Hibernate应用程序部署在WebSphere AS 上出现记录死锁的分析与解决

2007-04-14 | 阅读(534)

有一个项目，是用Hibernate开发的部署在WebSphere Application Server 5.1下，总是会出现数据库记录被死锁的情况，即使是一个简单的更新动作，都有可能造成。

这个问题，困扰我许久，检查过所有代码，事物一定要提交或者回滚，Session及时释放，怀疑过是否是因为是部署在集群环境，但好像那些措施总于事无补，百思不得其解。

就差没有使用容器提供的事物了。

突然间想到去各自的官网，查查有没有人碰到过类似的信息，于是在 http://www.hibernate.org 网站找到了Hibernate in WAS 5.x - fixes possible deadlock problem，其中提到要定制一个 ConnectionProvider，名之为 WSDataSourceConnectionProvider，代码如下：

package com.unmi.db;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;

import org.apache.log4j.Logger;
import org.hibernate.HibernateException;
import org.hibernate.cfg.Environment;
import org.hibernate.connection.ConnectionProvider;
import org.hibernate.util.NamingHelper;

import com.ibm.websphere.rsadapter.JDBCConnectionSpec;
import com.ibm.websphere.rsadapter.WSCallHelper;
import com.ibm.websphere.rsadapter.WSDataSource;
import com.ibm.websphere.rsadapter.WSRRAFactory;
import com.ibm.ws.rsadapter.jdbc.WSJdbcConnection;
import com.ibm.ws.rsadapter.jdbc.WSJdbcUtil;

/**
 * ConnectionProvider implementation that implements WSDataSource specific
 * Transaction Isolation level settings for the connection. Modified from the
 * original DatasourceConnectionProvider class by Lari Hotari
 *
 */
public class WSDataSourceConnectionProvider implements ConnectionProvider {
    public boolean supportsAggressiveRelease() {
        return false;
    }

    private WSDataSource ds;
    private String user;
    private String pass;
    private Integer isolation;

    private static final Logger log = Logger
            .getLogger(WSDataSourceConnectionProvider.class);

    public void configure(Properties props) throws HibernateException {

        String jndiName = props.getProperty(Environment.DATASOURCE);
        if (jndiName == null) {
            String msg = "datasource JNDI name was not specified by property "
                    + Environment.DATASOURCE;
            log.fatal(msg);
            throw new HibernateException(msg);
        }

        user = props.getProperty(Environment.USER);
        pass = props.getProperty(Environment.PASS);

        String i = props.getProperty(Environment.ISOLATION);
        if (i == null) {
            isolation = null;
        } else {
            isolation = new Integer(i);
            log.info("JDBC isolation level: "
                    + Environment.isolationLevelToString(isolation.intValue()));
        }

        try {
            ds = (WSDataSource) NamingHelper.getInitialContext(props).lookup(
                    jndiName);
        } catch (Exception e) {
            log.fatal("Could not find datasource: " + jndiName, e);
            throw new HibernateException("Could not find datasource", e);
        }
        if (ds == null)
            throw new HibernateException("Could not find datasource: "
                    + jndiName);
        log.info("Using datasource: " + jndiName);
    }

    public Connection getConnection() throws SQLException {
        if (log.isDebugEnabled()) {
            log.debug("getConnection()");
        }
        Connection connection = ds.getConnection(createJDBCConnectionSpec());

        if (log.isDebugEnabled()) {
            if (connection != null) {
                log.debug("Returning connection, System.identityHashCode="
                        + System.identityHashCode(connection));
                log.debug("Connection=" + connection);
                log.debug("Shareable=" + WSCallHelper.isShareable(connection));
                log.debug("Class=" + connection.getClass());
                Connection nativeConnection = (Connection) WSJdbcUtil
                        .getNativeConnection((WSJdbcConnection) connection);
                log.debug("Native connection=" + nativeConnection);
                log.debug("Native connection, System.identityHashCode="
                        + System.identityHashCode(nativeConnection)
                        + ", class=" + nativeConnection.getClass());
            } else {
                log.debug("Returning null");
            }
        }
        return connection;
    }

    public void closeConnection(Connection conn) throws SQLException {
        conn.close();
    }

    public void close() {
    }

    protected JDBCConnectionSpec createJDBCConnectionSpec() {
        JDBCConnectionSpec connSpec = WSRRAFactory.createJDBCConnectionSpec();

        // 设置事称隔离级别
        if (isolation != null) {
            connSpec.setTransactionIsolation(isolation);
        }

        if (user != null || pass != null) {
            connSpec.setUserName(user);
            connSpec.setPassword(pass);
        }
        return connSpec;
    }
}

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package com.unmi.db;

import java.sql.Connection;

import java.sql.SQLException;

import java.util.Properties;

import org.apache.log4j.Logger;

import org.hibernate.HibernateException;

import org.hibernate.cfg.Environment;

import org.hibernate.connection.ConnectionProvider;

import org.hibernate.util.NamingHelper;

import com.ibm.websphere.rsadapter.JDBCConnectionSpec;

import com.ibm.websphere.rsadapter.WSCallHelper;

import com.ibm.websphere.rsadapter.WSDataSource;

import com.ibm.websphere.rsadapter.WSRRAFactory;

import com.ibm.ws.rsadapter.jdbc.WSJdbcConnection;

import com.ibm.ws.rsadapter.jdbc.WSJdbcUtil;

/**

* ConnectionProvider implementation that implements WSDataSource specific

* Transaction Isolation level settings for the connection. Modified from the

* original DatasourceConnectionProvider class by Lari Hotari

public class WSDataSourceConnectionProvider implements ConnectionProvider {

public boolean supportsAggressiveRelease() {

return false;

}

private WSDataSource ds;

private String user;

private String pass;

private Integer isolation;

private static final Logger log = Logger

.getLogger(WSDataSourceConnectionProvider.class);

public void configure(Properties props) throws HibernateException {

String jndiName = props.getProperty(Environment.DATASOURCE);

if (jndiName == null) {

String msg = "datasource JNDI name was not specified by property "

+ Environment.DATASOURCE;

log.fatal(msg);

throw new HibernateException(msg);

}

user = props.getProperty(Environment.USER);

pass = props.getProperty(Environment.PASS);

String i = props.getProperty(Environment.ISOLATION);

if (i == null) {

isolation = null;

} else {

isolation = new Integer(i);

log.info("JDBC isolation level: "

+ Environment.isolationLevelToString(isolation.intValue()));

}

try {

ds = (WSDataSource) NamingHelper.getInitialContext(props).lookup(

jndiName);

} catch (Exception e) {

log.fatal("Could not find datasource: " + jndiName, e);

throw new HibernateException("Could not find datasource", e);

}

if (ds == null)

throw new HibernateException("Could not find datasource: "

+ jndiName);

log.info("Using datasource: " + jndiName);

}

public Connection getConnection() throws SQLException {

if (log.isDebugEnabled()) {

log.debug("getConnection()");

}

Connection connection = ds.getConnection(createJDBCConnectionSpec());

if (log.isDebugEnabled()) {

if (connection != null) {

log.debug("Returning connection, System.identityHashCode="

+ System.identityHashCode(connection));

log.debug("Connection=" + connection);

log.debug("Shareable=" + WSCallHelper.isShareable(connection));

log.debug("Class=" + connection.getClass());

Connection nativeConnection = (Connection) WSJdbcUtil

.getNativeConnection((WSJdbcConnection) connection);

log.debug("Native connection=" + nativeConnection);

log.debug("Native connection, System.identityHashCode="

+ System.identityHashCode(nativeConnection)

+ ", class=" + nativeConnection.getClass());

} else {

log.debug("Returning null");

}

return connection;

}

public void closeConnection(Connection conn) throws SQLException {

conn.close();

}

public void close() {

}

protected JDBCConnectionSpec createJDBCConnectionSpec() {

JDBCConnectionSpec connSpec = WSRRAFactory.createJDBCConnectionSpec();

// 设置事称隔离级别

if (isolation != null) {

connSpec.setTransactionIsolation(isolation);

}

if (user != null || pass != null) {

connSpec.setUserName(user);

connSpec.setPassword(pass);

}

return connSpec;

}

以上代码中类 WSRRAFactory、JDBCConnectionSpec 用到了 $WAS_HOME/lib/rsaexternal.jar；类WSJdbcConnection、WSJdbcUtil 用到了 $WAS_HOME/lib/rsadapterspi.jar，所以需要在编译时 $WAS_HOME/lib　中两那两个包引用进来。

同时，在 hibernate.cfg.xml 中要有如下配置，记得在 WAS 还需配置相应的连接池 jdbc/unmiDs。

<property name="connection.datasource">jdbc/unmiDs</property>
<property name="dialect">org.hibernate.dialect.OracleDialect</property>

<property name="hibernate.connection.provider_class">
    com.unmi.db.WSDataSourceConnectionProvider
</property>

<property name="connection.username">user</property>
<property name="connection.password">password</property>

<property name="connection.datasource">jdbc/unmiDs</property>

<property name="dialect">org.hibernate.dialect.OracleDialect</property>

com.unmi.db.WSDataSourceConnectionProvider

</property>

<property name="connection.password">password</property>

文中又有链接提到 Sharing connections in WebSphere Application Server V5

大致说到的是，在WAS环境中Hibernate应用程序运行时可能一个事物使用的并非是同一个链接，无形中搞出个分布式事物来吧，具体情况和解决办法还有待细究，希望这个就是我想要的结果。

OK，明天再来分析上面那两篇文章吧，期望找到一个治本的解决方案。

好像与现今使用的C3P0连接池也有关系，有建议说换成最近新版的

文中 c3p0 problem 也有提到把 maxStatements 和 maxStatementsPerConnection 设置为零
c3p0.maxStatements=0
c3p0.maxStatementsPerConnection=0

本文链接 https://yanbin.blog/hibernate-was-dead-lock/, 来自隔叶黄莺 Yanbin Blog

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