GAE ConcurrentModificationException的同時commiting

我測試與JPA一個GAE應用程序部署在由SDK（版本1.7.1）提供碼頭本地主機。在每次提交時，框架都會引發一個ConcurrentModificationException異常，但該對象會保留在數據存儲區中。我做錯了什麼？ TNX預先GAE ConcurrentModificationException的同時commiting

應用服務引擎的API-1.0-SDK-1.7.1
DataNucleus將-API的JP-A-3.1.2
DataNucleus將核 - 3.1.2
datanucleus- AppEngine上-2.1.0-最終

Transaction failed to commit 
org.datanucleus.transaction.NucleusTransactionException: Transaction failed to commit 
    at org.datanucleus.TransactionImpl.commit(TransactionImpl.java:365) 
    at it.gustaff.core.PlaceRService.createPlace(PlaceRService.java:91) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) 
    at java.lang.reflect.Method.invoke(Method.java:597) 
    at com.google.appengine.tools.development.agent.runtime.Runtime.invoke(Runtime.java:115) 
    at com.sun.jersey.spi.container.JavaMethodInvokerFactory$1.invoke(JavaMethodInvokerFactory.java:60) 
    at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$TypeOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:185) 
    at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:75) 
    at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:288) 
    at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147) 
    at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:108) 
    at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147) 
    at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:84) 
    at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1469) 
    at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1400) 
    at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1349) 
    at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1339) 
    at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:416) 
    at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:537) 
    at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:708) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) 
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166) 
    at com.google.appengine.tools.development.HeaderVerificationFilter.doFilter(HeaderVerificationFilter.java:35) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:60) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:125) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at com.google.appengine.tools.development.BackendServersFilter.doFilter(BackendServersFilter.java:97) 
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388) 
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) 
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182) 
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765) 
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418) 
    at com.google.appengine.tools.development.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:94) 
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) 
    at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:370) 
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) 
    at org.mortbay.jetty.Server.handle(Server.java:326) 
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542) 
    at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:938) 
    at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:755) 
    at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218) 
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404) 
    at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409) 
    at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582) 
Caused by: java.util.ConcurrentModificationException 
    at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372) 
    at java.util.AbstractList$Itr.next(AbstractList.java:343) 
    at com.google.appengine.datanucleus.DatastoreConnectionFactoryImpl$DatastoreManagedConnection.close(DatastoreConnectionFactoryImpl.java:146) 
    at org.datanucleus.store.connection.ConnectionManagerImpl$2.transactionCommitted(ConnectionManagerImpl.java:296) 
    at org.datanucleus.TransactionImpl.internalPostCommit(TransactionImpl.java:577) 
    at org.datanucleus.TransactionImpl.commit(TransactionImpl.java:354) 
    ... 51 more

<persistence-unit name="appengine-transactions-optional"> 
    <provider>org.datanucleus.api.jpa.PersistenceProviderImpl</provider> 
    <class>it.gustaff.data.Place</class> 
    <properties> 
     <property name="datanucleus.NontransactionalRead" value="true"/> 
     <property name="datanucleus.NontransactionalWrite" value="true"/> 
     <property name="datanucleus.singletonEMFForName" value="true"/> 
     <property name="datanucleus.ConnectionURL" value="appengine"/> 
    </properties> 
</persistence-unit>

public Place createPlace(Place p){ 

    EntityManager entityManager = EMF.get().createEntityManager(); 
    entityManager.getTransaction().begin(); 
    //avoid to persist a Place with an Id already set 
    p.setId(null); 
    entityManager.persist(p); 
    ExecutionContext ec = (ExecutionContext) entityManager.getDelegate(); 
    ec.getTransaction().commit(); 
    entityManager.close(); 
    return p; 
}

@Entity 
public class Place { 

    private String name; 
    private String description; 
    private String address; 

    //omitted other getter/setter 

    private com.google.appengine.api.datastore.Key id; 

    @Id 
    @GeneratedValue(strategy = GenerationType.IDENTITY) 
    public Key getId() { 
     return id; 
    } 

    public void setId(Key id) { 
     this.id = id; 
    } 
}

來源

2012-10-24 Fabio Bonfante

這可能是完全無助於你，但如果它不是太晚了，我建議你改用客體。 –

@Riley Lark。我個人鼓勵用戶使用最適合他的應用的技術，而不是將自己的偏好強加於他;他比我或你更瞭解他的問題空間方式。計算器是幫助人們與具體問題 –

@RileyLark TNX爲你的小費，但是我需要保持「JPA簡介」爲最終從GAE –

你不要引用你的實體，什麼p.setId（空）在做什麼。這且不說東西，你可以嘗試（以找到真正的ConcurrentModificationException的事情）是（像）這

ExecutionContext ec = (ExecutionContext)entityManager.getDelegate(); 
ec.getTransaction().commit();

更換entityManager.getTransaction().commit()如果拋出一個NucleusTransactionException然後打印出堆棧跟蹤與事業，並將其添加對你的問題。原因是真正的問題在哪裏，如果它在GAE中存在問題，那麼它可以被修復，否則如果它在代碼中存在問題，那麼你知道它在哪裏。

來源

2012-10-25 05:31:26 DataNucleus

感謝您的關注，我已經添加了詳細信息...深入調試，如您所建議的，顯示問題存在，同時通知數據存儲區事務已完成。也許我的jar版本會有所幫助： * datanucleus-core-3.1.2 * datanucleus-appengine-2.1.0-final –

那麼你的GAE JPA插件版本是什麼？ – DataNucleus

datanucleus-api-jpa-3.1.2 –

GAE Con​​currentModificationException的同時commiting

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GAE ConcurrentModificationException的同時commiting