com.alibaba:druid:1.1.20 MysqlUtils写死了mysql-connector-java 5.1版本的MySQLConnection类加载，导致线程阻塞，性能受限

[devonkey]

升级新版 mysql-connector-java至8.0.x后，系统进行压测，出现

"http-nio-5366-exec-48" #210 daemon prio=5 os_prio=0 tid=0x00000000023d0800 nid=0x3be9 waiting for monitor entry [0x00007fa4c1400000]
   java.lang.Thread.State: BLOCKED (on object monitor)
        at org.springframework.boot.web.embedded.tomcat.TomcatEmbeddedWebappClassLoader.loadClass(TomcatEmbeddedWebappClassLoader.java:66)
        - waiting to lock <0x0000000775af0960> (a java.lang.Object)
        at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1186)
        at com.alibaba.druid.util.Utils.loadClass(Utils.java:220)
        at com.alibaba.druid.util.MySqlUtils.getLastPacketReceivedTimeMs(MySqlUtils.java:372)

大量线程阻塞，发现
class_connectionImpl = Utils.loadClass("com.mysql.jdbc.MySQLConnection"); 中的 com.mysql.jdbc.MySQLConnection在新版本中不存在，同时
Utils.loadClass方法类加载生吞了异常，所以代码逻辑会频繁对不存在的类进行类加载

[devonkey]

mysql-connector-java 降低到5.1.49，同时mysql driver-class 从 com.mysql.cj.jdbc.Driver 改为 com.mysql.jdbc.Driver 性能得到有效提高

[beiwangnull]

我也碰到了，mysql-connector 8.X的驱动，从代码看，当idleMillis >= timeBetweenEvictionRunsMillis就会出现这个问题

[beiwangnull]

`/*

• Copyright 1999-2018 Alibaba Group Holding Ltd.
• Licensed under the Apache License, Version 2.0 (the "License");
• you may not use this file except in compliance with the License.
• You may obtain a copy of the License at

•  http://www.apache.org/licenses/LICENSE-2.0
  

• Unless required by applicable law or agreed to in writing, software
• distributed under the License is distributed on an "AS IS" BASIS,
• WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
• See the License for the specific language governing permissions and
• limitations under the License.
  */
  package com.alibaba.druid.util;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.Connection;
import java.sql.Driver;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.SQLFeatureNotSupportedException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import javax.sql.XAConnection;

import com.alibaba.druid.sql.SQLUtils;
import com.alibaba.druid.sql.ast.statement.SQLCreateTableStatement;

public class MySqlUtils {
static Class<?> utilClass;
static boolean utilClassError = false;
static boolean utilClass_isJdbc4 = false;

static Class<?>       class_5_connection= null;
static Method         method_5_getPinGlobalTxToPhysicalConnection = null;
static Class<?>       class_5_suspendableXAConnection = null;
static Constructor<?> constructor_5_suspendableXAConnection = null;
static Class<?>       class_5_JDBC4SuspendableXAConnection = null;
static Constructor<?> constructor_5_JDBC4SuspendableXAConnection = null;
static Class<?>       class_5_MysqlXAConnection = null;
static Constructor<?> constructor_5_MysqlXAConnection = null;

static Class<?>       class_ConnectionImpl = null;
static Method         method_getId = null;
static boolean        method_getId_error = false;

static Class<?>       class_6_ConnectionImpl = null;
static Method         method_6_getId         = null;

volatile static Class<?>       class_6_connection= null;
volatile static Method         method_6_getPropertySet = null;
volatile static Method         method_6_getBooleanReadableProperty = null;
volatile static Method         method_6_getValue = null;
volatile static boolean        method_6_getValue_error = false;

volatile static Class<?>       class_6_suspendableXAConnection = null;
volatile static Method         method_6_getInstance = null;
volatile static boolean        method_6_getInstance_error = false;
volatile static Method         method_6_getInstanceXA = null;
volatile static boolean        method_6_getInstanceXA_error = false;
volatile static Class<?>       class_6_JDBC4SuspendableXAConnection = null;



public static XAConnection createXAConnection(Driver driver, Connection physicalConn) throws SQLException {
    final int major = driver.getMajorVersion();
    if (major == 5) {
        if (utilClass == null && !utilClassError) {
            try {
                utilClass = Class.forName("com.mysql.jdbc.Util");

                Method method = utilClass.getMethod("isJdbc4");
                utilClass_isJdbc4 = (Boolean) method.invoke(null);

                class_5_connection = Class.forName("com.mysql.jdbc.Connection");
                method_5_getPinGlobalTxToPhysicalConnection = class_5_connection.getMethod("getPinGlobalTxToPhysicalConnection");

                class_5_suspendableXAConnection = Class.forName("com.mysql.jdbc.jdbc2.optional.SuspendableXAConnection");
                constructor_5_suspendableXAConnection = class_5_suspendableXAConnection.getConstructor(class_5_connection);

                class_5_JDBC4SuspendableXAConnection = Class.forName("com.mysql.jdbc.jdbc2.optional.JDBC4SuspendableXAConnection");
                constructor_5_JDBC4SuspendableXAConnection = class_5_JDBC4SuspendableXAConnection.getConstructor(class_5_connection);

                class_5_MysqlXAConnection = Class.forName("com.mysql.jdbc.jdbc2.optional.MysqlXAConnection");
                constructor_5_MysqlXAConnection = class_5_MysqlXAConnection.getConstructor(class_5_connection, boolean.class);
            } catch (Exception ex) {
                ex.printStackTrace();
                utilClassError = true;
            }
        }

        try {
            boolean pinGlobTx = (Boolean) method_5_getPinGlobalTxToPhysicalConnection.invoke(physicalConn);
            if (pinGlobTx) {
                if (!utilClass_isJdbc4) {
                    return (XAConnection) constructor_5_suspendableXAConnection.newInstance(physicalConn);
                }

                return (XAConnection) constructor_5_JDBC4SuspendableXAConnection.newInstance(physicalConn);
            }

            return (XAConnection) constructor_5_MysqlXAConnection.newInstance(physicalConn, Boolean.FALSE);
        } catch (Exception e) {
            e.printStackTrace();
        }

    } else if (major == 6 || major == 8) {
        if (method_6_getValue == null && !method_6_getValue_error) {
            try {
                class_6_connection = Class.forName("com.mysql.cj.api.jdbc.JdbcConnection");
            } catch (Throwable t) {
            }

            try {
                // maybe 8.0.11 or higher version, try again with com.mysql.cj.jdbc.JdbcConnection
                if (class_6_connection == null) {
                    class_6_connection = Class.forName("com.mysql.cj.jdbc.JdbcConnection");
                    method_6_getPropertySet = class_6_connection.getMethod("getPropertySet");
                    method_6_getBooleanReadableProperty = Class.forName("com.mysql.cj.conf.PropertySet").getMethod("getBooleanReadableProperty", String.class);
                    method_6_getValue = Class.forName("com.mysql.cj.conf.ReadableProperty").getMethod("getValue");
                }
                else {
                    method_6_getPropertySet = class_6_connection.getMethod("getPropertySet");
                    method_6_getBooleanReadableProperty = Class.forName("com.mysql.cj.api.conf.PropertySet").getMethod("getBooleanReadableProperty", String.class);
                    method_6_getValue = Class.forName("com.mysql.cj.api.conf.ReadableProperty").getMethod("getValue");
                }
            } catch (Exception ex) {
                ex.printStackTrace();
                method_6_getValue_error = true;
            }
        }

        try {
            // pinGlobalTxToPhysicalConnection
            Boolean pinGlobTx = (Boolean) method_6_getValue.invoke(
                method_6_getBooleanReadableProperty.invoke(
                    method_6_getPropertySet.invoke(physicalConn)
                    , "pinGlobalTxToPhysicalConnection"
                )
            );

            if (pinGlobTx != null && pinGlobTx) {
                try {
                    if (method_6_getInstance == null && !method_6_getInstance_error) {
                        class_6_suspendableXAConnection = Class.forName("com.mysql.cj.jdbc.SuspendableXAConnection");
                        method_6_getInstance = class_6_suspendableXAConnection.getDeclaredMethod("getInstance", class_6_connection);
                        method_6_getInstance.setAccessible(true);
                    }
                } catch (Throwable ex) {
                    ex.printStackTrace();
                    method_6_getInstance_error = true;
                }
                return (XAConnection) method_6_getInstance.invoke(null, physicalConn);
            } else {
                try {
                    if (method_6_getInstanceXA == null && !method_6_getInstanceXA_error) {
                        class_6_JDBC4SuspendableXAConnection = Class.forName("com.mysql.cj.jdbc.MysqlXAConnection");
                        method_6_getInstanceXA = class_6_JDBC4SuspendableXAConnection.getDeclaredMethod("getInstance", class_6_connection, boolean.class);
                        method_6_getInstanceXA.setAccessible(true);
                    }
                } catch (Throwable ex) {
                    ex.printStackTrace();
                    method_6_getInstanceXA_error = true;
                }
                return (XAConnection) method_6_getInstanceXA.invoke(null, physicalConn, Boolean.FALSE);
            }
        } catch (InvocationTargetException e) {
            Throwable cause = e.getCause();
            if (cause instanceof RuntimeException) {
                throw (RuntimeException) cause;
            }
        } catch (Exception e) {
            e.printStackTrace();
            method_6_getInstance_error = true;
        }
    }

    throw new SQLFeatureNotSupportedException();
}

public static String buildKillQuerySql(Connection connection, SQLException error) throws SQLException {
    Long threadId = getId(connection);
    if (threadId == null) {
        return null;
    }

    return  "KILL QUERY " + threadId;

}

private static Set<String> keywords;

public static boolean isKeyword(String name) {
    if (name == null) {
        return false;
    }

    String name_lower = name.toLowerCase();

    Set<String> words = keywords;

    if (words == null) {
        words = new HashSet<String>();
        Utils.loadFromFile("META-INF/druid/parser/mysql/keywords", words);
        keywords = words;
    }

    return words.contains(name_lower);
}

private static Set<String> builtinDataTypes;

public static boolean isBuiltinDataType(String dataType) {
    if (dataType == null) {
        return false;
    }

    String table_lower = dataType.toLowerCase();

    Set<String> dataTypes = builtinDataTypes;

    if (dataTypes == null) {
        dataTypes = new HashSet<String>();
        Utils.loadFromFile("META-INF/druid/parser/mysql/builtin_datatypes", dataTypes);
        builtinDataTypes = dataTypes;
    }

    return dataTypes.contains(table_lower);
}

public static List<String> showTables(Connection conn) throws SQLException {
    List<String> tables = new ArrayList<String>();

    Statement stmt = null;
    ResultSet rs = null;
    try {
        stmt = conn.createStatement();
        rs = stmt.executeQuery("show tables");
        while (rs.next()) {
            String tableName = rs.getString(1);
            tables.add(tableName);
        }
    } finally {
        JdbcUtils.close(rs);
        JdbcUtils.close(stmt);
    }

    return tables;
}

public static List<String> getTableDDL(Connection conn, List<String> tables) throws SQLException {
    List<String> ddlList = new ArrayList<String>();

    Statement stmt = null;
    try {
        for (String table : tables) {
            if (stmt == null) {
                stmt = conn.createStatement();
            }

            if (isKeyword(table)) {
                table = "`" + table + "`";
            }

            ResultSet rs = null;
            try {
                rs = stmt.executeQuery("show create table " + table);
                if (rs.next()) {
                    String ddl = rs.getString(2);
                    ddlList.add(ddl);
                }
            } finally {
                JdbcUtils.close(rs);
            }
        }
    } finally {
        JdbcUtils.close(stmt);
    }


    return ddlList;
}

public static String getCreateTableScript(Connection conn) throws SQLException {
    return getCreateTableScript(conn, true, true);
}

public static String getCreateTableScript(Connection conn, boolean sorted, boolean simplify) throws SQLException {
    List<String> tables = showTables(conn);
    List<String> ddlList = getTableDDL(conn, tables);
    StringBuilder buf = new StringBuilder();
    for (String ddl : ddlList) {
        buf.append(ddl);
        buf.append(';');
    }
    String ddlScript = buf.toString();

    if (! (sorted || simplify)) {
        return ddlScript;
    }

    List stmtList = SQLUtils.parseStatements(ddlScript, JdbcConstants.MYSQL);
    if (simplify) {
        for (Object o : stmtList) {
            if (o instanceof SQLCreateTableStatement) {
                SQLCreateTableStatement createTableStmt = (SQLCreateTableStatement) o;
                createTableStmt.simplify();
            }
        }
    }

    if (sorted) {
        SQLCreateTableStatement.sort(stmtList);
    }
    return SQLUtils.toSQLString(stmtList, JdbcConstants.MYSQL);
}

private static transient Class   class_connectionImpl                     = null;
private static transient boolean class_connectionImpl_Error               = false;
private static transient Method  method_getIO                             = null;
private static transient boolean method_getIO_error                       = false;
private static transient Class   class_MysqlIO                            = null;
private static transient boolean class_MysqlIO_Error                      = false;
private static transient Method  method_getLastPacketReceivedTimeMs       = null;
private static transient boolean method_getLastPacketReceivedTimeMs_error = false;

private volatile static  boolean mysqlJdbcVersion6                        = false;
private static transient Class   classJdbc                                = null;
private static transient Method  getIdleFor                               = null;
private static transient boolean getIdleForError                          = false;

public static Long getId(Object conn) {
    if (conn == null) {
        return null;
    }

    Class<?> clazz = conn.getClass();
    if (class_ConnectionImpl == null) {
        if (clazz.getName().equals("com.mysql.jdbc.ConnectionImpl")) {
            class_ConnectionImpl = clazz;
        } else if (clazz.getName().equals("com.mysql.jdbc.Connection")) { // mysql 5.0.x
            class_ConnectionImpl = clazz;
        } else if (clazz.getName().equals("com.mysql.cj.jdbc.ConnectionImpl")) { // mysql 5.0.x
            class_ConnectionImpl = clazz;
        } else if (clazz.getSuperclass().getName().equals("com.mysql.jdbc.ConnectionImpl")) {
            class_ConnectionImpl = clazz.getSuperclass();
        }
    }

    if (class_ConnectionImpl == clazz || class_ConnectionImpl == clazz.getSuperclass()) {
        try {
            if (method_getId == null && !method_getId_error) {
                Method method = class_ConnectionImpl.getDeclaredMethod("getId");
                method.setAccessible(true);
                method_getId = method;
            }

            return (Long) method_getId.invoke(conn);
        } catch (Throwable ex) {
            method_getId_error = true;
        }
    }

    return null;
}

public static long getLastPacketReceivedTimeMs(Connection conn) throws SQLException {
    if (class_connectionImpl == null && !class_connectionImpl_Error) {
        try {
            class_connectionImpl = Utils.loadClass("com.mysql.jdbc.MySQLConnection");
            if(null == class_connectionImpl){
                class_connectionImpl = Utils.loadClass("com.mysql.cj.MysqlConnection");
                if(null != class_connectionImpl){
                    mysqlJdbcVersion6 = true;
                }
            }
        } catch (Throwable error){
            class_connectionImpl_Error = true;
        }
    }

    if (class_connectionImpl == null) {
        return -1;
    }

    if(mysqlJdbcVersion6){
        if(null == classJdbc) {
            classJdbc = Utils.loadClass("com.mysql.cj.jdbc.JdbcConnection");
        }
        if(null == classJdbc){
            return -1;
        }
        if(null == getIdleFor && !getIdleForError) {
            try {
                getIdleFor = classJdbc.getMethod("getIdleFor");
                getIdleFor.setAccessible(true);
            } catch (Throwable error) {
                getIdleForError = true;
            }
        }
        if (getIdleFor == null) {
            return -1;
        }
        try {
            Object connImpl = conn.unwrap(class_connectionImpl);
            if (connImpl == null) {
                return -1;
            }
            Long ms = (long)getIdleFor.invoke(connImpl);
            return 0 == ms.longValue()?System.currentTimeMillis() : System.currentTimeMillis()-ms.longValue();
        } catch (IllegalAccessException e) {
            throw new SQLException("getIdleFor error", e);
        } catch (InvocationTargetException e) {
            throw new SQLException("getIdleFor error", e);
        }
    }else {

        if (method_getIO == null && !method_getIO_error) {
            try {
                method_getIO = class_connectionImpl.getMethod("getIO");
            } catch (Throwable error) {
                method_getIO_error = true;
            }
        }

        if (method_getIO == null) {
            return -1;
        }

        if (class_MysqlIO == null && !class_MysqlIO_Error) {
            try {
                class_MysqlIO = Utils.loadClass("com.mysql.jdbc.MysqlIO");
            } catch (Throwable error) {
                class_MysqlIO_Error = true;
            }
        }

        if (class_MysqlIO == null) {
            return -1;
        }

        if (method_getLastPacketReceivedTimeMs == null && !method_getLastPacketReceivedTimeMs_error) {
            try {
                Method method = class_MysqlIO.getDeclaredMethod("getLastPacketReceivedTimeMs");
                method.setAccessible(true);
                method_getLastPacketReceivedTimeMs = method;
            } catch (Throwable error) {
                method_getLastPacketReceivedTimeMs_error = true;
            }
        }

        if (method_getLastPacketReceivedTimeMs == null) {
            return -1;
        }

        try {
            Object connImpl = conn.unwrap(class_connectionImpl);
            if (connImpl == null) {
                return -1;
            }

            Object mysqlio = method_getIO.invoke(connImpl);
            Long ms = (Long)method_getLastPacketReceivedTimeMs.invoke(mysqlio);
            return ms.longValue();
        } catch (IllegalArgumentException e) {
            throw new SQLException("getLastPacketReceivedTimeMs error", e);
        } catch (IllegalAccessException e) {
            throw new SQLException("getLastPacketReceivedTimeMs error", e);
        } catch (InvocationTargetException e) {
            throw new SQLException("getLastPacketReceivedTimeMs error", e);
        }
    }
}

static Class<?> class_5_CommunicationsException = null;
static Class<?> class_6_CommunicationsException = null;

public static Class getCommunicationsExceptionClass() {
    if (class_5_CommunicationsException != null) {
        return class_5_CommunicationsException;
    }

    if (class_6_CommunicationsException != null) {
        return class_6_CommunicationsException;
    }

    class_5_CommunicationsException = Utils.loadClass("com.mysql.jdbc.CommunicationsException");
    if (class_5_CommunicationsException != null) {
        return class_5_CommunicationsException;
    }

    class_6_CommunicationsException = Utils.loadClass("com.mysql.cj.jdbc.exceptions.CommunicationsException");
    if (class_6_CommunicationsException != null) {
        return class_6_CommunicationsException;
    }

    return null;
}

}
`

[beiwangnull]

mysql-connector-java 降低到5.1.49，同时mysql driver-class 从 com.mysql.cj.jdbc.Driver 改为 com.mysql.jdbc.Driver 性能得到有效提高

可以试下我贴的代码，把MySqlUtils文件替换下，再压下

[yhr577]

看了下更新的,改成这样了,终于不报错了....
this.clazz = Utils.loadClass("com.mysql.jdbc.MySQLConnection"); if (this.clazz == null) { this.clazz = Utils.loadClass("com.mysql.cj.jdbc.ConnectionImpl"); }

[qsLI]

我也遇到了。。。还很隐蔽，突然一波tomcat连接线程的busy。抓了线程栈，分析才找到这里