I get this set of exceptions from time to time when running my application

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Asked: May 19, 20262026-05-19T12:58:48+00:00 2026-05-19T12:58:48+00:00

I get this set of exceptions from time to time when running my application

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I get this set of exceptions from time to time when running my application in hosted mode in Eclipse. What’s strange about it, is that it doesn’t happen consistently. It will happen occasionally after recompiling and restarting the application. Restarting Eclipse will often clear it up (without a code change). does anyone have any thoughts on what might be going on here? Or even where I’d start looking?

[ERROR] javax.servlet.ServletContext log: Exception while dispatching incoming RPC call
com.google.gwt.user.server.rpc.UnexpectedException: Service method 'public abstract com.grgcomponents.coatl.client.auth.TwitterUser com.grgcomponents.coatl.client.auth.TwitterLoginService.getLoggedInUser(java.lang.String) throws java.lang.IllegalArgumentException' threw an unexpected exception: java.lang.UnsupportedOperationException
    at com.google.gwt.user.server.rpc.RPC.encodeResponseForFailure(RPC.java:378)
    at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:581)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:207)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:243)
    at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    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$CachedChain.doFilter(ServletHandler.java:1166)
    at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:58)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:122)
    at org.mortbay.jetty.servlet.ServletHandler$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.apphosting.utils.jetty.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:70)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:349)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:326)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
    at org.mortbay.jetty.HttpConnection$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.lang.UnsupportedOperationException
    at org.datanucleus.store.appengine.EntityUtils.getPropertyName(EntityUtils.java:62)
    at org.datanucleus.store.appengine.DatastoreFieldManager.getPropertyName(DatastoreFieldManager.java:1073)
    at org.datanucleus.store.appengine.DatastoreFieldManager.fetchObjectField(DatastoreFieldManager.java:309)
    at org.datanucleus.store.appengine.DatastoreFieldManager.fetchLongField(DatastoreFieldManager.java:429)
    at org.datanucleus.state.AbstractStateManager.replacingLongField(AbstractStateManager.java:1148)
    at com.grgcomponents.coatl.server.persisted.TwitterOAuthTokens.jdoReplaceField(TwitterOAuthTokens.java)
    at com.grgcomponents.coatl.server.persisted.TwitterOAuthTokens.jdoReplaceFields(TwitterOAuthTokens.java)
    at org.datanucleus.state.JDOStateManagerImpl.replaceFields(JDOStateManagerImpl.java:2772)
    at org.datanucleus.state.JDOStateManagerImpl.replaceFields(JDOStateManagerImpl.java:2791)
    at org.datanucleus.store.appengine.DatastorePersistenceHandler.fetchObject(DatastorePersistenceHandler.java:480)
    at org.datanucleus.state.JDOStateManagerImpl.validate(JDOStateManagerImpl.java:4263)
    at org.datanucleus.ObjectManagerImpl.findObject(ObjectManagerImpl.java:2444)
    at org.datanucleus.jpa.EntityManagerImpl.find(EntityManagerImpl.java:234)
    at org.datanucleus.store.appengine.jpa.DatastoreEntityManager.find(DatastoreEntityManager.java:56)
    at com.grgcomponents.coatl.server.auth.TwitterLoginServiceImpl.getCurrentUser(TwitterLoginServiceImpl.java:45)
    at com.grgcomponents.coatl.server.auth.TwitterLoginServiceImpl.getLoggedInUser(TwitterLoginServiceImpl.java:30)
    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:100)
    at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:562)
    ... 30 more


[ERROR] javax.servlet.ServletContext log: Exception while dispatching incoming RPC call
com.google.gwt.user.server.rpc.UnexpectedException: Service method 'public abstract java.lang.String com.grgcomponents.coatl.client.preferences.UserSettingsService.getSetting(java.lang.String,java.lang.String)' threw an unexpected exception: java.lang.UnsupportedOperationException
    at com.google.gwt.user.server.rpc.RPC.encodeResponseForFailure(RPC.java:378)
    at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:581)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:207)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:243)
    at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    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$CachedChain.doFilter(ServletHandler.java:1166)
    at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:58)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:122)
    at org.mortbay.jetty.servlet.ServletHandler$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.apphosting.utils.jetty.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:70)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:349)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:326)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
    at org.mortbay.jetty.HttpConnection$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.QueuedThreacom.google.gwt.user.client.rpc.StatusCodeException: 500 The call failed on the server; see server log for details
    at com.google.gwt.user.client.rpc.impl.RequestCallbackAdapter.onResponseReceived(RequestCallbackAdapter.java:192)
    at com.google.gwt.http.client.Request.fireOnResponseReceived(Request.java:287)
    at com.google.gwt.http.client.RequestBuilder$1.onReadyStateChange(RequestBuilder.java:395)
    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.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:157)
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:326)
    at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:207)
    at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:126)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269)
    at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
    at com.google.gwt.core.client.impl.Impl.apply(Impl.java)
    at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:214)
    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.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:157)
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:281)
    at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:531)
    at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:352)
    at java.lang.Thread.run(Thread.java:680)
dPool$PoolThread.run(QueuedThreadPool.java:582)
Caused by: java.lang.UnsupportedOperationException
    at org.datanucleus.store.appengine.EntityUtils.getPropertyName(EntityUtils.java:62)
    at org.datanucleus.store.appengine.DatastoreFieldManager.getPropertyName(DatastoreFieldManager.java:1073)
    at org.datanucleus.store.appengine.DatastoreFieldManager.fetchObjectField(DatastoreFieldManager.java:309)
    at org.datanucleus.store.appengine.DatastoreFieldManager.fetchLongField(DatastoreFieldManager.java:429)
    at org.datanucleus.state.AbstractStateManager.replacingLongField(AbstractStateManager.java:1148)
    at com.grgcomponents.coatl.server.persisted.TwitterOAuthTokens.jdoReplaceField(TwitterOAuthTokens.java)
    at com.grgcomponents.coatl.server.persisted.TwitterOAuthTokens.jdoReplaceFields(TwitterOAuthTokens.java)
    at org.datanucleus.state.JDOStateManagerImpl.replaceFields(JDOStateManagerImpl.java:2772)
    at org.datanucleus.state.JDOStateManagerImpl.replaceFields(JDOStateManagerImpl.java:2791)
    at org.datanucleus.store.appengine.DatastorePersistenceHandler.fetchObject(DatastorePersistenceHandler.java:480)
    at org.datanucleus.state.JDOStateManagerImpl.validate(JDOStateManagerImpl.java:4263)
    at org.datanucleus.ObjectManagerImpl.findObject(ObjectManagerImpl.java:2444)
    at org.datanucleus.jpa.EntityManagerImpl.find(EntityManagerImpl.java:234)
    at org.datanucleus.store.appengine.jpa.DatastoreEntityManager.find(DatastoreEntityManager.java:56)
    at com.grgcomponents.coatl.server.UserUtil.getTwitter(UserUtil.java:40)
    at com.grgcomponents.coatl.server.UserUtil.getUserSetting(UserUtil.java:62)
    at com.grgcomponents.coatl.server.preferences.UserSettingsServiceImpl.getSetting(UserSettingsServiceImpl.java:14)
    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:100)
    at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:562)
    ... 30 more

Here’s the class that I’m trying to persist:

package com.grgcomponents.coatl.server.persisted;

import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class TwitterOAuthTokens {
@Id
private String loginManagerCookie;

private String requestTokenKey;

private String requestTokenSecret;

private String userToken;

private String userTokenSecret;

private long lastUsed;

public String getLoginManagerCookie() {
    return loginManagerCookie;
}

public void setLoginManagerCookie(String loginManagerCookie) {
    this.loginManagerCookie = loginManagerCookie;
}

public String getUserToken() {
    return userToken;
}

public void setUserToken(String userToken) {
    this.userToken = userToken;
}

public String getUserTokenSecret() {
    return userTokenSecret;
}

public void setUserTokenSecret(String userTokenSecret) {
    this.userTokenSecret = userTokenSecret;
}

public String getRequestTokenKey() {
    return requestTokenKey;
}

public void setRequestTokenKey(String requestTokenKey) {
    this.requestTokenKey = requestTokenKey;
}

public String getRequestTokenSecret() {
    return requestTokenSecret;
}

public void setRequestTokenSecret(String requestTokenSecret) {
    this.requestTokenSecret = requestTokenSecret;
}

public long getLastUsed() {
    return lastUsed;
}

public void setLastUsed(long lastUsed) {
    this.lastUsed = lastUsed;
}

}

Here’s the call that actually appears to be failing (We enter in getTwitter( String ), and the failure occurs on the last line:

public static Twitter getTwitter( String loginManagerId )
{
    if( loginManagerId == null )
        return null;

    EntityManager em = CoatlEntityManagerFactory.getDefault()
            .createEntityManager();

    return getTwitter( loginManagerId, em );
}

public static Twitter getTwitter( String loginManagerId, EntityManager em )
{
    if( loginManagerId == null )
        return null;

    TwitterOAuthTokens storedTokens = em.find( TwitterOAuthTokens.class,
            loginManagerId );

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1 Answer

Editorial Team · Answer 1 · 2026-05-19T12:58:49+00:00

This is a sporadic error that happens from time to time on any persistable class, but moreso on ones that are used a lot in parallel. It happens in JDO and JPA, and it seems as though the local datastore locks a particular table / entity group and forgets to release it; thus causing all subsequent calls to ds operations to fail. I generally don’t have to restart eclipse; just stopping then starting the server tends to fix the problem, if not, a full refresh/clean build will do the trick.

The only real solution seems to be putting the get() or put() calls inside of a synchronized code block, which, in theory, ensures that only one thread at a time is accessing your entities. http://code.google.com/p/datanucleus-appengine/issues/detail?id=203

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