diff --git a/src/main/java/org/redkale/source/AbstractDataSqlSource.java b/src/main/java/org/redkale/source/AbstractDataSqlSource.java
index b18e92c13..51f53682e 100644
--- a/src/main/java/org/redkale/source/AbstractDataSqlSource.java
+++ b/src/main/java/org/redkale/source/AbstractDataSqlSource.java
@@ -300,7 +300,7 @@ public abstract class AbstractDataSqlSource extends AbstractDataSource implement
             if (pos > 0) {
                 url = url.substring(0, pos) + "...";
             }
-            return getClass().getSimpleName() + "{url=" + url + "}";
+            return getClass().getSimpleName() + "{url=" + url + ", maxconns=" + readMaxConns() + "}";
         } else {
             String readUrl = readConfProps.getProperty(DATA_SOURCE_URL);
             int pos = readUrl.indexOf('?');
@@ -312,10 +312,14 @@ public abstract class AbstractDataSqlSource extends AbstractDataSource implement
             if (pos > 0) {
                 writeUrl = writeUrl.substring(0, pos) + "...";
             }
-            return getClass().getSimpleName() + "{readurl=" + readUrl + ",writeurl=" + writeUrl + "}";
+            return getClass().getSimpleName() + "{read-url=" + readUrl + ", read-maxconns=" + readMaxConns() + ",write-url=" + writeUrl + ", write-maxconns=" + writeMaxConns() + "}";
         }
     }
 
+    protected abstract int readMaxConns();
+
+    protected abstract int writeMaxConns();
+
     //生成创建表的SQL
     protected <T> String[] createTableSqls(EntityInfo<T> info) {
         if (info == null || !autoDDL) {
diff --git a/src/main/java/org/redkale/source/DataJdbcSource.java b/src/main/java/org/redkale/source/DataJdbcSource.java
index 2fd0b37a3..5883bb470 100644
--- a/src/main/java/org/redkale/source/DataJdbcSource.java
+++ b/src/main/java/org/redkale/source/DataJdbcSource.java
@@ -67,6 +67,16 @@ public class DataJdbcSource extends AbstractDataSqlSource {
         this.writePool.onResourceChange(events);
     }
 
+    @Override
+    protected int readMaxConns() {
+        return this.readPool.maxConns;
+    }
+
+    @Override
+    protected int writeMaxConns() {
+        return this.writePool.maxConns;
+    }
+
     @Override
     public void destroy(AnyValue config) {
         if (readPool != null) {
@@ -2694,8 +2704,6 @@ public class DataJdbcSource extends AbstractDataSqlSource {
 
         protected final LongAdder cycleCounter = new LongAdder(); //已复用连接数
 
-        protected final LongAdder waitingCounter = new LongAdder(); //可用中连接数
-
         protected final java.sql.Driver driver;
 
         protected final Properties connectAttrs;
@@ -2706,6 +2714,8 @@ public class DataJdbcSource extends AbstractDataSqlSource {
 
         protected int maxConns;
 
+        protected Semaphore canNewSemaphore;
+
         protected String url;
 
         protected int urlVersion;
@@ -2713,7 +2723,7 @@ public class DataJdbcSource extends AbstractDataSqlSource {
         protected Properties clientInfo = new Properties();
 
         public ConnectionPool(Properties prop) {
-            this.connectTimeoutSeconds = Integer.decode(prop.getProperty(DATA_SOURCE_CONNECTTIMEOUT_SECONDS, "6"));
+            this.connectTimeoutSeconds = Integer.decode(prop.getProperty(DATA_SOURCE_CONNECTTIMEOUT_SECONDS, "30"));
             int defMaxConns = Utility.cpus() * 4;
             if (workExecutor instanceof ThreadPoolExecutor) {
                 defMaxConns = ((ThreadPoolExecutor) workExecutor).getCorePoolSize();
@@ -2723,6 +2733,7 @@ public class DataJdbcSource extends AbstractDataSqlSource {
                 defMaxConns = Math.min(1000, Utility.cpus() * 100);
             }
             this.maxConns = Math.max(1, Integer.decode(prop.getProperty(DATA_SOURCE_MAXCONNS, "" + defMaxConns)));
+            this.canNewSemaphore = new Semaphore(this.maxConns);
             this.queue = new ArrayBlockingQueue<>(maxConns);
             this.url = prop.getProperty(DATA_SOURCE_URL);
             String username = prop.getProperty(DATA_SOURCE_USER, "");
@@ -2740,6 +2751,7 @@ public class DataJdbcSource extends AbstractDataSqlSource {
                 throw new SourceException(e);
             }
             clientInfo.put("version", String.valueOf(urlVersion));
+            resetMaxConnection();
         }
 
         @ResourceListener
@@ -2776,52 +2788,101 @@ public class DataJdbcSource extends AbstractDataSqlSource {
             if (newMaxconns != this.maxConns) {
                 ArrayBlockingQueue<Connection> newQueue = new ArrayBlockingQueue<>(newMaxconns);
                 ArrayBlockingQueue<Connection> oldQueue = this.queue;
+                Semaphore oldSemaphore = this.canNewSemaphore;
                 this.queue = newQueue;
                 this.maxConns = newMaxconns;
+                this.canNewSemaphore = new Semaphore(this.maxConns);
                 Connection conn;
                 while ((conn = oldQueue.poll()) != null) {
+                    offerConnection(conn, oldSemaphore);
+                }
+            }
+        }
+
+        private void resetMaxConnection() {
+            if ("mysql".equals(dbtype()) || "postgresql".equals(dbtype())) {
+                int newMaxconns = this.maxConns;
+                Connection conn = pollConnection();
+                try {
+                    Statement stmt = conn.createStatement();
+                    if ("mysql".equals(dbtype())) {
+                        ResultSet rs = stmt.executeQuery("SHOW VARIABLES LIKE 'max_connections'");
+                        if (rs.next()) {
+                            newMaxconns = rs.getInt(2);
+                        }
+                    } else if ("postgresql".equals(dbtype())) {
+                        ResultSet rs = stmt.executeQuery("SHOW max_connections");
+                        if (rs.next()) {
+                            newMaxconns = rs.getInt(1);
+                        }
+                    }
+                    stmt.close();
+                } catch (SQLException e) {
+                } finally {
                     offerConnection(conn);
                 }
+                if (this.maxConns > newMaxconns) { //配置连接数过大
+                    ArrayBlockingQueue<Connection> newQueue = new ArrayBlockingQueue<>(newMaxconns);
+                    ArrayBlockingQueue<Connection> oldQueue = this.queue;
+                    Semaphore oldSemaphore = this.canNewSemaphore;
+                    this.queue = newQueue;
+                    this.maxConns = newMaxconns;
+                    this.canNewSemaphore = new Semaphore(this.maxConns);
+                    Connection c;
+                    while ((c = oldQueue.poll()) != null) {
+                        offerConnection(c, oldSemaphore);
+                    }
+                }
             }
         }
 
         public Connection pollConnection() {
             Connection conn = queue.poll();
             if (conn == null) {
-                if (usingCounter.intValue() >= maxConns) {
-                    try {
-                        conn = queue.poll(connectTimeoutSeconds, TimeUnit.SECONDS);
-                    } catch (InterruptedException t) {
-                        logger.log(Level.WARNING, "take pooled connection error", t);
-                    }
-                    if (conn == null) {
-                        throw new SourceException("create pooled connection timeout");
-                    }
-                }
-            }
-            if (conn != null) {
-                usingCounter.increment();
-                waitingCounter.decrement();
-                if (checkValid(conn)) {
-                    cycleCounter.increment();
-                    return conn;
-                } else {
-                    offerConnection(conn);
-                    conn = null;
-                }
-            }
-            try {
-                conn = driver.connect(url, connectAttrs);
-                conn.setClientInfo(clientInfo);
-            } catch (SQLException ex) {
-                throw new SourceException(ex);
+                return newConnection();
             }
             usingCounter.increment();
-            creatCounter.increment();
-            return conn;
+            if (checkValid(conn)) {
+                cycleCounter.increment();
+                return conn;
+            } else {
+                offerConnection(conn);
+                conn = null;
+            }
+            return newConnection();
+        }
+
+        private Connection newConnection() {
+            Semaphore semaphore = this.canNewSemaphore;
+            Connection conn = null;
+            if (semaphore.tryAcquire()) {
+                try {
+                    conn = driver.connect(url, connectAttrs);
+                    conn.setClientInfo(clientInfo);
+                } catch (SQLException ex) {
+                    throw new SourceException(ex);
+                }
+                usingCounter.increment();
+                creatCounter.increment();
+                return conn;
+            } else {
+                try {
+                    conn = queue.poll(connectTimeoutSeconds, TimeUnit.SECONDS);
+                } catch (InterruptedException t) {
+                    logger.log(Level.WARNING, "take pooled connection error", t);
+                }
+                if (conn == null) {
+                    throw new SourceException("create pooled connection timeout");
+                }
+                return conn;
+            }
         }
 
         public <C> void offerConnection(final C connection) {
+            offerConnection(connection, this.canNewSemaphore);
+        }
+
+        private <C> void offerConnection(final C connection, Semaphore semaphore) {
             Connection conn = (Connection) connection;
             if (conn == null) {
                 return;
@@ -2829,10 +2890,10 @@ public class DataJdbcSource extends AbstractDataSqlSource {
             try {
                 if (checkValid(conn) && queue.offer(conn)) {
                     usingCounter.decrement();
-                    waitingCounter.increment();
                 } else {
                     usingCounter.decrement();
                     closeCounter.increment();
+                    semaphore.release();
                     conn.close();
                 }
             } catch (Exception e) {
diff --git a/src/main/java/org/redkale/source/DataMemorySource.java b/src/main/java/org/redkale/source/DataMemorySource.java
index d370ea88c..6bc84e74f 100644
--- a/src/main/java/org/redkale/source/DataMemorySource.java
+++ b/src/main/java/org/redkale/source/DataMemorySource.java
@@ -40,6 +40,16 @@ public class DataMemorySource extends AbstractDataSqlSource implements SearchSou
         this.cacheForbidden = false;
     }
 
+    @Override
+    protected int readMaxConns() {
+        return -1;
+    }
+
+    @Override
+    protected int writeMaxConns() {
+        return -1;
+    }
+
     @Local
     @Override
     public String getType() {