fix issue #3524

Author: guanchengang

src/main/java/org/apache/ibatis/datasource/pooled/PooledDataSource.java

@@ -1,5 +1,5 @@
 /*
- *    Copyright 2009-2024 the original author or authors.
+ *    Copyright 2009-2025 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -389,11 +389,10 @@ private int assembleConnectionTypeCode(String url, String username, String passw
   }
 
   protected void pushConnection(PooledConnection conn) throws SQLException {
-
     lock.lock();
     try {
-      state.activeConnections.remove(conn);
       if (conn.isValid()) {
+        state.activeConnections.remove(conn);
         if (state.idleConnections.size() < poolMaximumIdleConnections
             && conn.getConnectionTypeCode() == expectedConnectionTypeCode) {
           state.accumulatedCheckoutTime += conn.getCheckoutTime();
@@ -441,17 +440,19 @@ private PooledConnection popConnection(String username, String password) throws
     while (conn == null) {
       lock.lock();
       try {
-        if (!state.idleConnections.isEmpty()) {
-          // Pool has available connection
-          conn = state.idleConnections.remove(0);
-          if (log.isDebugEnabled()) {
-            log.debug("Checked out connection " + conn.getRealHashCode() + " from pool.");
-          }
-        } else if (state.activeConnections.size() < poolMaximumActiveConnections) {
-          // Pool does not have available connection and can create a new connection
-          conn = new PooledConnection(dataSource.getConnection(), this);
-          if (log.isDebugEnabled()) {
-            log.debug("Created connection " + conn.getRealHashCode() + ".");
+        if (state.activeConnections.size() < poolMaximumActiveConnections) {
+          if (!state.idleConnections.isEmpty()) {
+            // Pool has available connection
+            conn = state.idleConnections.remove(0);
+            if (log.isDebugEnabled()) {
+              log.debug("Checked out connection " + conn.getRealHashCode() + " from pool.");
+            }
+          } else {
+            // Pool does not have available connection and can create a new connection
+            conn = new PooledConnection(dataSource.getConnection(), this);
+            if (log.isDebugEnabled()) {
+              log.debug("Created connection " + conn.getRealHashCode() + ".");
+            }
           }
         } else {
           // Cannot create new connection

src/test/java/org/apache/ibatis/datasource/pooled/PooledDataSourceTest.java

@@ -1,5 +1,5 @@
 /*
- *    Copyright 2009-2023 the original author or authors.
+ *    Copyright 2009-2025 the original author or authors.
  *
  *    Licensed under the Apache License, Version 2.0 (the "License");
  *    you may not use this file except in compliance with the License.
@@ -158,4 +158,27 @@ void forceCloseAllShouldRemoveAllActiveAndIdleConnection() throws SQLException {
     assertEquals(0, poolState.getActiveConnectionCount());
     assertEquals(0, poolState.getIdleConnectionCount());
   }
+
+  @Test
+  void shouldActiveConnectionLessThanOrEqualPoolMaximumActiveConnections() throws Exception {
+    dataSource.setPoolMaximumCheckoutTime(1000);
+    dataSource.setPoolTimeToWait(500);
+    dataSource.setPoolMaximumActiveConnections(1);
+    dataSource.setPoolMaximumIdleConnections(1);
+
+    Connection conn1 = dataSource.getConnection();
+    conn1.setAutoCommit(false);
+    Connection conn2 = dataSource.getConnection();
+    conn2.setAutoCommit(false);
+    conn1.close();
+    Connection conn3 = dataSource.getConnection();
+    conn3.setAutoCommit(false);
+    conn2.close();
+    Connection conn4 = dataSource.getConnection();
+    conn4.setAutoCommit(false);
+    PoolState poolState = dataSource.getPoolState();
+    assertTrue(poolState.activeConnections.size() <= poolState.dataSource.poolMaximumActiveConnections);
+    conn3.close();
+    conn4.close();
+  }
 }