java - Spring JpaRepository findAll、Java 8 Stream、Connection 已被放弃

Question

我正在使用 Spring Boot 并尝试在 mu 存储库中执行 findAll 查询，该查询应返回结果流:

public interface MyThingRepository extends JpaRepository<MyThing, String> {
   Stream<MyThing> findAll();
}

public class MyScheduledJobRunner {

   @Autowired 
   private MyThingRepository myThingRepository;

   public void run() {
      try (Stream<MyThing> myThingsStream : myThingRepository.findAll()) {
        myThingsStream.forEach(myThing -> {
           // do some stuff
        });
        // myThingsStream.close(); // <- at one point even tried that, though the stream is wrapped in an auto-closing block. anyway, it did not help
       System.out.println("All my things processed.");
     }
     System.out.println("Exited the auto-closing block.");
   }
}

我得到的输出是:

All my things processed.
Exited the auto-closing block.
o.a.tomcat.jdbc.pool.ConnectionPool      : Connection has been abandoned PooledConnection[com.mysql.jdbc.JDBC4Connection@2865b7d5]:java.lang.Exception
|   at org.apache.tomcat.jdbc.pool.ConnectionPool.getThreadDump(ConnectionPool.java:1061)
...
at MyScheduledJobRunner.run(MyScheduledJobRunner:52) 

MyScheduledJobRunner:52 是:

try (Stream<MyThing> myThingsStream : myThingRepository.findAll()) {

根据文档，在 JpaRepositories 中使用 Streams 时，您应该始终在使用后关闭它们。由于它们实现了 AutoCloseable，因此您可以将 try 与资源 block 一起使用。 http://docs.spring.io/spring-data/jpa/docs/current/reference/html/#repositories.query-streaming

A Stream potentially wraps underlying data store specific resources and must therefore be closed after usage. You can either manually close the Stream using the close() method or by using a Java 7 try-with-resources block.

文档中甚至有一个示例，它的操作方式与我完全相同。因此，据我所知，我正在执行文档中所述的所有操作，但在操作后 30 秒我仍然收到异常。所以显然连接没有关闭并且处于挂起状态。这是为什么？我该如何克服这个问题？

我尝试过使用 Postgres 9.5 和 MariaDB 作为数据库。我正在使用最新的连接器/驱动程序和 Tomcat 连接池，它们是通过 Spring Boot 的属性配置的，如下所示:

spring:
  datasource:
    driverClassName: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost/mydb?useSSL=false
    username: user
    password: password
    initial-size: 10
    max-active: 100
    max-idle: 50
    min-idle: 10
    max-wait: 15000
    test-while-idle: true
    test-on-borrow: true
    validation-query: SELECT 1
    validation-query-timeout: 5
    validationInterval: 30000
    time-between-eviction-runs-millis: 30000
    min-evictable-idle-time-millis: 60000
    removeAbandonedTimeout: 60
    remove-abandoned: true
    log-abandoned: true

Answer 1

在池配置中您只需添加:“org.apache.tomcat.jdbc.pool.interceptor.ResetAbandonedTimer”