EclipseLink 并发异常
EclipseLink concurrency exception
在 glassfish 服务器无响应后查看一些日志时，我遇到了这个错误：
{{[#|2016-06-02T08:37:51.737+0200|WARNING|oracle-
glassfish3.1.2|org.restlet.Component.ServiceDispatcher|_ThreadID=165;_ThreadName=http-thread-pool-37860(5);|Exception or error caught in status service
javax.ejb.EJBException
at com.sun.ejb.containers.BaseContainer.processSystemException(BaseContainer.java:5236)
at com.sun.ejb.containers.BaseContainer.checkExceptionNoTx(BaseContainer.java:5065)
at com.sun.ejb.containers.BaseContainer.postInvokeTx(BaseContainer.java:4900)
at com.sun.ejb.containers.BaseContainer.postInvoke(BaseContainer.java:2046)
at com.sun.ejb.containers.BaseContainer.postInvoke(BaseContainer.java:1995)
at com.sun.ejb.containers.EJBLocalObjectInvocationHandler.invoke(EJBLocalObjectInvocationHandler.java:222)
at com.sun.ejb.containers.EJBLocalObjectInvocationHandlerDelegate.invoke(EJBLocalObjectInvocationHandlerDelegate.java:89)
at com.sun.proxy.$Proxy228.getKpiValuesFlat(Unknown Source)
at com.business.renderer.TopSuppliers.getData(TopSuppliers.java:174)
at com.business.renderer.TopSuppliers.getDataAsJSONTopSuppliers.java:179)
at com.business.renderer.TopSuppliers.render(TopSuppliers.java:107)
at com.ui.renderer.engine.AbstractRenderingEngine.render(AbstractRenderingEngine.java:140)
at com.services.filter.ContainerAdapter.represent(ContainerAdapter.java:311)
at org.restlet.resource.Resource.getRepresentation(Resource.java:259)
at org.restlet.resource.Resource.handleGet(Resource.java:425)
at org.restlet.resource.Finder.handle(Finder.java:470)
at org.restlet.routing.Filter.doHandle(Filter.java:156)
at org.restlet.routing.Filter.handle(Filter.java:203)
at org.restlet.routing.Router.doHandle(Router.java:497)
at org.restlet.routing.Router.handle(Router.java:737)
at com.servlets.ServiceDispatcher.handle(ServiceDispatcher.java:55)
at org.restlet.routing.Filter.doHandle(Filter.java:156)
at org.restlet.routing.Filter.handle(Filter.java:203)
at org.restlet.routing.Filter.doHandle(Filter.java:156)
at org.restlet.routing.Filter.handle(Filter.java:203)
at org.restlet.routing.Filter.doHandle(Filter.java:156)
at org.restlet.engine.application.StatusFilter.doHandle(StatusFilter.java:151)
at org.restlet.routing.Filter.handle(Filter.java:203)
at org.restlet.routing.Filter.doHandle(Filter.java:156)
at org.restlet.routing.Filter.handle(Filter.java:203)
at org.restlet.engine.ChainHelper.handle(ChainHelper.java:111)
at org.restlet.engine.application.ApplicationHelper.handle(ApplicationHelper.java:72)
at org.restlet.Application.handle(Application.java:388)
at org.restlet.routing.Filter.doHandle(Filter.java:156)
at org.restlet.routing.Filter.handle(Filter.java:203)
at org.restlet.routing.Router.doHandle(Router.java:497)
at org.restlet.routing.Router.handle(Router.java:737)
at org.restlet.routing.Filter.doHandle(Filter.java:156)
at org.restlet.routing.Filter.handle(Filter.java:203)
at org.restlet.routing.Router.doHandle(Router.java:497)
at org.restlet.routing.Router.handle(Router.java:737)
at org.restlet.routing.Filter.doHandle(Filter.java:156)
at org.restlet.routing.Filter.handle(Filter.java:203)
at org.restlet.engine.ChainHelper.handle(ChainHelper.java:111)
at org.restlet.Component.handle(Component.java:387)
at org.restlet.Server.handle(Server.java:488)
at org.restlet.engine.ServerHelper.handle(ServerHelper.java:71)
at org.restlet.engine.http.HttpServerHelper.handle(HttpServerHelper.java:150)
at org.restlet.ext.servlet.ServerServlet.service(ServerServlet.java:1037)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:770)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1554)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:339)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at com.jamonapi.JAMonFilter.doFilter(JAMonFilter.java:59)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:278)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:334)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:230)
at com.sun.enterprise.v3.services.impl.ContainerMapper$AdapterCallable.call(ContainerMapper.java:311)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:189)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:850)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:747)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1032)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:231)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:745)
Caused by: Exception [EclipseLink-2004] (Eclipse Persistence Services - 2.3.4.v20151027-346465e): org.eclipse.persistence.exceptions.ConcurrencyException
Exception Description: A signal was attempted before wait() on ConcurrencyManager. This normally means that an attempt was made to
commit or rollback a transaction before it was started, or to rollback a transaction twice.
at org.eclipse.persistence.exceptions.ConcurrencyException.signalAttemptedBeforeWait(ConcurrencyException.java:84)
at org.eclipse.persistence.internal.helper.ConcurrencyManager.releaseReadLock(ConcurrencyManager.java:489)
at org.eclipse.persistence.internal.identitymaps.CacheKey.releaseReadLock(CacheKey.java:386)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.cloneAndRegisterObject(UnitOfWorkImpl.java:1018)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.cloneAndRegisterObject(UnitOfWorkImpl.java:929)
at org.eclipse.persistence.internal.sessions.UnitOfWorkIdentityMapAccessor.getAndCloneCacheKeyFromParent(UnitOfWorkIdentityMapAccessor.java:181)
at org.eclipse.persistence.internal.sessions.UnitOfWorkIdentityMapAccessor.getFromIdentityMap(UnitOfWorkIdentityMapAccessor.java:120)
at org.eclipse.persistence.internal.sessions.IdentityMapAccessor.getFromIdentityMap(IdentityMapAccessor.java:380)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.registerExistingObject(UnitOfWorkImpl.java:3899)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.registerExistingObject(UnitOfWorkImpl.java:3854)
at org.eclipse.persistence.mappings.CollectionMapping.buildElementUnitOfWorkClone(CollectionMapping.java:267)
at org.eclipse.persistence.mappings.CollectionMapping.buildElementClone(CollectionMapping.java:279)
at org.eclipse.persistence.internal.queries.ContainerPolicy.addNextValueFromIteratorInto(ContainerPolicy.java:213)
at org.eclipse.persistence.mappings.CollectionMapping.buildCloneForPartObject(CollectionMapping.java:205)
at org.eclipse.persistence.internal.indirection.UnitOfWorkQueryValueHolder.buildCloneFor(UnitOfWorkQueryValueHolder.java:51)
at org.eclipse.persistence.internal.indirection.UnitOfWorkValueHolder.instantiateImpl(UnitOfWorkValueHolder.java:161)
at org.eclipse.persistence.internal.indirection.UnitOfWorkValueHolder.instantiate(UnitOfWorkValueHolder.java:222)
at org.eclipse.persistence.internal.indirection.DatabaseValueHolder.getValue(DatabaseValueHolder.java:88)
at org.eclipse.persistence.indirection.IndirectList.buildDelegate(IndirectList.java:244)
at org.eclipse.persistence.indirection.IndirectList.getDelegate(IndirectList.java:414)
at org.eclipse.persistence.indirection.IndirectList.<init>(IndirectList.java:542)
at org.eclipse.persistence.indirection.IndirectList.listIterator(IndirectList.java:541)
at org.eclipse.persistence.indirection.IndirectList.iterator(IndirectList.java:505)
at com.business.frontend.facade.impl.FrontEndBFBean.combineAllContainerKpis(FrontEndBFBean.java:515)
at com.business.frontend.facade.impl.FrontEndBFBean.getKpiValuesFlat(FrontEndBFBean.java:405)
at sun.reflect.GeneratedMethodAccessor237.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.glassfish.ejb.security.application.EJBSecurityManager.runMethod(EJBSecurityManager.java:1052)
at org.glassfish.ejb.security.application.EJBSecurityManager.invoke(EJBSecurityManager.java:1124)
at com.sun.ejb.containers.BaseContainer.invokeBeanMethod(BaseContainer.java:5409)
at com.sun.ejb.EjbInvocation.invokeBeanMethod(EjbInvocation.java:619)
at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:800)
at com.sun.ejb.EjbInvocation.proceed(EjbInvocation.java:571)
at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.doAround(SystemInterceptorProxy.java:162)
at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.aroundInvoke(SystemInterceptorProxy.java:144)
at sun.reflect.GeneratedMethodAccessor170.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.sun.ejb.containers.interceptors.AroundInvokeInterceptor.intercept(InterceptorManager.java:861)
at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:800)
at com.sun.ejb.containers.interceptors.InterceptorManager.intercept(InterceptorManager.java:370)
at com.sun.ejb.containers.BaseContainer.__intercept(BaseContainer.java:5381)
at com.sun.ejb.containers.BaseContainer.intercept(BaseContainer.java:5369)
at com.sun.ejb.containers.EJBLocalObjectInvocationHandler.invoke(EJBLocalObjectInvocationHandler.java:214)
... 75 more
经过进一步检查，我注意到以下几行：
_ThreadID=165;_ThreadName=http-thread-pool-37860(5);
和
Exception [EclipseLink-2004] (Eclipse Persistence Services - 2.3.4.v20151027-346465e)
我最初的想法是 HTTP 线程在等待 DB 调用完成时超时，然后 HTTP 线程中断了 EclipseLink，留下处于意外状态的 ConcurrencyManager（使用后实际上没有释放 DeferredLock） .我制作了一个小应用程序，通过调整服务器设置并长时间调用数据库并在数据库调用准备就绪之前终止 http 调用来测试我的假设，但这似乎并没有重现问题。还有就是异常发生时调用的方法没有使用任何一种JPA(ORM)，调用使用JDBC。大多数应用程序使用 EclipseLink 和 JPA，但不是这一部分。此外，应用程序使用大量数据库的情况并不少见。
所以我在想，除了描述性的 (This normally means that an attempt was made to
commit or rollback a transaction before it was started, or to rollback a transaction twice)，这个错误背后的原因可能是什么，我很确定代码没有做这样的事情。
所以一定是延迟加载有冲突，但我不知道什么情况会导致这个问题。
我不知道从哪里开始调查。欢迎任何想法:)
在这种错误情况下，并发异常的确切原因未知 - 我们只能看到一个线程通过触发实体上的惰性关系来访问上下文。这个实体是如何被读入的，以及在其他线程中发生了什么，这些线程可能也在使用这个实体被读取的 EntityManager（直接或间接地通过访问从它读取的实体）需要追踪，但通常可以避免。
EntityManagers 不能被多线程访问，因此不处理并发访问。从 EntityManagers 读入的实体有许多钩子到它们从中读取的上下文；这些挂钩允许惰性关系、更改跟踪等对应用程序透明发生。这样做的结果是这些实体也不能被同时访问——它们不应该在没有仔细考虑的情况下被应用程序缓存或传递。在许多情况下，应用程序最好让 JPA 处理缓存，并根据需要从上下文访问实体。
在 glassfish 服务器无响应后查看一些日志时，我遇到了这个错误：
{{[#|2016-06-02T08:37:51.737+0200|WARNING|oracle-
glassfish3.1.2|org.restlet.Component.ServiceDispatcher|_ThreadID=165;_ThreadName=http-thread-pool-37860(5);|Exception or error caught in status service
javax.ejb.EJBException
at com.sun.ejb.containers.BaseContainer.processSystemException(BaseContainer.java:5236)
at com.sun.ejb.containers.BaseContainer.checkExceptionNoTx(BaseContainer.java:5065)
at com.sun.ejb.containers.BaseContainer.postInvokeTx(BaseContainer.java:4900)
at com.sun.ejb.containers.BaseContainer.postInvoke(BaseContainer.java:2046)
at com.sun.ejb.containers.BaseContainer.postInvoke(BaseContainer.java:1995)
at com.sun.ejb.containers.EJBLocalObjectInvocationHandler.invoke(EJBLocalObjectInvocationHandler.java:222)
at com.sun.ejb.containers.EJBLocalObjectInvocationHandlerDelegate.invoke(EJBLocalObjectInvocationHandlerDelegate.java:89)
at com.sun.proxy.$Proxy228.getKpiValuesFlat(Unknown Source)
at com.business.renderer.TopSuppliers.getData(TopSuppliers.java:174)
at com.business.renderer.TopSuppliers.getDataAsJSONTopSuppliers.java:179)
at com.business.renderer.TopSuppliers.render(TopSuppliers.java:107)
at com.ui.renderer.engine.AbstractRenderingEngine.render(AbstractRenderingEngine.java:140)
at com.services.filter.ContainerAdapter.represent(ContainerAdapter.java:311)
at org.restlet.resource.Resource.getRepresentation(Resource.java:259)
at org.restlet.resource.Resource.handleGet(Resource.java:425)
at org.restlet.resource.Finder.handle(Finder.java:470)
at org.restlet.routing.Filter.doHandle(Filter.java:156)
at org.restlet.routing.Filter.handle(Filter.java:203)
at org.restlet.routing.Router.doHandle(Router.java:497)
at org.restlet.routing.Router.handle(Router.java:737)
at com.servlets.ServiceDispatcher.handle(ServiceDispatcher.java:55)
at org.restlet.routing.Filter.doHandle(Filter.java:156)
at org.restlet.routing.Filter.handle(Filter.java:203)
at org.restlet.routing.Filter.doHandle(Filter.java:156)
at org.restlet.routing.Filter.handle(Filter.java:203)
at org.restlet.routing.Filter.doHandle(Filter.java:156)
at org.restlet.engine.application.StatusFilter.doHandle(StatusFilter.java:151)
at org.restlet.routing.Filter.handle(Filter.java:203)
at org.restlet.routing.Filter.doHandle(Filter.java:156)
at org.restlet.routing.Filter.handle(Filter.java:203)
at org.restlet.engine.ChainHelper.handle(ChainHelper.java:111)
at org.restlet.engine.application.ApplicationHelper.handle(ApplicationHelper.java:72)
at org.restlet.Application.handle(Application.java:388)
at org.restlet.routing.Filter.doHandle(Filter.java:156)
at org.restlet.routing.Filter.handle(Filter.java:203)
at org.restlet.routing.Router.doHandle(Router.java:497)
at org.restlet.routing.Router.handle(Router.java:737)
at org.restlet.routing.Filter.doHandle(Filter.java:156)
at org.restlet.routing.Filter.handle(Filter.java:203)
at org.restlet.routing.Router.doHandle(Router.java:497)
at org.restlet.routing.Router.handle(Router.java:737)
at org.restlet.routing.Filter.doHandle(Filter.java:156)
at org.restlet.routing.Filter.handle(Filter.java:203)
at org.restlet.engine.ChainHelper.handle(ChainHelper.java:111)
at org.restlet.Component.handle(Component.java:387)
at org.restlet.Server.handle(Server.java:488)
at org.restlet.engine.ServerHelper.handle(ServerHelper.java:71)
at org.restlet.engine.http.HttpServerHelper.handle(HttpServerHelper.java:150)
at org.restlet.ext.servlet.ServerServlet.service(ServerServlet.java:1037)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:770)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1554)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:339)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at com.jamonapi.JAMonFilter.doFilter(JAMonFilter.java:59)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:278)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:334)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:230)
at com.sun.enterprise.v3.services.impl.ContainerMapper$AdapterCallable.call(ContainerMapper.java:311)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:189)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:850)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:747)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1032)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:231)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:745)
Caused by: Exception [EclipseLink-2004] (Eclipse Persistence Services - 2.3.4.v20151027-346465e): org.eclipse.persistence.exceptions.ConcurrencyException
Exception Description: A signal was attempted before wait() on ConcurrencyManager. This normally means that an attempt was made to
commit or rollback a transaction before it was started, or to rollback a transaction twice.
at org.eclipse.persistence.exceptions.ConcurrencyException.signalAttemptedBeforeWait(ConcurrencyException.java:84)
at org.eclipse.persistence.internal.helper.ConcurrencyManager.releaseReadLock(ConcurrencyManager.java:489)
at org.eclipse.persistence.internal.identitymaps.CacheKey.releaseReadLock(CacheKey.java:386)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.cloneAndRegisterObject(UnitOfWorkImpl.java:1018)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.cloneAndRegisterObject(UnitOfWorkImpl.java:929)
at org.eclipse.persistence.internal.sessions.UnitOfWorkIdentityMapAccessor.getAndCloneCacheKeyFromParent(UnitOfWorkIdentityMapAccessor.java:181)
at org.eclipse.persistence.internal.sessions.UnitOfWorkIdentityMapAccessor.getFromIdentityMap(UnitOfWorkIdentityMapAccessor.java:120)
at org.eclipse.persistence.internal.sessions.IdentityMapAccessor.getFromIdentityMap(IdentityMapAccessor.java:380)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.registerExistingObject(UnitOfWorkImpl.java:3899)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.registerExistingObject(UnitOfWorkImpl.java:3854)
at org.eclipse.persistence.mappings.CollectionMapping.buildElementUnitOfWorkClone(CollectionMapping.java:267)
at org.eclipse.persistence.mappings.CollectionMapping.buildElementClone(CollectionMapping.java:279)
at org.eclipse.persistence.internal.queries.ContainerPolicy.addNextValueFromIteratorInto(ContainerPolicy.java:213)
at org.eclipse.persistence.mappings.CollectionMapping.buildCloneForPartObject(CollectionMapping.java:205)
at org.eclipse.persistence.internal.indirection.UnitOfWorkQueryValueHolder.buildCloneFor(UnitOfWorkQueryValueHolder.java:51)
at org.eclipse.persistence.internal.indirection.UnitOfWorkValueHolder.instantiateImpl(UnitOfWorkValueHolder.java:161)
at org.eclipse.persistence.internal.indirection.UnitOfWorkValueHolder.instantiate(UnitOfWorkValueHolder.java:222)
at org.eclipse.persistence.internal.indirection.DatabaseValueHolder.getValue(DatabaseValueHolder.java:88)
at org.eclipse.persistence.indirection.IndirectList.buildDelegate(IndirectList.java:244)
at org.eclipse.persistence.indirection.IndirectList.getDelegate(IndirectList.java:414)
at org.eclipse.persistence.indirection.IndirectList.<init>(IndirectList.java:542)
at org.eclipse.persistence.indirection.IndirectList.listIterator(IndirectList.java:541)
at org.eclipse.persistence.indirection.IndirectList.iterator(IndirectList.java:505)
at com.business.frontend.facade.impl.FrontEndBFBean.combineAllContainerKpis(FrontEndBFBean.java:515)
at com.business.frontend.facade.impl.FrontEndBFBean.getKpiValuesFlat(FrontEndBFBean.java:405)
at sun.reflect.GeneratedMethodAccessor237.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.glassfish.ejb.security.application.EJBSecurityManager.runMethod(EJBSecurityManager.java:1052)
at org.glassfish.ejb.security.application.EJBSecurityManager.invoke(EJBSecurityManager.java:1124)
at com.sun.ejb.containers.BaseContainer.invokeBeanMethod(BaseContainer.java:5409)
at com.sun.ejb.EjbInvocation.invokeBeanMethod(EjbInvocation.java:619)
at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:800)
at com.sun.ejb.EjbInvocation.proceed(EjbInvocation.java:571)
at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.doAround(SystemInterceptorProxy.java:162)
at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.aroundInvoke(SystemInterceptorProxy.java:144)
at sun.reflect.GeneratedMethodAccessor170.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.sun.ejb.containers.interceptors.AroundInvokeInterceptor.intercept(InterceptorManager.java:861)
at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:800)
at com.sun.ejb.containers.interceptors.InterceptorManager.intercept(InterceptorManager.java:370)
at com.sun.ejb.containers.BaseContainer.__intercept(BaseContainer.java:5381)
at com.sun.ejb.containers.BaseContainer.intercept(BaseContainer.java:5369)
at com.sun.ejb.containers.EJBLocalObjectInvocationHandler.invoke(EJBLocalObjectInvocationHandler.java:214)
... 75 more
经过进一步检查，我注意到以下几行：
_ThreadID=165;_ThreadName=http-thread-pool-37860(5);
和
Exception [EclipseLink-2004] (Eclipse Persistence Services - 2.3.4.v20151027-346465e)
我最初的想法是 HTTP 线程在等待 DB 调用完成时超时，然后 HTTP 线程中断了 EclipseLink，留下处于意外状态的 ConcurrencyManager（使用后实际上没有释放 DeferredLock） .我制作了一个小应用程序，通过调整服务器设置并长时间调用数据库并在数据库调用准备就绪之前终止 http 调用来测试我的假设，但这似乎并没有重现问题。还有就是异常发生时调用的方法没有使用任何一种JPA(ORM)，调用使用JDBC。大多数应用程序使用 EclipseLink 和 JPA，但不是这一部分。此外，应用程序使用大量数据库的情况并不少见。
所以我在想，除了描述性的 (This normally means that an attempt was made to
commit or rollback a transaction before it was started, or to rollback a transaction twice)，这个错误背后的原因可能是什么，我很确定代码没有做这样的事情。
所以一定是延迟加载有冲突，但我不知道什么情况会导致这个问题。
我不知道从哪里开始调查。欢迎任何想法:)
在这种错误情况下，并发异常的确切原因未知 - 我们只能看到一个线程通过触发实体上的惰性关系来访问上下文。这个实体是如何被读入的，以及在其他线程中发生了什么，这些线程可能也在使用这个实体被读取的 EntityManager（直接或间接地通过访问从它读取的实体）需要追踪，但通常可以避免。
EntityManagers 不能被多线程访问，因此不处理并发访问。从 EntityManagers 读入的实体有许多钩子到它们从中读取的上下文；这些挂钩允许惰性关系、更改跟踪等对应用程序透明发生。这样做的结果是这些实体也不能被同时访问——它们不应该在没有仔细考虑的情况下被应用程序缓存或传递。在许多情况下，应用程序最好让 JPA 处理缓存，并根据需要从上下文访问实体。