Druid连接池一个设置引发的血案

Posted 2020-09-21 再见理想

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https://my.oschina.net/haogrgr/blog/224010

今天在一台配置很低的机器上运行批量更新的程序~~~

大概跑了三十分钟~~~这配置~~~这程序~~~

然后华丽丽的报异常了~~~

具体异常是这样的,

DEBUG: (BaseJdbcLogger.java:132)    ooo Using Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@4d4e22e1]
[2014-07-17 15:19:35]5363945354 [Druid-ConnectionPool-Destory-1422598563] com.alibaba.druid.pool.DruidDataSource:1132 
WARN : (DruidDataSource.java:1132)   get/close not same thread

ERROR: (DruidDataSource.java:1815)   abandon connection, open stackTrace
        at java.lang.Thread.getStackTrace(Thread.java:1588)
	at com.alibaba.druid.pool.DruidDataSource.getConnectionDirect(DruidDataSource.java:942)
	at com.alibaba.druid.filter.FilterChainImpl.dataSource_connect(FilterChainImpl.java:4534)
	at com.alibaba.druid.filter.stat.StatFilter.dataSource_getConnection(StatFilter.java:661)
	at com.alibaba.druid.filter.FilterChainImpl.dataSource_connect(FilterChainImpl.java:4530)
	at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:880)
	at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:872)
	at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:97)

这个是最初的异常, 后面还有一大批异常,

Caused by: java.sql.SQLException: connection holder is null
	at com.alibaba.druid.pool.DruidPooledConnection.checkState(DruidPooledConnection.java:1085)
	at com.alibaba.druid.pool.DruidPooledConnection.getMetaData(DruidPooledConnection.java:825)
	at org.springframework.jdbc.support.JdbcUtils.extractDatabaseMetaData(JdbcUtils.java:285)
	... 70 more

说什么holder为空

第一眼看到holder就像到Spring的源码, 里面到处是holder(笑)

但是这里的holder不是Spirng里面的,是Druid的

这个holder大概是用来hou住连接池里面的连接的.

然后为什么为空了呢? 目测是哪个链接坏了, 或者被意外的关闭了...

根据异常调源码 at com.alibaba.druid.pool.DruidDataSource.getConnectionDirect(DruidDataSource.java:942)

941         if (isRemoveAbandoned()) {
942                StackTraceElement[] stackTrace = Thread.currentThread().getStackTrace();
943                poolalbeConnection.setConnectStackTrace(stackTrace);
                poolalbeConnection.setConnectedTimeNano();
                poolalbeConnection.setTraceEnable(true);

                synchronized (activeConnections) {
                    activeConnections.put(poolalbeConnection, PRESENT);
                }
            }

看不出啥来. 只能将日志继续看看, 还是看不出啥来

然后看了上面代码几遍后, 老觉得 isRemoveAbandoned() 这个方法有鬼.

查看调用处,:

技术分享

恩, 这个DestroyConnectionThread非常可疑, 跳

                    if (isRemoveAbandoned()) {
                        removeAbandoned();
                    }

继续

    public int removeAbandoned() {
        int removeCount = 0;

        long currrentNanos = System.nanoTime();

        List<DruidPooledConnection> abandonedList = new ArrayList<DruidPooledConnection>();

        synchronized (activeConnections) {
            Iterator<DruidPooledConnection> iter = activeConnections.keySet().iterator();

            for (; iter.hasNext();) {
                DruidPooledConnection pooledConnection = iter.next();

                if (pooledConnection.isRunning()) {
                    continue;
                }

                long timeMillis = (currrentNanos - pooledConnection.getConnectedTimeNano()) / (1000 * 1000);

                if (timeMillis >= removeAbandonedTimeoutMillis) {
                    iter.remove();
                    pooledConnection.setTraceEnable(false);
                    abandonedList.add(pooledConnection);
                }
            }
        } ....略
    }