maximum-active-time

maximum-active-time：表示连接的最大活动时间，即这个连接在指定的时间内没有完成任务（如查询），将 
org.logicalcobwebs.proxool.HouseKeeper 是一个后台线程 用于监控线程池的：

                   if (activeTime > definition.getMaximumActiveTime()) {

                       // This connection has been active for way too long. We're
                       // going to kill it :)
                       connectionPool.removeProxyConnection(proxyConnection, ConnectionListenerIF.MAXIMUM_ACTIVE_TIME_EXPIRED, 
                               "it has been active for too long", ConnectionPool.FORCE_EXPIRY, true);

1、这段代码用于检查线程池中的每个连接是否超过了最大获得时间 
2、如果超过了，会调用connectionPool.removeProxyConnection回收连接 

 

protected void removeProxyConnection(ProxyConnectionIF proxyConnection, int reasonCode, String reason, boolean forceExpiry, boolean triggerSweep) {
        // Just check that it is null
        if (forceExpiry || proxyConnection.isNull()) {

            proxyConnection.setStatus(ProxyConnectionIF.STATUS_NULL);

            /* Run some code everytime we destroy a connection */

            try {
                onDeath(proxyConnection.getConnection(), reasonCode);
            } catch (SQLException e) {
                log.error("Problem during onDeath (ignored)", e);
            }

            // The reallyClose() method also decrements the connectionCount.
            try {
                proxyConnection.reallyClose();
            } catch (SQLException e) {
                log.error(e);
            }

            try {
                // If we're shutting down then getting a write lock will cause a deadlock
                if (isConnectionPoolUp()) {
                    acquireConnectionStatusWriteLock();
                }
                proxyConnections.remove(proxyConnection);
            } finally {
                if (isConnectionPoolUp()) {
                    releaseConnectionStatusWriteLock();
                }
            }

            if (log.isDebugEnabled()) {
                log.debug(displayStatistics() + " - #" + FormatHelper.formatMediumNumber(proxyConnection.getId())
                        + " removed because " + reason + ".");
            }

            if (triggerSweep) {
                PrototyperController.triggerSweep(getDefinition().getAlias());
            }

        } else {
            log.error(displayStatistics() + " - #" + FormatHelper.formatMediumNumber(proxyConnection.getId())
                    + " was not removed because isNull() was false.");
        }
    }

 

proxyConnection.reallyClose();这句话会关闭真实的connection 并放回到连接池。 

一定要注意：我们用了proxool后 返回给我们的connection是一个代理的连接，代理连接执行时再委托给真实的JDBC连接。 

HouseKeeper 就是一个后台线程 定期检查连接的健康状况。

（转载）