bonecp回缩功能实现

起因

bonecp不具备回缩功能,即连接池持有连接之后,不会主动去释放这些连接(即使这些连接始终处于空闲状态),因此在使用一段时间之后,连接池会达到配置的最大值。

这种方式一定程度上造成了资源的浪费。

改造

参考tomcat-jdbc的策略,每隔一段时间(可配置)会启动定时任务扫描partition中的idle队列,判断idle连接数是否大于partition可持有的最小连接数,如果是,则启动清理方法,将连接释放掉。

为了达到这个目的,实现了ConnectionCleanThread类:

package com.jolbox.bonecp;

import java.sql.SQLException;
import java.util.concurrent.BlockingQueue;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class ConnectionCleanThread implements Runnable {

	private static final Logger logger = LoggerFactory.getLogger(ConnectionCleanThread.class);
	
	private ConnectionPartition partition;
	
	private BoneCP pool;
	
	protected ConnectionCleanThread(ConnectionPartition connectionPartition, BoneCP pool) {
		this.partition = connectionPartition;
		this.pool = pool;
	}
	
	@Override
	public void run() {
		BlockingQueue freeQueue = null;
		ConnectionHandle connection = null;
		//获得partition的大小
		int partitionSize = this.partition.getAvailableConnections();
		for (int i = 0; i < partitionSize; i++) {
			//得到free连接的queue
			freeQueue = this.partition.getFreeConnections();
			//如果空闲连接大于partition的最小允许连接数,回缩到最小允许连接数
			while (freeQueue.size() > this.partition.getMinConnections()) {
				connection = freeQueue.poll();
				connection.lock();
				closeConnection(connection);
				connection.unlock();
			}
		}
	}
	
	/** Closes off this connection
	 * @param connection to close
	 */
	private void closeConnection(ConnectionHandle connection) {

		if (connection != null && !connection.isClosed()) {
			try {
				connection.internalClose();
			} catch (SQLException e) {
				logger.error("Destroy connection exception", e);
			} finally {
				this.pool.postDestroyConnection(connection);
				connection.getOriginatingPartition().getPoolWatchThreadSignalQueue().offer(new Object()); // item being pushed is not important.
			}
		}
	}

}

同时需要对核心类ConnectionHandle进行改造,加上连接的上锁方法:

protected void lock() {
	lock.writeLock().lock();
}
	
protected void unlock() {
	lock.writeLock().unlock();
}

在BoneCP类的构造器内加上该线程的定时任务:

/**
 * 空闲连接清理任务
*/
private ScheduledExecutorService connectionCleanScheduler;

...

this.connectionCleanScheduler = Executors.newScheduledThreadPool(this.config.getPartitionCount(), new CustomThreadFactory("BoneCP-connection-clean-thread"+suffix, true));

...

//定期启动一个线程清理空闲连接
//add 2017-2-10
final Runnable connectionCleaner = new ConnectionCleanThread(connectionPartition, this);
this.connectionCleanScheduler.scheduleAtFixedRate(connectionCleaner, this.config.getConnectionCleanTimeInSeconds(), this.config.getConnectionCleanTimeInSeconds(), TimeUnit.SECONDS);

效果

经过实际测试,可以在后台自动的回收idle连接。

现在只是实现了功能,各种情况暂时没有加入考虑,比如没有判断该连接是否应该被释放。

GitHub地址

bonecp

posted @ 2017-02-10 20:15  wingsless  阅读(357)  评论(0编辑  收藏  举报