diff --git a/ebean-datasource/src/main/java/io/ebean/datasource/pool/ConnectionPool.java b/ebean-datasource/src/main/java/io/ebean/datasource/pool/ConnectionPool.java
index 4cffbfb..59dd8c2 100644
--- a/ebean-datasource/src/main/java/io/ebean/datasource/pool/ConnectionPool.java
+++ b/ebean-datasource/src/main/java/io/ebean/datasource/pool/ConnectionPool.java
@@ -550,33 +550,16 @@ private boolean testConnection(Connection conn) throws SQLException {
     if (heartbeatsql == null) {
       return conn.isValid(heartbeatTimeoutSeconds);
     }
-    Statement stmt = null;
-    ResultSet rset = null;
-    try {
-      // It should only error IF the DataSource is down or a network issue
-      stmt = conn.createStatement();
+    // It should only error IF the DataSource is down or a network issue
+    try (Statement stmt = conn.createStatement()) {
       if (heartbeatTimeoutSeconds > 0) {
         stmt.setQueryTimeout(heartbeatTimeoutSeconds);
       }
-      rset = stmt.executeQuery(heartbeatsql);
-      conn.commit();
-
+      stmt.execute(heartbeatsql);
       return true;
-
     } finally {
-      try {
-        if (rset != null) {
-          rset.close();
-        }
-      } catch (SQLException e) {
-        log.error("Error closing resultSet", e);
-      }
-      try {
-        if (stmt != null) {
-          stmt.close();
-        }
-      } catch (SQLException e) {
-        log.error("Error closing statement", e);
+      if (!conn.getAutoCommit()) {
+        conn.rollback();
       }
     }
   }
diff --git a/ebean-datasource/src/main/java/io/ebean/datasource/pool/FreeConnectionBuffer.java b/ebean-datasource/src/main/java/io/ebean/datasource/pool/FreeConnectionBuffer.java
index 0555d10..2dd9dca 100644
--- a/ebean-datasource/src/main/java/io/ebean/datasource/pool/FreeConnectionBuffer.java
+++ b/ebean-datasource/src/main/java/io/ebean/datasource/pool/FreeConnectionBuffer.java
@@ -1,9 +1,6 @@
 package io.ebean.datasource.pool;
 
-import java.util.ArrayList;
-import java.util.Iterator;
-import java.util.LinkedList;
-import java.util.List;
+import java.util.*;
 
 /**
  * A buffer designed especially to hold free pooled connections.
@@ -64,9 +61,9 @@ void closeAll(boolean logErrors) {
   /**
    * Trim any inactive connections that have not been used since usedSince.
    */
-  int trim(long usedSince, long createdSince) {
+  int trim(int minSize, long usedSince, long createdSince) {
     int trimCount = 0;
-    Iterator<PooledConnection> iterator = freeBuffer.iterator();
+    ListIterator<PooledConnection> iterator = freeBuffer.listIterator(minSize);
     while (iterator.hasNext()) {
       PooledConnection pooledConnection = iterator.next();
       if (pooledConnection.shouldTrim(usedSince, createdSince)) {
diff --git a/ebean-datasource/src/main/java/io/ebean/datasource/pool/PooledConnectionQueue.java b/ebean-datasource/src/main/java/io/ebean/datasource/pool/PooledConnectionQueue.java
index 43b4a2d..7d7ac0e 100644
--- a/ebean-datasource/src/main/java/io/ebean/datasource/pool/PooledConnectionQueue.java
+++ b/ebean-datasource/src/main/java/io/ebean/datasource/pool/PooledConnectionQueue.java
@@ -158,7 +158,6 @@ void ensureMinimumConnections() throws SQLException {
         }
         notEmpty.signal();
       }
-
     } finally {
       lock.unlock();
     }
@@ -338,7 +337,7 @@ public void reset(long leakTimeMinutes) {
   public void trim(long maxInactiveMillis, long maxAgeMillis) {
     lock.lock();
     try {
-      if (trimInactiveConnections(maxInactiveMillis, maxAgeMillis) > 0) {
+      if (trimInactiveConnections(maxInactiveMillis, maxAgeMillis)) {
         try {
           ensureMinimumConnections();
         } catch (SQLException e) {
@@ -353,15 +352,23 @@ public void trim(long maxInactiveMillis, long maxAgeMillis) {
   /**
    * Trim connections that have been not used for some time.
    */
-  private int trimInactiveConnections(long maxInactiveMillis, long maxAgeMillis) {
-    long usedSince = System.currentTimeMillis() - maxInactiveMillis;
-    long createdSince = (maxAgeMillis == 0) ? 0 : System.currentTimeMillis() - maxAgeMillis;
-
-    int trimmedCount = freeList.trim(usedSince, createdSince);
-    if (trimmedCount > 0) {
+  private boolean trimInactiveConnections(long maxInactiveMillis, long maxAgeMillis) {
+    final long createdSince = (maxAgeMillis == 0) ? 0 : System.currentTimeMillis() - maxAgeMillis;
+    final int trimmedCount;
+    if (freeList.size() > minSize) {
+      // trim on maxInactive and maxAge
+      long usedSince = System.currentTimeMillis() - maxInactiveMillis;
+      trimmedCount = freeList.trim(minSize, usedSince, createdSince);
+    } else if (createdSince > 0) {
+      // trim only on maxAge
+      trimmedCount = freeList.trim(0, createdSince, createdSince);
+    } else {
+      trimmedCount = 0;
+    }
+    if (trimmedCount > 0 && log.isDebugEnabled()) {
       log.debug("DataSourcePool [{}] trimmed [{}] inactive connections. New size[{}]", name, trimmedCount, totalConnections());
     }
-    return trimmedCount;
+    return trimmedCount > 0 && freeList.size() < minSize;
   }
 
   /**
diff --git a/ebean-datasource/src/test/java/io/ebean/datasource/FactoryTest.java b/ebean-datasource/src/test/java/io/ebean/datasource/FactoryTest.java
index 633acf6..455e35d 100644
--- a/ebean-datasource/src/test/java/io/ebean/datasource/FactoryTest.java
+++ b/ebean-datasource/src/test/java/io/ebean/datasource/FactoryTest.java
@@ -1,9 +1,12 @@
 package io.ebean.datasource;
 
+import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
 import java.sql.Connection;
 import java.sql.PreparedStatement;
+import java.util.List;
+import java.util.ArrayList;
 
 public class FactoryTest {
 
@@ -26,6 +29,43 @@ public void createPool() throws Exception {
     }
   }
 
+  @Disabled
+  @Test
+  void readOnly2() throws Exception {
+    DataSourceConfig config = new DataSourceConfig()
+      //.setName("testReadOnly")
+      .setUrl("jdbc:h2:mem:testReadOnly3")
+      .setUsername("sa")
+      .setPassword("")
+      .setReadOnly(true)
+      .setAutoCommit(true)
+      .setHeartbeatSql("select 2")
+      .setHeartbeatFreqSecs(4)
+      .setTrimPoolFreqSecs(4)
+      .setMaxInactiveTimeSecs(4);
+
+    DataSourcePool pool = DataSourceFactory.create("testReadOnly", config);
+
+    try (Connection connection = pool.getConnection()) {
+      try (PreparedStatement stmt = connection.prepareStatement("create table junk4 (acol varchar(10))")) {
+        stmt.execute();
+        connection.commit();
+      }
+    }
+    List<Connection> connections = new ArrayList<>();
+    for (int i = 0; i < 10; i++) {
+      connections.add(pool.getConnection());
+    }
+    for (Connection connection : connections) {
+      connection.close();
+    }
+    for (int i = 0; i < 30; i++) {
+      Thread.sleep(1000);
+      System.out.println(".");
+    }
+    pool.shutdown();
+  }
+
   @Test
   public void dataSourceFactory_get_createPool() throws Exception {