Druid连接池 一个设置 removeAbandonedTimeout 博客分类： 数据库
<!-- 超过时间限制是否回收 --><property name="removeAbandoned" value="true" />
<!-- 超时时间；单位为秒。180秒=3分钟 --><property name="removeAbandonedTimeout" value="180" />
<!-- 关闭abanded连接时输出错误日志 --><property name="logAbandoned" value="true" />
使用druid连接池的超时回收机制排查连接泄露问题
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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,
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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)
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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,:
恩, 这个DestroyConnectionThread非常可疑, 跳
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if (isRemoveAbandoned()) {
removeAbandoned();
}
继续
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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
}
擦, 这里不对头, timeMillis >= removeAbandonedTimeoutMillis timeMillis 这个是getConnection()被调用时的时间
意思就是一个连接被get后, 超过了 removeAbandonedTimeoutMillis这么久我就弄死你.
然后继续找removeAbandonedTimeoutMillis 这玩意在哪里设置的 ,最后发现是在
<property name="removeAbandoned" value="true" /> <property name="removeAbandonedTimeout" value="1800" />初始化配置的这里设置的, 这两个参数的大概意思就是,
通过datasource.getConnontion() 取得的连接必须在removeAbandonedTimeout这么多秒内调用close(),要不我就弄死你.(就是conn不能超过指定的租期)
然后调成2个小时~~~
然后程序成功跑完~~~华丽丽的等了50分钟
总结:
连接池为了防止程序从池里取得连接后忘记归还的情况, 而提供了一些参数来设置一个租期, 使用这个可以在一定程度上防止连接泄漏
但是如果你的业务真要跑这么久~~~~那还是注意下这个设置.