So in the mean time I've been trying to understand the issue a bit better.

>From 3.1.0 to 3.2.0 the most notable difference is the HTTPClient package 
which introduces the PoolingHttpClientConnectionManager
( this is visibile in the stacktrace )

Since we run in Tomee ( Tomcat with EJB ) this is the cause of our 
problems:
https://stackoverflow.com/questions/27298746/using-poolinghttpclientconnectionmanager-in-ejb-container

After adding the following lines to our constructor:
HttpClient httpclient = HttpClients.custom().build();
HttpOp.setDefaultHttpClient(httpclient);

our problems are solved!

Is there some background information on this (or should there be some 
documentation aditions) 

Met Vriendelijke Groet / With Kind Regards
Bart van Leeuwen


twitter: @semanticfire
tel. +31(0)6-53182997
Netage B.V.
http://netage.nl
Esdoornstraat 3
3461ER Linschoten
The Netherlands




From:   Bart van Leeuwen <[email protected]>
To:     [email protected]
Date:   12-02-2019 22:49
Subject:        QueryExecution.exec stops working in Java Web Application



Hi, 

We have a web application which uses the following code to connect to a 
external endpoint 

QueryExecution exec  = 
QueryExecutionFactory.sparqlService(Config.getConfig("endpoint"), 
kroQuery); 
ResultSet objects = exec.execSelect(); 

This runs fine with Jena up to 3.1.0 

However with later versions we run into the issue that after 6 requests 
they don't return, upon killing the application ( or server ) this is 
visible on the console: 

==== 

WARNING - The web application [ROOT] is still processing a request that 
has yet to finish. This is very likely to create a memory leak. You can 
control the time allowed for requests to finish by using the unloadDelay 
attribute of the standard Context implementation. Stack trace of request 
processing thread: 
 sun.misc.Unsafe.park(Native Method) 
 java.util.concurrent.locks.LockSupport.park(LockSupport.java:175) 
 
java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
 

 org.apache.http.pool.PoolEntryFuture.await(PoolEntryFuture.java:138) 
 
org.apache.http.pool.AbstractConnPool.getPoolEntryBlocking(AbstractConnPool.java:306)
 

 
org.apache.http.pool.AbstractConnPool.access$000(AbstractConnPool.java:64) 

 
org.apache.http.pool.AbstractConnPool$2.getPoolEntry(AbstractConnPool.java:192) 

 
org.apache.http.pool.AbstractConnPool$2.getPoolEntry(AbstractConnPool.java:185) 

 org.apache.http.pool.PoolEntryFuture.get(PoolEntryFuture.java:107) 
 
org.apache.http.impl.conn.PoolingHttpClientConnectionManager.leaseConnection(PoolingHttpClientConnectionManager.java:276)
 

 
org.apache.http.impl.conn.PoolingHttpClientConnectionManager$1.get(PoolingHttpClientConnectionManager.java:263)
 

 
org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:190) 

 
org.apache.http.impl.client.cache.CachingExec.callBackend(CachingExec.java:592) 

 
org.apache.http.impl.client.cache.CachingExec.handleCacheMiss(CachingExec.java:356)
 

 
org.apache.http.impl.client.cache.CachingExec.execute(CachingExec.java:275) 

 
org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:184) 

 org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:88) 
 
org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:110) 

 
org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:184)
 

 
org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)
 

 
org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:55)
 

 org.apache.jena.riot.web.HttpOp.exec(HttpOp.java:1054) 
 org.apache.jena.riot.web.HttpOp.execHttpGet(HttpOp.java:281) 
 org.apache.jena.riot.web.HttpOp.execHttpGet(HttpOp.java:340) 
 org.apache.jena.sparql.engine.http.HttpQuery.execGet(HttpQuery.java:323) 
 org.apache.jena.sparql.engine.http.HttpQuery.exec(HttpQuery.java:282) 
 
org.apache.jena.sparql.engine.http.QueryEngineHTTP.execResultSetInner(QueryEngineHTTP.java:342)
 

 
org.apache.jena.sparql.engine.http.QueryEngineHTTP.execSelect(QueryEngineHTTP.java:334)
 

 webservice.KroService.getBlockAsJson(KroService.java:90) 
 sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
 
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 

 
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 

 java.lang.reflect.Method.invoke(Method.java:498) 
 
org.apache.openejb.server.cxf.rs.PojoInvoker.performInvocation(PojoInvoker.java:43)
 

 
org.apache.cxf.service.invoker.AbstractInvoker.invoke(AbstractInvoker.java:96) 

 org.apache.cxf.jaxrs.JAXRSInvoker.invoke(JAXRSInvoker.java:189) 
 org.apache.cxf.jaxrs.JAXRSInvoker.invoke(JAXRSInvoker.java:99) 
 
org.apache.openejb.server.cxf.rs.AutoJAXRSInvoker.invoke(AutoJAXRSInvoker.java:68)
 

 
org.apache.cxf.interceptor.ServiceInvokerInterceptor$1.run(ServiceInvokerInterceptor.java:59)
 

 
org.apache.cxf.interceptor.ServiceInvokerInterceptor.handleMessage(ServiceInvokerInterceptor.java:96)
 

 
org.apache.cxf.phase.PhaseInterceptorChain.doIntercept(PhaseInterceptorChain.java:308)
 

 
org.apache.cxf.transport.ChainInitiationObserver.onMessage(ChainInitiationObserver.java:121)
 

 
org.apache.cxf.transport.http.AbstractHTTPDestination.invoke(AbstractHTTPDestination.java:252)
 

 
org.apache.openejb.server.cxf.rs.CxfRsHttpListener.doInvoke(CxfRsHttpListener.java:251)
 

 
org.apache.tomee.webservices.CXFJAXRSFilter.doFilter(CXFJAXRSFilter.java:94) 

 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
 

 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
 

 org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) 
 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
 

 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
 

 
org.apache.shiro.web.servlet.AbstractShiroFilter.executeChain(AbstractShiroFilter.java:449)
 

 
org.apache.shiro.web.servlet.AbstractShiroFilter$1.call(AbstractShiroFilter.java:365)
 

 
org.apache.shiro.subject.support.SubjectCallable.doCall(SubjectCallable.java:90)
 

 
org.apache.shiro.subject.support.SubjectCallable.call(SubjectCallable.java:83) 

 
org.apache.shiro.subject.support.DelegatingSubject.execute(DelegatingSubject.java:383)
 

 
org.apache.shiro.web.servlet.AbstractShiroFilter.doFilterInternal(AbstractShiroFilter.java:362)
 

 
org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125)
 

 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
 

 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
 

 org.apache.catalina.filters.CorsFilter.handleNonCORS(CorsFilter.java:419) 

 org.apache.catalina.filters.CorsFilter.doFilter(CorsFilter.java:169) 
 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
 

 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165)
 

 
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
 

 
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:108)
 

 org.apache.tomee.catalina.OpenEJBValve.invoke(OpenEJBValve.java:44) 
 
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
 

 
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) 

 
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) 

 
org.apache.tomee.catalina.OpenEJBSecurityListener$RequestCapturer.invoke(OpenEJBSecurityListener.java:97)
 

 
org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
 

 
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
 

 
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349) 

 
org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:784) 

 
org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
 

 
org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:802)
 

 
org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1410)
 

 
org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) 

 
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) 

 
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) 

 
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
 

 java.lang.Thread.run(Thread.java:748) 

==== 

Any hint would be greatly appreciated. 

Met Vriendelijke Groet / With Kind Regards
Bart van Leeuwen 


twitter: @semanticfire 
tel. +31(0)6-53182997 
Netage B.V.
http://netage.nl 
Esdoornstraat 3 
3461ER Linschoten 
The Netherlands 


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