or region [{0}] is not yet used on this side.",
                         () -> noWait.getCacheName() );
-                knownDifferentlyConfiguredRegions.add( noWait.getCacheName() );
             }
             return false;
         }
diff --git a/commons-jcs-core/src/test/java/org/apache/commons/jcs/JCSConcurrentCacheAccessUnitTest.java b/commons-jcs-core/src/test/java/org/apache/commons/jcs/JCSConcurrentCacheAccessUnitTest.java
index 0775fc0..48932cb 100644
--- a/commons-jcs-core/src/test/java/org/apache/commons/jcs/JCSConcurrentCacheAccessUnitTest.java
+++ b/commons-jcs-core/src/test/java/org/apache/commons/jcs/JCSConcurrentCacheAccessUnitTest.java
@@ -19,16 +19,15 @@
  * under the License.
  */
 
-import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.atomic.AtomicInteger;
 
-import junit.framework.TestCase;
-
 import org.apache.commons.jcs.access.GroupCacheAccess;
 import org.apache.commons.jcs.access.exception.CacheException;
 
+import junit.framework.TestCase;
+
 /**
  * Test Case for JCS-73, modeled after the Groovy code by Alexander Kleymenov
  *
@@ -67,7 +66,7 @@
         JCS.setConfigFilename( "/TestJCS-73.ccf" );
         cache = JCS.getGroupCacheInstance( "cache" );
         errcount = new AtomicInteger(0);
-        valueMismatchList = Collections.synchronizedList(new ArrayList<>());
+        valueMismatchList = new CopyOnWriteArrayList<>();
 	}
 
     @Override