chore: apply 2.6.x latest changes

CHANGELOG.md

@@ -25,6 +25,17 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ### :magic_wand: Added
 - Added support of Global Databases including and Global Database endpoint. ([PR #1573](https://github.com/aws/aws-advanced-jdbc-wrapper/pull/1573)).
+
+## [2.6.8] - 2025-12-04
+
+### :bug: Fixed
+- Wait timeout for custom endpoint info ([PR #1616](https://github.com/aws/aws-advanced-jdbc-wrapper/pull/1616)) 
+- Use custom endpoint as cluster ID to prevent accumulating of connections if using a custom endpoint in a connection string ([PR #1619](https://github.com/aws/aws-advanced-jdbc-wrapper/pull/1619))
+
+### :crab: Changed
+- Improve exception handling when DB server reaches maximum available connections ([PR #1621](https://github.com/aws/aws-advanced-jdbc-wrapper/pull/1621))
+- Improve connection management to prevent connection leaking in topology monitor ([PR #1624](https://github.com/aws/aws-advanced-jdbc-wrapper/pull/1624))
+
 ## [2.6.7] - 2025-11-25
 
 ### :bug: Fixed
@@ -582,6 +593,9 @@ The Amazon Web Services (AWS) Advanced JDBC Driver allows an application to take
 - The [AWS IAM Authentication Connection Plugin](./docs/using-the-jdbc-driver/using-plugins/UsingTheIamAuthenticationPlugin.md)
 - The [AWS Secrets Manager Connection Plugin](./docs/using-the-jdbc-driver/using-plugins/UsingTheAwsSecretsManagerPlugin.md)
 
+[2.6.8]: https://github.com/aws/aws-advanced-jdbc-wrapper/compare/2.6.7...2.6.8
+[2.6.7]: https://github.com/aws/aws-advanced-jdbc-wrapper/compare/2.6.6...2.6.7
+[2.6.6]: https://github.com/aws/aws-advanced-jdbc-wrapper/compare/2.6.5...2.6.6
 [2.6.5]: https://github.com/aws/aws-advanced-jdbc-wrapper/compare/2.6.4...2.6.5
 [2.6.4]: https://github.com/aws/aws-advanced-jdbc-wrapper/compare/2.6.3...2.6.4
 [2.6.3]: https://github.com/aws/aws-advanced-jdbc-wrapper/compare/2.6.2...2.6.3

Maintenance.md

@@ -40,6 +40,7 @@
 | October 16, 2025   | [Release 2.6.5](https://github.com/aws/aws-advanced-jdbc-wrapper/releases/tag/2.6.5) |
 | November 5, 2025   | [Release 2.6.6](https://github.com/aws/aws-advanced-jdbc-wrapper/releases/tag/2.6.6) |
 | November 25, 2025  | [Release 2.6.7](https://github.com/aws/aws-advanced-jdbc-wrapper/releases/tag/2.6.7) |
+| December 4, 2025   | [Release 2.6.8](https://github.com/aws/aws-advanced-jdbc-wrapper/releases/tag/2.6.8) |
 
 `aws-advanced-jdbc-wrapper` [follows semver](https://semver.org/#semantic-versioning-200) which means we will only
 release breaking changes in major versions. Generally speaking patches will be released to fix existing problems without
@@ -93,5 +94,5 @@ from the updated source after the PRs are merged.
 | Major Version | Latest Minor Version | Status      | Initial Release | Maintenance Window Start | Maintenance Window End |
 |---------------|----------------------|-------------|-----------------|--------------------------|------------------------|
 | 1             | 1.0.2                | Maintenance | Oct 5, 2022     | Apr 28, 2023             | Apr 28, 2024           | 
-| 2             | 2.6.7                | Maintenance | Jan 1, 2026     | Dec 31, 2026             | N/A                    | 
+| 2             | 2.6.8                | Maintenance | Apr 28, 2023    | Dec 31, 2026             | N/A                    | 
 | 3             | 3.0.0                | Current     | Dec 12, 2025    | N/A                      | N/A                    | 

wrapper/src/main/java/software/amazon/jdbc/exceptions/MySQLExceptionHandler.java

@@ -73,7 +73,8 @@ public boolean isNetworkException(final String sqlState) {
       return false;
     }
 
-    return sqlState.startsWith("08");
+    // 08004 -  "Server rejected the connection" or "Connection refused by server"
+    return sqlState.startsWith("08") && !"08004".equals(sqlState);
   }
 
   @Override

wrapper/src/main/java/software/amazon/jdbc/exceptions/PgExceptionHandler.java

@@ -23,7 +23,6 @@ public class PgExceptionHandler extends AbstractPgExceptionHandler {
 
   // The following SQL States for Postgresql are considered as "communication" errors
   private static final List<String> NETWORK_ERRORS = Arrays.asList(
-      "53", // insufficient resources
       "57P01", // admin shutdown
       "57P02", // crash shutdown
       "57P03", // cannot connect now

wrapper/src/main/java/software/amazon/jdbc/hostlistprovider/GlobalAuroraTopologyUtils.java

@@ -55,7 +55,9 @@ public GlobalAuroraTopologyUtils(GlobalAuroraTopologyDialect dialect, HostSpecBu
   public @Nullable List<HostSpec> queryForTopology(
       Connection conn, HostSpec initialHostSpec, Map<String, HostSpec> instanceTemplatesByRegion)
       throws SQLException {
-    int originalNetworkTimeout = setNetworkTimeout(conn);
+    final Pair<Integer, Boolean> networkTimeoutPair = this.setNetworkTimeout(conn);
+    int originalNetworkTimeout = networkTimeoutPair.getValue1();
+    boolean timeoutChanged = networkTimeoutPair.getValue2();
     try (final Statement stmt = conn.createStatement();
          final ResultSet rs = stmt.executeQuery(this.dialect.getTopologyQuery())) {
       if (rs.getMetaData().getColumnCount() == 0) {
@@ -68,7 +70,7 @@ public GlobalAuroraTopologyUtils(GlobalAuroraTopologyDialect dialect, HostSpecBu
     } catch (final SQLSyntaxErrorException e) {
       throw new SQLException(Messages.get("TopologyUtils.invalidQuery"), e);
     } finally {
-      if (originalNetworkTimeout == 0 && !conn.isClosed()) {
+      if (timeoutChanged && !conn.isClosed()) {
         conn.setNetworkTimeout(networkTimeoutExecutor, originalNetworkTimeout);
       }
     }

wrapper/src/main/java/software/amazon/jdbc/hostlistprovider/TopologyUtils.java

@@ -71,7 +71,9 @@ public TopologyUtils(
    */
   public @Nullable List<HostSpec> queryForTopology(Connection conn, HostSpec initialHostSpec, HostSpec instanceTemplate)
       throws SQLException {
-    int originalNetworkTimeout = setNetworkTimeout(conn);
+    final Pair<Integer, Boolean> networkTimeoutPair = this.setNetworkTimeout(conn);
+    int originalNetworkTimeout = networkTimeoutPair.getValue1();
+    boolean timeoutChanged = networkTimeoutPair.getValue2();
     try (final Statement stmt = conn.createStatement();
          final ResultSet rs = stmt.executeQuery(this.dialect.getTopologyQuery())) {
       if (rs.getMetaData().getColumnCount() == 0) {
@@ -84,24 +86,26 @@ public TopologyUtils(
     } catch (final SQLSyntaxErrorException e) {
       throw new SQLException(Messages.get("TopologyUtils.invalidQuery"), e);
     } finally {
-      if (originalNetworkTimeout == 0 && !conn.isClosed()) {
+      if (timeoutChanged && !conn.isClosed()) {
         conn.setNetworkTimeout(networkTimeoutExecutor, originalNetworkTimeout);
       }
     }
   }
 
-  protected int setNetworkTimeout(Connection conn) {
+  protected Pair<Integer, Boolean> setNetworkTimeout(Connection conn) {
     int networkTimeout = -1;
+    boolean timeoutChanged = false;
     try {
       networkTimeout = conn.getNetworkTimeout();
       // The topology query is not monitored by the EFM plugin, so it needs a socket timeout.
       if (networkTimeout == 0) {
         conn.setNetworkTimeout(this.networkTimeoutExecutor, DEFAULT_QUERY_TIMEOUT_MS);
+        timeoutChanged = true;
       }
     } catch (SQLException e) {
       LOGGER.warning(() -> Messages.get("TopologyUtils.errorGettingNetworkTimeout", new Object[] {e.getMessage()}));
     }
-    return networkTimeout;
+    return Pair.create(networkTimeout, timeoutChanged);
   }
 
   protected abstract @Nullable List<HostSpec> getHosts(

wrapper/src/main/java/software/amazon/jdbc/hostlistprovider/monitoring/ClusterTopologyMonitorImpl.java

@@ -21,10 +21,9 @@
 import java.sql.SQLSyntaxErrorException;
 import java.util.ArrayList;
 import java.util.Collections;
-import java.util.Comparator;
-import java.util.HashMap;
 import java.util.List;
 import java.util.Properties;
+import java.util.Random;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.Executor;
 import java.util.concurrent.ExecutorService;
@@ -73,6 +72,10 @@ public class ClusterTopologyMonitorImpl extends AbstractMonitor implements Clust
   protected static final long highRefreshPeriodAfterPanicNano = TimeUnit.SECONDS.toNanos(30);
   protected static final long ignoreTopologyRequestNano = TimeUnit.SECONDS.toNanos(10);
 
+  private static final long INITIAL_BACKOFF_MS = 100;
+  private static final long MAX_BACKOFF_MS = 10000;
+  private static final Random random = new Random();
+
   protected final AtomicReference<HostSpec> writerHostSpec = new AtomicReference<>(null);
   protected final AtomicReference<Connection> monitoringConnection = new AtomicReference<>(null);
 
@@ -237,7 +240,11 @@ private List<HostSpec> getStoredHosts() {
   @Override
   public void stop() {
     this.nodeThreadsStop.set(true);
-    this.shutdownNodeExecutorService();
+
+    this.closeNodeMonitors();
+    this.closeConnection(this.nodeThreadsWriterConnection);
+    this.closeConnection(this.nodeThreadsReaderConnection);
+    this.closeConnection(this.monitoringConnection);
 
     // This code interrupts the waiting/sleeping cycle in the monitoring thread.
     synchronized (this.requestToUpdateTopology) {
@@ -250,6 +257,7 @@ public void stop() {
 
   @Override
   public void close() {
+    this.closeNodeMonitors();
     this.closeConnection(this.monitoringConnection);
     this.closeConnection(this.nodeThreadsWriterConnection);
     this.closeConnection(this.nodeThreadsReaderConnection);
@@ -277,8 +285,7 @@ public void monitor() throws Exception {
 
             // Start node monitors.
             this.nodeThreadsStop.set(false);
-            this.nodeThreadsWriterConnection.set(null);
-            this.nodeThreadsReaderConnection.set(null);
+            this.nodeThreadConnectionCleanUp();
             this.nodeThreadsWriterHostSpec.set(null);
             this.nodeThreadsLatestTopology.set(null);
 
@@ -288,7 +295,7 @@ public void monitor() throws Exception {
               hosts = this.openAnyConnectionAndUpdateTopology();
             }
 
-            this.shutdownNodeExecutorService();
+            this.closeNodeMonitors();
             this.createNodeExecutorService();
 
             if (hosts != null && !this.isVerifiedWriterConnection) {
@@ -341,7 +348,7 @@ public void monitor() throws Exception {
               }
 
               this.nodeThreadsStop.set(true);
-              this.shutdownNodeExecutorService();
+              this.closeNodeMonitors();
               this.submittedNodes.clear();
 
               continue;
@@ -381,7 +388,7 @@ public void monitor() throws Exception {
         } else {
           // We are in regular mode (not panic mode).
           if (!this.submittedNodes.isEmpty()) {
-            this.shutdownNodeExecutorService();
+            this.closeNodeMonitors();
             this.submittedNodes.clear();
           }
 
@@ -390,6 +397,7 @@ public void monitor() throws Exception {
             // Attempt to fetch topology failed, so we switch to panic mode.
             this.closeConnection(this.monitoringConnection);
             this.isVerifiedWriterConnection = false;
+            this.writerHostSpec.set(null);
             continue;
           }
 
@@ -428,11 +436,9 @@ public void monitor() throws Exception {
       throw ex;
     } finally {
       this.stop.set(true);
-      this.shutdownNodeExecutorService();
-
-      final Connection conn = this.monitoringConnection.get();
-      this.monitoringConnection.set(null);
-      this.closeConnection(conn);
+      this.closeNodeMonitors();
+      this.closeConnection(this.monitoringConnection);
+      this.nodeThreadConnectionCleanUp();
 
       this.servicesContainer.getEventPublisher().unsubscribe(
           this, Collections.singleton(MonitorResetEvent.class));
@@ -448,14 +454,13 @@ protected void reset() {
             new Object[]{this.clusterId, this.initialHostSpec.getHost()}));
 
     this.nodeThreadsStop.set(true);
-    this.shutdownNodeExecutorService();
+    this.closeNodeMonitors();
+    this.nodeThreadConnectionCleanUp();
     this.nodeThreadsStop.set(false);
     this.submittedNodes.clear();
     this.createNodeExecutorService();
 
-    this.nodeThreadsWriterConnection.set(null);
     this.nodeThreadsWriterHostSpec.set(null);
-    this.nodeThreadsReaderConnection.set(null);
     this.nodeThreadsLatestTopology.set(null);
 
     this.closeConnection(this.monitoringConnection);
@@ -484,7 +489,20 @@ public void processEvent(Event event) {
     }
   }
 
-  protected void shutdownNodeExecutorService() {
+  protected void nodeThreadConnectionCleanUp() {
+    if (this.monitoringConnection.get() != this.nodeThreadsWriterConnection.get()) {
+      this.closeConnection(this.nodeThreadsWriterConnection);
+    } else {
+      this.nodeThreadsWriterConnection.set(null);
+    }
+    if (this.monitoringConnection.get() != this.nodeThreadsReaderConnection.get()) {
+      this.closeConnection(this.nodeThreadsReaderConnection);
+    } else {
+      this.nodeThreadsReaderConnection.set(null);
+    }
+  }
+
+  protected void closeNodeMonitors() {
     if (this.nodeExecutorService != null) {
 
       this.nodeExecutorLock.lock();
@@ -507,6 +525,8 @@ protected void shutdownNodeExecutorService() {
         }
 
         this.nodeExecutorService = null;
+        this.nodeThreadConnectionCleanUp();
+
       } finally {
         this.nodeExecutorLock.unlock();
       }
@@ -600,6 +620,7 @@ protected List<HostSpec> openAnyConnectionAndUpdateTopology() {
       // Attempt to fetch topology failed. There might be something wrong with the connection, so we close it here.
       this.closeConnection(this.monitoringConnection);
       this.isVerifiedWriterConnection = false;
+      this.writerHostSpec.set(null);
     }
 
     return hosts;
@@ -702,6 +723,7 @@ private static class NodeMonitoringWorker implements Runnable {
     protected final HostSpec hostSpec;
     protected final @Nullable HostSpec writerHostSpec;
     protected boolean writerChanged = false;
+    protected int connectionAttempts = 0;
 
     public NodeMonitoringWorker(
         final FullServicesContainer servicesContainer,
@@ -729,10 +751,25 @@ public void run() {
             try {
               connection = this.servicesContainer.getPluginService().forceConnect(
                   hostSpec, this.monitor.monitoringProperties);
+              this.connectionAttempts = 0;
             } catch (SQLException ex) {
-              // A problem occurred while connecting. We will try again on the next iteration.
-              TimeUnit.MILLISECONDS.sleep(100);
-              continue;
+              // A problem occurred while connecting.
+              if (this.servicesContainer.getPluginService().isNetworkException(
+                  ex, this.servicesContainer.getPluginService().getTargetDriverDialect())) {
+                // It's a network issue that's expected during a cluster failover.
+                // We will try again on the next iteration.
+                TimeUnit.MILLISECONDS.sleep(100);
+                continue;
+              } else if (this.servicesContainer.getPluginService().isLoginException(
+                    ex, this.servicesContainer.getPluginService().getTargetDriverDialect())) {
+                // Something wrong with login credentials. We can't continue.
+                throw new RuntimeException(ex);
+              } else {
+                // It might be some transient error. Let's try again.
+                //  If the error repeats, we will try again after a longer delay.
+                TimeUnit.MILLISECONDS.sleep(this.calculateBackoffWithJitter(this.connectionAttempts++));
+                continue;
+              }
             }
           }
 
@@ -790,12 +827,10 @@ public void run() {
                 // be established.
                 if (updateTopology) {
                   this.readerThreadFetchTopology(connection, this.writerHostSpec);
-                } else if (this.monitor.nodeThreadsReaderConnection.get() == null) {
-                  if (this.monitor.nodeThreadsReaderConnection.compareAndSet(null, connection)) {
-                    // Use this connection to update the topology.
-                    updateTopology = true;
-                    this.readerThreadFetchTopology(connection, this.writerHostSpec);
-                  }
+                } else if (this.monitor.nodeThreadsReaderConnection.compareAndSet(null, connection)) {
+                  // Use this connection to update the topology.
+                  updateTopology = true;
+                  this.readerThreadFetchTopology(connection, this.writerHostSpec);
                 }
               }
             }
@@ -858,5 +893,11 @@ private void readerThreadFetchTopology(final Connection connection, final @Nulla
         LOGGER.fine(() -> LogUtils.logTopology(hosts));
       }
     }
+
+    private long calculateBackoffWithJitter(int attempt) {
+      long backoff = INITIAL_BACKOFF_MS * Math.round(Math.pow(2, Math.min(attempt, 6)));
+      backoff = Math.min(backoff, MAX_BACKOFF_MS);
+      return Math.round(backoff * (0.5 + random.nextDouble() * 0.5));
+    }
   }
 }