记录一次解决数据库连接池连接泄露BUG

1 BUG现象

系统并发请求，系统停滞无法使用，所有接口都是无法与后端进行交互的状态，系统并没有宕机

2 BUG的业务流程

插入分数方法涉及插入表ABCD 加了声明式事务
查询分数方法涉及表ABCD

controller() {

	@Transactional

	insertVo();

	selectById();

}

3 排查原因

因为代码不是我写的，一开始我就是怀疑是死锁导致的BUG，然后我用Jconsole，去检测一下死锁，并没有发现死锁，接下来我去Mysql看有没有死锁，结果也没有发现，然后我就懵了，jvm没有锁，mysql也没有锁且没有SQL在执行，为什么请求就会全注阻塞？

然后我去开始去看这个代码了，我发现他在控制层调用了两个业务层，通常我们只在控制层去做校验去调用一个service啊，然后我就继续看，insertVo插入了很多查询了很多，耗时3秒钟左右，selectById查询了一条SQL，这两个明面上的代码并没有什么加锁或什么飞天操作，想了半天搞不懂为什么。

然后我开始用排除法，把这些代码一一注释调试一下。我把insertVo注释掉，这个毋庸置疑，那只有一个简单的操作了，就查一表返回，这个绝对是没问题的，然后我把selectById注释掉，居然就好了？,selectById只有一条查询SQL啊也没有加锁，这个能解决但是肯定也不是这个原因。

然后我用druid监控到可使用连接数一直在占用，没有释放，我就去查druid配置，发现配置了

initial-size: 20 #初始大小

min-idle: 20 #最小空闲

max-active: 40 #最大链接

max-wait: 10000 #配置获取连接等待超时的时间

这个配置也没有毛病啊，没办法了我只能去看线程的具体信息了，查出来所有的线程池连接线程都是这样的

"pool-6-thread-10" #244 prio=5 os_prio=31 tid=0x00007fe94235f000 nid=0x22803 waiting on condition [0x00000003150ce000]

   java.lang.Thread.State: WAITING (parking)

	at sun.misc.Unsafe.park(Native Method)

	- parking to wait for  <0x00000006c109e090> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)

	at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)

	at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)

	at com.alibaba.druid.pool.DruidDataSource.takeLast(DruidDataSource.java:2315)

	at com.alibaba.druid.pool.DruidDataSource.getConnectionInternal(DruidDataSource.java:1781)

	at com.alibaba.druid.pool.DruidDataSource.getConnectionDirect(DruidDataSource.java:1494)

	at com.alibaba.druid.filter.FilterChainImpl.dataSource_connect(FilterChainImpl.java:5058)

	at com.alibaba.druid.filter.stat.StatFilter.dataSource_getConnection(StatFilter.java:704)

	at com.alibaba.druid.filter.FilterChainImpl.dataSource_connect(FilterChainImpl.java:5054)

	at com.alibaba.druid.filter.FilterAdapter.dataSource_getConnection(FilterAdapter.java:2759)

	at com.alibaba.druid.filter.FilterChainImpl.dataSource_connect(FilterChainImpl.java:5054)

	at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:1469)

	at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:1459)

	at com.alibaba.druid.pool.DruidDataSource.getConnection(DruidDataSource.java:83)

	at org.hibernate.engine.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:122)

	at org.hibernate.internal.NonContextualJdbcConnectionAccess.obtainConnection(NonContextualJdbcConnectionAccess.java:38)

	at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.acquireConnectionIfNeeded(LogicalConnectionManagedImpl.java:104)

	at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.getPhysicalConnection(LogicalConnectionManagedImpl.java:134)

	at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.getConnectionForTransactionManagement(LogicalConnectionManagedImpl.java:250)

	at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.begin(LogicalConnectionManagedImpl.java:258)

	at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.begin(JdbcResourceLocalTransactionCoordinatorImpl.java:246)

	at org.hibernate.engine.transaction.internal.TransactionImpl.begin(TransactionImpl.java:83)

	at org.springframework.orm.jpa.vendor.HibernateJpaDialect.beginTransaction(HibernateJpaDialect.java:184)

	at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:402)

	at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:376)

	at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:572)

	at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:360)

	at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:99)

	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)

	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:747)

	at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:95)

	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)

	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:747)

	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:689)

	at com.treach.platform.modules.service.impl.SysLogService$$EnhancerBySpringCGLIB$$36a85251.insert(<generated>)

	at com.treach.platform.log.factory.LogTaskFactory$2.run(LogTaskFactory.java:56)

	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)

	at java.util.concurrent.FutureTask.run(FutureTask.java:266)

	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)

	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)

	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)

	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)

	at java.lang.Thread.run(Thread.java:750)

   Locked ownable synchronizers:

	- <0x00000007741f0d68> (a java.util.concurrent.ThreadPoolExecutor$Worker)

是的，连接池连接一直被占用锁住了，为什么会被锁住呢？，也设置了连接等待超时时间啊，然后我怀疑是配置没有生效，写了个代码看看

public static void main(String[] args) throws SQLException {

        ConfigurableApplicationContext run = SpringApplication.run(NdCyApplication.class, args);

        DruidDataSource bean = run.getBean(DruidDataSource.class);

        int maxActive = bean.getMaxActive();

        long maxWait = bean.getMaxWait();

        log.info("数据库线程池与数据库最大链接数" + String.valueOf(maxActive));

        log.info("数据库线程池等待链接数超时时间"+String.valueOf(maxWait));

    }

结果：

数据库线程池与数据库最大链接数8

数据库线程池等待链接数超时时间-1

这个和配置的不一样啊，真的没有生效，然后我又去查为什么没有生效，原来配置类里面有个DataSoure

@Bean     //声明其为Bean实例

@Primary  //在同样的DataSource中，首先使用被标注的DataSource

@ConfigurationProperties(prefix = "spring.datasource")

public DruidDataSource dataSource(){

        DruidDataSource datasource = new DruidDataSource();

        List<Filter> filters = new ArrayList<>();

        filters.add(wallFilter);

        filters.add(new StatFilter());

        datasource.setProxyFilters(filters);

        return datasource;

}

我们applcation.yaml的配置被覆盖了，druid默认等待链接数超时时间-1，难怪长时间占用连接没有超时。

4 解决

把等待连接超时时间等设置上

@Bean     //声明其为Bean实例

@Primary  //在同样的DataSource中，首先使用被标注的DataSource

@ConfigurationProperties(prefix = "spring.datasource")

public DruidDataSource dataSource(){

        DruidDataSource datasource = new DruidDataSource();

        datasource.setInitialSize(20);

        datasource.setMaxActive(80);

        datasource.setMaxWait(5000);

        List<Filter> filters = new ArrayList<>();

        filters.add(wallFilter);

        filters.add(new StatFilter());

        datasource.setProxyFilters(filters);

        return datasource;

}

成功

5 不懂的点

为什么会出现不回收线程的情况按理来说现在没有SQL在执行，连接数不是会被回收吗回到线程池等待的线程就有连接了就能不卡死了为什么呢？