Hello I been experiencing a load of problems executing queries in a task
queue running on a backend.
The log goes like this:
Uncaught exception from servlet
com.google.apphosting.api.ApiProxy$ApiDeadlineExceededException: The API call
datastore_v3.RunQuery() took too long to respond and was cancelled.
at
com.google.apphosting.runtime.ApiProxyImpl$3.createDeadlineException(ApiProxyImpl.java:277)
at
com.google.appengine.tools.development.TimedFuture.get(TimedFuture.java:44)
at
com.google.common.util.concurrent.ForwardingFuture.get(ForwardingFuture.java:64)
at
com.google.appengine.api.utils.FutureWrapper.get(FutureWrapper.java:67)
at
com.google.appengine.api.utils.FutureWrapper.get(FutureWrapper.java:67)
at
com.google.appengine.api.datastore.FutureHelper.getInternal(FutureHelper.java:71)
at
com.google.appengine.api.datastore.FutureHelper.quietGet(FutureHelper.java:32)
at
com.google.appengine.api.datastore.QueryResultsSourceImpl.loadMoreEntities(QueryResultsSourceImpl.java:84)
at
com.google.appengine.api.datastore.QueryResultIteratorImpl.ensureLoaded(QueryResultIteratorImpl.java:169)
at
com.google.appengine.api.datastore.QueryResultIteratorImpl.nextList(QueryResultIteratorImpl.java:115)
at
com.google.appengine.api.datastore.LazyList.forceResolveToIndex(LazyList.java:107)
at
com.google.appengine.api.datastore.LazyList.resolveToIndex(LazyList.java:83)
at
com.google.appengine.api.datastore.LazyList.resolveToIndex(LazyList.java:65)
at
com.google.appengine.api.datastore.LazyList.isEmpty(LazyList.java:296)
at
com.google.appengine.api.datastore.PreparedQueryImpl.asSingleEntity(PreparedQueryImpl.java:81)*
at com.app.server.MyServlet.doGet(MyServlet.java:44)* at
javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at
org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
at
com.google.apphosting.utils.servlet.ParseBlobUploadFilter.doFilter(ParseBlobUploadFilter.java:97)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at
com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java:35)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at
com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at
org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
at
org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at
org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at
org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
at
com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java:249)
at
org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at
org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at
org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
at
com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:76)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at
com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:135)
at
com.google.apphosting.runtime.JavaRuntime.handleRequest(JavaRuntime.java:260)
at
com.google.apphosting.base.RuntimePb$EvaluationRuntime$2.handleRequest(RuntimePb.java:9805)
at com.google.net.rpc.impl.RpcUtil.runRpcInApplication(RpcUtil.java:422)
at com.google.net.rpc.impl.Server$RpcTask.runInContext(Server.java:579)
at
com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:449)
at com.google.tracing.TraceContext.runInContext(TraceContext.java:689)
at
com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:327)
at
com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:319)
at
com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:447)
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:636)
It points to the place in my app where a do a simple query by key like
this:
|41| Query qq = new Query("MyPersistentClass");
|42| qq.addFilter("__key__", Query.FilterOperator.EQUAL,
|43| KeyFactory.createKey("MyPersistentClass", "validKey"));
|44| Entity entity = datastore.prepare(qq).asSingleEntity();
The queue configuration in the queue.xml goes like this:
<queue>
<name>default</name>
<target>backend</target>
<rate>500/s</rate>
</queue>
The backend is configured as follows in the backend.xml file:
<backend name="task">
<class>B1</class>
<instances>1</instances>
<options>
<dynamic>true</dynamic>
</options>
</backend>
This behavior is across different task queues all running on top of the same
backend.
It's also intermittent, the query works as intended for some time and then
suddenly stops working an then comes back for all the queues at the same
time.
While the datastore queries are not working the backend instance shows 0%
CPU usage but keeps logging messages like the previously mentioned, when I
see that in the admin console I shut down the backend instance and when it
turns on again everything seems to work fine at that point.
I hope somebody could help.
Thanks in advance!
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