DBCP 1.4 BUG 導致連接池爆滿解決方案

dubbo 項目用的 commons-dbcp-1.4  和  commons-pool-1.5.4 實現連接池，導致數據庫經常爆滿，經過調試，發現了個 dbcp的bug：

 

dbcp 源碼：

 

BasicDataSource.java

創建datasource的方法：

protected synchronized DataSource createDataSource()
        throws SQLException {
        if (closed) {
            throw new SQLException("Data source is closed");
        }

        // Return the pool if we have already created it
        if (dataSource != null) {
            return (dataSource);
        }

        // create factory which returns raw physical connections
        ConnectionFactory driverConnectionFactory = createConnectionFactory();

        // create a pool for our connections
        createConnectionPool();

        // Set up statement pool, if desired
        GenericKeyedObjectPoolFactory statementPoolFactory = null;
        if (isPoolPreparedStatements()) {
            statementPoolFactory = new GenericKeyedObjectPoolFactory(null,
                        -1, // unlimited maxActive (per key)
                        GenericKeyedObjectPool.WHEN_EXHAUSTED_FAIL,
                        0, // maxWait
                        1, // maxIdle (per key)
                        maxOpenPreparedStatements);
        }

        // Set up the poolable connection factory
        createPoolableConnectionFactory(driverConnectionFactory, statementPoolFactory, abandonedConfig);

        // Create and return the pooling data source to manage the connections
        createDataSourceInstance();
        
        try {
            for (int i = 0 ; i < initialSize ; i++) {
                connectionPool.addObject();
            }
        } catch (Exception e) {
            throw new SQLNestedException("Error preloading the connection pool", e);
        }
        
        return dataSource;
    }

 

該方法先 調用 createConnectionPool() 方法 創建 connectionPool，

接着 調用 createPoolableConnectionFactory() 方法創建 connectionFactory,

最后 再調用 createDataSourceInstance() 方法創建 datasource

 

 

看看 createConnectionPool() 方法實現：

protected void createConnectionPool() {
        // Create an object pool to contain our active connections
        GenericObjectPool gop;
        if ((abandonedConfig != null) && (abandonedConfig.getRemoveAbandoned())) {
            gop = new AbandonedObjectPool(null,abandonedConfig);
        }
        else {
            gop = new GenericObjectPool();
        }
        gop.setMaxActive(maxActive);
        gop.setMaxIdle(maxIdle);
        gop.setMinIdle(minIdle);
        gop.setMaxWait(maxWait);
        gop.setTestOnBorrow(testOnBorrow);
        gop.setTestOnReturn(testOnReturn);
        gop.setTimeBetweenEvictionRunsMillis(timeBetweenEvictionRunsMillis);
        gop.setNumTestsPerEvictionRun(numTestsPerEvictionRun);
        gop.setMinEvictableIdleTimeMillis(minEvictableIdleTimeMillis);
        gop.setTestWhileIdle(testWhileIdle);
        connectionPool = gop;
    }

 

這個方法是：每次調用都會創建一個connectionPool，並且都是直接new 的，

 

問題：

當創建 connectionPool成功，但是創建connectionFactory失敗，也就是說createConnectionPool()成功了，但是createPoolableConnectionFactory()出現異常了，則dataSource也創建失敗，系統會再次執行 createDataSource() 方法，會再次創建一個新的 coonnectionPool , 我的系統里，一共嘗試創建了 15次都失敗，最后16次才成功，所以也就創建了16個connectionPool,每一個pool的連接數會至少等於 minIdel 的數量，結果導致數據庫連接爆滿。。。

 

解決:

 

修改 createConnectionPool() 方法實現,添加非空判斷：

    protected void createConnectionPool() {
        //添加非空判斷
        if(gop != null){
            return ;
        } 
        // Create an object pool to contain our active connections
        GenericObjectPool gop;
        if ((abandonedConfig != null) && (abandonedConfig.getRemoveAbandoned())) {
            gop = new AbandonedObjectPool(null,abandonedConfig);
        }
        else {
            gop = new GenericObjectPool();
        }
        gop.setMaxActive(maxActive);
        gop.setMaxIdle(maxIdle);
        gop.setMinIdle(minIdle);
        gop.setMaxWait(maxWait);
        gop.setTestOnBorrow(testOnBorrow);
        gop.setTestOnReturn(testOnReturn);
        gop.setTimeBetweenEvictionRunsMillis(timeBetweenEvictionRunsMillis);
        gop.setNumTestsPerEvictionRun(numTestsPerEvictionRun);
        gop.setMinEvictableIdleTimeMillis(minEvictableIdleTimeMillis);
        gop.setTestWhileIdle(testWhileIdle);
        connectionPool = gop;
    }

 

至此：問題解決。