title: Postgres connection has been closed error in Spring Boot
body: <p>I am running a Spring Boot application to create REST apis. Often I get an error saying that the database connection is closed, and after that I cannot make any calls to the application. I'm using Postgres DB. This is the complete stack trace:</p>
  
  <pre><code>org.springframework.transaction.CannotCreateTransactionException: Could not open JPA EntityManager for transaction; nested exception is javax.persistence.PersistenceException: org.hibernate.TransactionException: JDBC begin transaction failed: 
      at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:431)
      at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:373)
      at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:457)
      at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:276)
      at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
      at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
      at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:207)
      at com.sun.proxy.$Proxy91.findByUriMoniker(Unknown Source)
      at com.mypkg.businessobjects.OrderInfoBO.getOrderInfo(OrderInfoBO.java:76)
      at com.mypkg.controller.OrderInfoController.getOrderInfo(OrderInfoController.java:78)
      at sun.reflect.GeneratedMethodAccessor104.invoke(Unknown Source)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.lang.reflect.Method.invoke(Method.java:483)
      at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221)
      at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137)
      at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110)
      at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:777)
      at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:706)
      at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
      at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:943)
      at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:877)
      at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:966)
      at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:687)
      at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
      at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85)
      at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:130)
      at com.mypkg.config.CORSFilter.doFilter(CORSFilter.java:39)
      at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60)
      at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:132)
      at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
      at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
      at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:60)
      at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:132)
      at io.undertow.servlet.handlers.FilterHandler.handleRequest(FilterHandler.java:85)
      at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:61)
      at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
      at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:131)
      at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:56)
      at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
      at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:45)
      at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:63)
      at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:58)
      at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:70)
      at io.undertow.security.handlers.SecurityInitialHandler.handleRequest(SecurityInitialHandler.java:76)
      at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
      at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
      at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:261)
      at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:247)
      at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:76)
      at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:166)
      at io.undertow.server.Connectors.executeRootHandler(Connectors.java:197)
      at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:759)
      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
      at java.lang.Thread.run(Thread.java:745)
  Caused by: javax.persistence.PersistenceException: org.hibernate.TransactionException: JDBC begin transaction failed: 
      at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1763)
      at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1677)
      at org.hibernate.jpa.spi.AbstractEntityManagerImpl.throwPersistenceException(AbstractEntityManagerImpl.java:1771)
      at org.hibernate.jpa.internal.TransactionImpl.begin(TransactionImpl.java:64)
      at org.springframework.orm.jpa.vendor.HibernateJpaDialect.beginTransaction(HibernateJpaDialect.java:159)
      at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:380)
      ... 56 more
  Caused by: org.hibernate.TransactionException: JDBC begin transaction failed: 
      at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.doBegin(JdbcTransaction.java:76)
      at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.begin(AbstractTransactionImpl.java:162)
      at org.hibernate.internal.SessionImpl.beginTransaction(SessionImpl.java:1435)
      at org.hibernate.jpa.internal.TransactionImpl.begin(TransactionImpl.java:61)
      ... 58 more
  Caused by: org.postgresql.util.PSQLException: This connection has been closed.
      at org.postgresql.jdbc2.AbstractJdbc2Connection.checkClosed(AbstractJdbc2Connection.java:833)
      at org.postgresql.jdbc2.AbstractJdbc2Connection.getAutoCommit(AbstractJdbc2Connection.java:794)
      at sun.reflect.GeneratedMethodAccessor35.invoke(Unknown Source)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.lang.reflect.Method.invoke(Method.java:483)
      at org.apache.tomcat.jdbc.pool.ProxyConnection.invoke(ProxyConnection.java:126)
      at org.apache.tomcat.jdbc.pool.JdbcInterceptor.invoke(JdbcInterceptor.java:108)
      at org.apache.tomcat.jdbc.pool.DisposableConnectionFacade.invoke(DisposableConnectionFacade.java:81)
      at com.sun.proxy.$Proxy56.getAutoCommit(Unknown Source)
      at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.doBegin(JdbcTransaction.java:68)
      ... 61 more
  </code></pre>
  
  <p>When I restart the application, it goes away. I think this problem occurs when I restart my postgres DB. Why is this happening?</p>