应用升级MySQL驱动8.0后，在并发量较高时，查看监控打点，Druid连接池拿到连接并执行SQL的时间大部分都超过200ms，本文就解决一下这个问题现象 "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)根因分析 public class MySqlUtils {
public static long getLastPacketReceivedTimeMs(Connection conn) throws SQLException {
if (class_connectionImpl == null && !class_connectionImpl_Error) {
try {
class_connectionImpl = Utils.loadClass("com.mysql.jdbc.MySQLConnection");
} catch (Throwable error){
class_connectionImpl_Error = true;
}
}
if (class_connectionImpl == null) {
return -1;
}
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);
}
}public class Utils {
public static Class<?> loadClass(String className) {
Class<?> clazz = null;
if (className == null) {
return null;
}
try {
return Class.forName(className);
} catch (ClassNotFoundException e) {
// skip
}
ClassLoader ctxClassLoader = Thread.currentThread().getContextClassLoader();
if (ctxClassLoader != null) {
try {
clazz = ctxClassLoader.loadClass(className);
} catch (ClassNotFoundException e) {
// skip
}
}
return clazz;
}public Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
synchronized (JreCompat.isGraalAvailable() ? this : getClassLoadingLock(name)) {
Class<?> result = findExistingLoadedClass(name);
result = (result != null) ? result : doLoadClass(name);
if (result == null) {
throw new ClassNotFoundException(name);
}
return resolveIfNecessary(result, resolve);
}
}getLastPacketReceivedTimeMs()方法调用时机 public abstract class DruidAbstractDataSource extends WrapperAdapter implements DruidAbstractDataSourceMBean, DataSource, DataSourceProxy, Serializable {
protected boolean testConnectionInternal(DruidConnectionHolder holder, Connection conn) {
String sqlFile = JdbcSqlStat.getContextSqlFile();
String sqlName = JdbcSqlStat.getContextSqlName();
if (sqlFile != null) {
JdbcSqlStat.setContextSqlFile(null);
}
if (sqlName != null) {
JdbcSqlStat.setContextSqlName(null);
}
try {
if (validConnectionChecker != null) {
boolean valid = validConnectionChecker.isValidConnection(conn, validationQuery, validationQueryTimeout);
long currentTimeMillis = System.currentTimeMillis();
if (holder != null) {
holder.lastValidTimeMillis = currentTimeMillis;
holder.lastExecTimeMillis = currentTimeMillis;
}
if (valid && isMySql) { // unexcepted branch
long lastPacketReceivedTimeMs = MySqlUtils.getLastPacketReceivedTimeMs(conn);
if (lastPacketReceivedTimeMs > 0) {
long mysqlIdleMillis = currentTimeMillis - lastPacketReceivedTimeMs;
if (lastPacketReceivedTimeMs > 0 //
&& mysqlIdleMillis >= timeBetweenEvictionRunsMillis) {
discardConnection(holder);
String errorMsg = "discard long time none received connection. "
+ ", jdbcUrl : " + jdbcUrl
+ ", jdbcUrl : " + jdbcUrl
+ ", lastPacketReceivedIdleMillis : " + mysqlIdleMillis;
LOG.error(errorMsg);
return false;
}
}
}
if (valid && onFatalError) {
lock.lock();
try {
if (onFatalError) {
onFatalError = false;
}
} finally {
lock.unlock();
}
}
return valid;
}
if (conn.isClosed()) {
return false;
}
if (null == validationQuery) {
return true;
}
Statement stmt = null;
ResultSet rset = null;
try {
stmt = conn.createStatement();
if (getValidationQueryTimeout() > 0) {
stmt.setQueryTimeout(validationQueryTimeout);
}
rset = stmt.executeQuery(validationQuery);
if (!rset.next()) {
return false;
}
} finally {
JdbcUtils.close(rset);
JdbcUtils.close(stmt);
}
if (onFatalError) {
lock.lock();
try {
if (onFatalError) {
onFatalError = false;
}
} finally {
lock.unlock();
}
}
return true;
} catch (Throwable ex) {
// skip
return false;
} finally {
if (sqlFile != null) {
JdbcSqlStat.setContextSqlFile(sqlFile);
}
if (sqlName != null) {
JdbcSqlStat.setContextSqlName(sqlName);
}
}
}testOnBorrow：每次获取连接时执行validationQuery检测连接是否有效（会影响性能） testOnReturn：每次归还连接时执行validationQuery检测连接是否有效（会影响性能） testWhileIdle：申请连接的时候检测，如果空闲时间大于timeBetweenEvictionRunsMillis，执行validationQuery检测连接是否有效 应用中设置了testOnBorrow=true，每次获取连接时，都会去抢占synchronized锁，所以性能下降的很明显 解决方案 CodeAE代码之家 以前的文章或继续浏览下面的相关文章希望大家以后多多支持CodeAE代码之家！ 
数据库
发布于：2021-08-28 14:02
|
阅读数：463
|
评论：0
QQ好友和群
QQ空间
