Druid 1.1.24 在控制台打印"discard long time none received connection. , jdbcUrl : jdbc:mysql://....&q
Druid 1.1.24 在控制台打印"discard long time none received connection. , jdbcUrl : jdbc:mysql://..."错误日志
参考资料
- https://q.cnblogs.com/q/133036/
- https://blog.csdn.net/weixin_41613567/article/details/83148800
报错原因
- 我使用的是mysql 数据库,驱动包使用的是mysql-connector-java-8.0.27.jar
- druid 使用的是 druid-1.1.24.jar
- 经过每个包的翻看,在 com.alibaba.druid.pool.vendor 包下查到这个MySqlValidConnectionChecker类 ,根据类名猜测出这个是 MySQL 数据连接校验类.
- MySqlValidConnectionChecker 源码如下:
点击查看代码
public class MySqlValidConnectionChecker extends ValidConnectionCheckerAdapter implements ValidConnectionChecker, Serializable {
public static final int DEFAULT_VALIDATION_QUERY_TIMEOUT = 1;
public static final String DEFAULT_VALIDATION_QUERY = "SELECT 1";
private static final long serialVersionUID = 1L;
private static final Log LOG = LogFactory.getLog(MySqlValidConnectionChecker.class);
private Class<?> clazz;
private Method ping;
private boolean usePingMethod = false;
public MySqlValidConnectionChecker(){
try {
clazz = Utils.loadClass("com.mysql.jdbc.MySQLConnection");
if (clazz == null) {
clazz = Utils.loadClass("com.mysql.cj.jdbc.ConnectionImpl");
}
if (clazz != null) {
ping = clazz.getMethod("pingInternal", boolean.class, int.class);
}
if (ping != null) {
usePingMethod = true;
}
} catch (Exception e) {
LOG.warn("Cannot resolve com.mysql.jdbc.Connection.ping method. Will use 'SELECT 1' instead.", e);
}
configFromProperties(System.getProperties());
}
@Override
public void configFromProperties(Properties properties) {
String property = properties.getProperty("druid.mysql.usePingMethod");
if ("true".equals(property)) {
setUsePingMethod(true);
} else if ("false".equals(property)) {
setUsePingMethod(false);
}
}
public boolean isUsePingMethod() {
return usePingMethod;
}
public void setUsePingMethod(boolean usePingMethod) {
this.usePingMethod = usePingMethod;
}
public boolean isValidConnection(Connection conn, String validateQuery, int validationQueryTimeout) throws Exception {
if (conn.isClosed()) {
return false;
}
if (usePingMethod) {
if (conn instanceof DruidPooledConnection) {
conn = ((DruidPooledConnection) conn).getConnection();
}
if (conn instanceof ConnectionProxy) {
conn = ((ConnectionProxy) conn).getRawObject();
}
if (clazz.isAssignableFrom(conn.getClass())) {
if (validationQueryTimeout <= 0) {
validationQueryTimeout = DEFAULT_VALIDATION_QUERY_TIMEOUT;
}
try {
ping.invoke(conn, true, validationQueryTimeout * 1000);
} catch (InvocationTargetException e) {
Throwable cause = e.getCause();
if (cause instanceof SQLException) {
throw (SQLException) cause;
}
throw e;
}
return true;
}
}
String query = validateQuery;
if (validateQuery == null || validateQuery.isEmpty()) {
query = DEFAULT_VALIDATION_QUERY;
}
Statement stmt = null;
ResultSet rs = null;
try {
stmt = conn.createStatement();
if (validationQueryTimeout > 0) {
stmt.setQueryTimeout(validationQueryTimeout);
}
rs = stmt.executeQuery(query);
return true;
} finally {
JdbcUtils.close(rs);
JdbcUtils.close(stmt);
}
}
}
- 根据源码中 isValidConnection(Connection conn, String validateQuery, int validationQueryTimeout) 方法,有个判断 :
// 如果使用 ping 方法,则会反射调用 ping 方法验证数据库连接是否有效,而不执行 validateQuery 验证.
if (usePingMethod) {
if (conn instanceof DruidPooledConnection) {
conn = ((DruidPooledConnection) conn).getConnection();
}
if (conn instanceof ConnectionProxy) {
conn = ((ConnectionProxy) conn).getRawObject();
}
if (clazz.isAssignableFrom(conn.getClass())) {
if (validationQueryTimeout <= 0) {
validationQueryTimeout = DEFAULT_VALIDATION_QUERY_TIMEOUT;
}
try {
ping.invoke(conn, true, validationQueryTimeout * 1000);
} catch (InvocationTargetException e) {
Throwable cause = e.getCause();
if (cause instanceof SQLException) {
throw (SQLException) cause;
}
throw e;
}
return true;
}
}
那么 usePingMethod 是怎么来的?
查看构造器方法:
public MySqlValidConnectionChecker(){
try {
// 先加载的驱动类
clazz = Utils.loadClass("com.mysql.jdbc.MySQLConnection");
if (clazz == null) {
clazz = Utils.loadClass("com.mysql.cj.jdbc.ConnectionImpl");
}
// 反射获取驱动类的 pingInternal 方法
if (clazz != null) {
ping = clazz.getMethod("pingInternal", boolean.class, int.class);
}
// 若驱动类的 pingInternal 方法如果存在则 usePingMethod = true
if (ping != null) {
usePingMethod = true;
}
} catch (Exception e) {
LOG.warn("Cannot resolve com.mysql.jdbc.Connection.ping method. Will use 'SELECT 1' instead.", e);
}
// 从系统配置文件配置属性,
configFromProperties(System.getProperties());
}
@Override
public void configFromProperties(Properties properties) {
// 从系统属性(JVM启动参数)中获取'druid.mysql.usePingMethod'属性 覆盖 usePingMethod 的值
String property = properties.getProperty("druid.mysql.usePingMethod");
if ("true".equals(property)) {
setUsePingMethod(true);
} else if ("false".equals(property)) {
setUsePingMethod(false);
}
}
以上可以得出结论, 通过配置JVM启动参数"druid.mysql.usePingMethod=false" 告知 Druid 停止使用 usePingMethod 方法验证数据库连接,转而使用 validateQuery 验证.
解决方法
1. JVM启动参数添加如下配置
-Ddruid.mysql.usePingMethod=false