java - 带有 MultiTenantConnectionProvider 的 Springboot Multi-Tenancy 总是抛出 org.apache.tomcat.jdbc.pool.PoolExhaustedException :

Question

我已经开始转换我现有的 Spring Boot(1.5.4.RELEASE) 应用程序以使用 Multi-Tenancy 功能。它是一个基于模式的 Multi-Tenancy 解决方案并且基于 mysql。正如下面建议的 hibernate 文档

https://docs.jboss.org/hibernate/orm/4.2/devguide/en-US/html/ch16.html

我已经实现了 MultiTenantConnectionProvider 和 CurrentTenantIdentifierResolver 接口(interface)并且工作正常。

package com.ifi.aws.tenant.config.hibernate;

import org.hibernate.HibernateException;
import org.hibernate.engine.jdbc.connections.spi.MultiTenantConnectionProvider;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import com.ifi.aws.tenant.entity.TenantContext;

import java.sql.Connection;
import java.sql.SQLException;

import javax.sql.DataSource;

@Component
public class MultiTenantConnectionProviderImpl implements MultiTenantConnectionProvider {

  private static final long serialVersionUID = 6246085840652870138L;

  @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 tenantIdentifier) throws SQLException {
  final Connection connection = getAnyConnection();
  try {
    connection.createStatement().execute( "USE " + tenantIdentifier );
  }
  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 " + TenantContext.DEFAULT_TENANT );
  }
  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;
}

}

---

package com.ifi.aws.tenant.config.hibernate;

import org.hibernate.context.spi.CurrentTenantIdentifierResolver;
import org.springframework.context.annotation.Configuration;

import com.ifi.aws.tenant.entity.TenantContext;

@Configuration
public class TenantIdentifierResolver implements CurrentTenantIdentifierResolver {

  @Override
  public String resolveCurrentTenantIdentifier() {


     String tenantId = TenantContext.getTenantSchema();

    //System.out.println("------------------ resolveCurrentTenantIdentifier = " + tenantId);
    if (tenantId != null) {
        return tenantId;
    }
    return TenantContext.DEFAULT_TENANT;
}
@Override
public boolean validateExistingCurrentSessions() {
    return true;
}
}

然后下面是我的 hibernate 配置

package com.ifi.aws.tenant.config.hibernate;

import org.hibernate.MultiTenancyStrategy;
import org.hibernate.cfg.Environment;
import org.hibernate.context.spi.CurrentTenantIdentifierResolver;
import 
org.hibernate.engine.jdbc.connections.spi.MultiTenantConnectionProvider;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.orm.jpa.JpaProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.orm.jpa.JpaVendorAdapter;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;

import java.util.HashMap;
import java.util.Map;

import javax.sql.DataSource;

@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.ifi.aws");
    em.setJpaVendorAdapter(jpaVendorAdapter());
    em.setJpaPropertyMap(properties);
   return em;
  }
}

但是有时系统会因以下错误而崩溃

Springboot Multi-tenant with MultiTenantConnectionProvider always throw org.apache.tomcat.jdbc.pool.PoolExhaustedException: [http-nio-8086-exec-2] Timeout: Pool empty. Unable to fetch a connection in 30 seconds, none available[size:100; busy:100; idle:0; lastwait:30000].

我在这个网站上做了一些阅读，并在下面的问题中发现了完全相同的问题。

Spring Boot: Apache derby pool empty. Unable to fetch a connection in 30 seconds Tomcat Connection Pool Exhasuted

他们建议的修复方法之一是添加以下配置

spring.datasource.tomcat.max-active=100
spring.datasource.tomcat.max-idle=8
spring.datasource.tomcat.min-idle=8

但我仍然遇到同样的错误，我调试了代码，发现它在每次执行数据库调用后都会关闭连接。你们有什么想法吗？

编辑

昨天我发现 API 根本没有关闭任何连接。我写了一个简单的实用程序来检查连接状态，如下所示

    @Autowired
private DataSource ds;

@Before("execution(* com.ifi.aws.*.dao.impl.springData.*.*(..))")
public void logBeforeConnection(JoinPoint jp) throws Throwable {
    logDataSourceInfos("Before", jp);
}

@After("execution(* com.ifi.aws.*.dao.impl.springData.*.*(..)) ")
public void logAfterConnection(JoinPoint jp) throws Throwable {
    logDataSourceInfos("After", jp);
}

public void logDataSourceInfos(final String time, final JoinPoint jp) {
    final String method = String.format("%s:%s", jp.getTarget().getClass().getName(), jp.getSignature().getName());
    logger.debug("--------------------------------------------------------------------------");
    logger.debug(String.format("%s %s: number of connections in use by the application (active): %d.", time, method, ds.getNumActive()));
    logger.debug(String.format("%s %s: the number of established but idle connections: %d.", time, method, ds.getNumIdle()));
    logger.debug(String.format("%s %s: number of threads waiting for a connection: %d.", time, method, ds.getWaitCount()));
}

这表明活跃连接在持续增长。

Before com.sun.proxy.$Proxy127:findOne: number of connections in use by the application (active): 21.
Before com.sun.proxy.$Proxy127:findOne: the number of established but idle connections: 0.
Before com.sun.proxy.$Proxy127:findOne: number of threads waiting for a connection: 0

-----------------

After com.sun.proxy.$Proxy127:findOne: number of connections in use by the application (active): 21.
After com.sun.proxy.$Proxy127:findOne: the number of established but idle connections: 0.
After com.sun.proxy.$Proxy127:findOne: number of threads waiting for a connection: 0.
o.h.e.t.i.TransactionImpl                : committing

-------------------

Before com.sun.proxy.$Proxy127:findOne: number of connections in use by the application (active): 21.
Before com.sun.proxy.$Proxy127:findOne: the number of established but idle connections: 0.
Before com.sun.proxy.$Proxy127:findOne: number of threads waiting for a connection: 0

-----------------

After com.sun.proxy.$Proxy127:findOne: number of connections in use by the application (active): 22.
After com.sun.proxy.$Proxy127:findOne: the number of established but idle connections: 0.
After com.sun.proxy.$Proxy127:findOne: number of threads waiting for a connection: 0.
o.h.e.t.i.TransactionImpl                : committing

-------------------

但是它在我的本地环境中非常好并且它正确地关闭了连接。我的测试环境部署在 AWS t2 windows 实例中，此 API 部署为 Spring Boot jar 文件，并在同一 t2 实例中安装了 MYSQL 服务器。我能看到的唯一区别是操作系统版本，可能是一些 MYSQL 服务器配置

编辑

我能够按照@xerx593 的说明解决问题

问题出在 supportsAggressiveRelease = true 上，我按照 @xerx593 的建议将其更改为 false。但是我仍然想知道它如何在我的本地环境而不是在测试环境中工作。根据 hibernate 文档，它说“此连接提供程序是否支持主动释放 JDBC 连接并稍后重新获取这些连接(如果需要)？”。测试环境和本地环境的配置相同，是否是操作系统版本或mysql配置的结果？

谢谢，凯伦

Answer 1

通过“蛮力”，我们发现问题出在 supportsAggressiveRelease 标志中，当设置 (= true) 时，在 DEV 环境中没有问题，但导致解决您的 AWS 实例上的问题。

解决方案:

@Override
public boolean supportsAggressiveRelease() {
   return false;//!
}

---

为什么这个环境不支持“积极的发布”，是在你的环境的配置/性质中......

• MultiTenantConnectionProvider javadoc
• AWS Documentation main page