部署 Web 应用程序后出现“连接过多”错误

Question

我正在使用AbstractRoutingDataSource 在我的应用程序中创建多租户。我注意到，在从我的 IDE 重新部署了几次 webapp 之后，我最终得到了 MySQL 错误“连接太多”。 经过进一步调查，我发现当我运行MySQL命令show processlist;时，我看到每次部署后打开的连接量增加了10，这可能意味着连接池在某个地方仍然存在。 在我使用AbstractRoutingDataSource 之前，我使用了默认的spring 数据源配置（使用application.properties），它运行良好。

这里是多租户配置类：

import org.apache.commons.io.IOUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
import org.springframework.boot.autoconfigure.jdbc.DataSourceProperties;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;
import java.io.IOException;
import java.io.InputStream;
import java.util.*;
import java.util.stream.Collectors;

/**
 * Created by Alon Segal on 16/03/2017.
 */
@Configuration
public class MultitenantConfiguration {
    @Autowired
    private DataSourceProperties properties;

    /**
     * Defines the data source for the application
     *
     * @return
     */
    @Bean
    @ConfigurationProperties(
            prefix = "spring.datasource"
    )
    public DataSource dataSource() {

        //Creating datasources map "resolvedDataSources" here

        MultitenantDataSource dataSource = new MultitenantDataSource();
        dataSource.setDefaultTargetDataSource(defaultDataSource());
        dataSource.setTargetDataSources(resolvedDataSources);

        // Call this to finalize the initialization of the data source.
        dataSource.afterPropertiesSet();

        return dataSource;
    }

    /**
     * Creates the default data source for the application
     *
     * @return
     */
    private DataSource defaultDataSource() {
        .
        .
        .
    }
}

还有数据源类：

import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;

/**
 * Created by Alon Segal on 16/03/2017.
 */
public class MultitenantDataSource extends AbstractRoutingDataSource {

    @Override
    protected Object determineCurrentLookupKey() {
        return TenantContext.getCurrentTenant();
    }
}

我也尝试使用@Bean(destroyMethod = "close")，但AbstractRoutingDataSource 上没有定义关闭方法。

我到处搜索，但找不到答案。有人可以帮我了解是什么阻止了连接池在重新部署之间被释放吗？

提前致谢。

Answer 1

好的，所以我最终通过放弃使用 Spring 的 AbstractRoutingDataSource 并使用 Hibernate 的基于 this article 中的解决方案的多租户机制解决了这个问题。

长话短说

你需要做3个步骤：

第 1 步：创建 CurrentTenantIdentifierResolver

@Component
public class TenantIdentifierResolver implements CurrentTenantIdentifierResolver {

    @Override
    public String resolveCurrentTenantIdentifier() {
        String tenantId = TenantContext.getCurrentTenant();
        if (tenantId != null) {
            return tenantId;
        }
        return DEFAULT_TENANT_ID;
    }

    @Override
    public boolean validateExistingCurrentSessions() {
        return true;
    }
}

第 2 步：创建 MultiTenantConnectionProvider

@Component
public class MultiTenantConnectionProviderImpl implements MultiTenantConnectionProvider {

    @Autowired
    private DataSource dataSource;

    @Override
    public Connection getAnyConnection() throws SQLException {
        return dataSource.getConnection();
    }

    @Override
    public void releaseAnyConnection(Connection connection) throws SQLException {
        connection.close();
    }

    @Override
    public Connection getConnection(String tenantIdentifie) throws SQLException {
        String tenantIdentifier = TenantContext.getCurrentTenant();
        final Connection connection = getAnyConnection();
        try {
            if (tenantIdentifier != null) {
                connection.createStatement().execute("USE " + tenantIdentifier);
            } else {
                connection.createStatement().execute("USE " + DEFAULT_TENANT_ID);
            }
        }
        catch ( SQLException e ) {
            throw new HibernateException(
                    "Could not alter JDBC connection to specified schema [" + tenantIdentifier + "]",
                    e
            );
        }
        return connection;
    }

    @Override
    public void releaseConnection(String tenantIdentifier, Connection connection) throws SQLException {
        try {
            connection.createStatement().execute( "USE " + DEFAULT_TENANT_ID );
        }
        catch ( SQLException e ) {
            throw new HibernateException(
                    "Could not alter JDBC connection to specified schema [" + tenantIdentifier + "]",
                    e
            );
        }
        connection.close();
    }

    @SuppressWarnings("rawtypes")
    @Override
    public boolean isUnwrappableAs(Class unwrapType) {
        return false;
    }

    @Override
    public <T> T unwrap(Class<T> unwrapType) {
        return null;
    }

    @Override
    public boolean supportsAggressiveRelease() {
        return true;
    }

}

第 3 步：接线

@Configuration
public class HibernateConfig {

    @Autowired
    private JpaProperties jpaProperties;

    @Bean
    public JpaVendorAdapter jpaVendorAdapter() {
        return new HibernateJpaVendorAdapter();
    }

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(DataSource dataSource,
                                                                       MultiTenantConnectionProvider multiTenantConnectionProviderImpl,
                                                                       CurrentTenantIdentifierResolver currentTenantIdentifierResolverImpl) {
        Map<String, Object> properties = new HashMap<>();
        properties.putAll(jpaProperties.getHibernateProperties(dataSource));
        properties.put(Environment.MULTI_TENANT, MultiTenancyStrategy.SCHEMA);
        properties.put(Environment.MULTI_TENANT_CONNECTION_PROVIDER, multiTenantConnectionProviderImpl);
        properties.put(Environment.MULTI_TENANT_IDENTIFIER_RESOLVER, currentTenantIdentifierResolverImpl);

        LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
        em.setDataSource(dataSource);
        em.setPackagesToScan("com.autorni");
        em.setJpaVendorAdapter(jpaVendorAdapter());
        em.setJpaPropertyMap(properties);
        return em;
    }

}