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• Google Chrome Add-on Naming

  - by Valentina Tatya

  Can add-ons have registered names in Google Chrome add-ons? I created a Youtube add-on and would like to add the Youtube term in my add-on name to better gain attention from users. I want to use it in the purpose of "fair use". Mozilla Add-ons are loose in restrictions about names but I see that there are not many add-ons containing Youtube or Facebook inside Chrome Market. Does that mean Chrome editors do not allow Registered terms inside the add-on names and should this be avoided?

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• System.getProperty("user.dir") cannot get my project root path ,but the path which my eclipse is located

  - by facebook-100005613813158

  As the title goes , I have class named GetException.java,inside it ,I read a xml file in a static code block like(Because this document is shared): static{ ... document = db.parse(new File(System.getProperty("user.dir")+"/src/exception/ExceptionCode.xml")); ... } To test if the file path is correct, I write a main function just inside GetException.java, it proves that the path is correct ,xml file can be read successfully. My project root dir is "/home/wuchang/workspace/MongodbI". But When this Class is loaded from other class,such as I called one of its static functions , it reports the error message: /home/mrs/??/eclipse/src/exception/ExceptionCode.xml (No such file or directory) /home/mrs/??/eclipse/ is actually my eclipse installation directory.So , I wander how System.getProperty("user.dir") returned the eclipse installation directory to me ,instead of my project root directory?

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• Global variable in a Linux shared library

  - by user3730495

  Suppose we have the following setup under Linux, .so library named "libcnt.so" and 3 user space apps: "app1", "app2", "app3". This library does 1 simple thing, it says to the app (app dynamically links the library at runtime) by how many apps it is already linked. Apps should have access to link counter. My knowledge in C and Linux is somewhat limited in this aspect, but as I understand this information should be stored in a global variable inside the shared object. Something like: in libcnt.h extern int cnt_loads; in libcnt.c int cnt_loads = 0; // where each linking increments this counter or something... So, my question is how it should be declared and/or defined inside .so library to guaranty that multiple apps from user space get the same instance of that variable counter?

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• Filling up the empty blocks when the player touches the safe zone again! using cocos2d

  - by user3445020

  Hi guys i am stuck with filling up the data of all the blocks which are empty like the ones in the image. As you can see there i have a pacman like object where i will be moving around. But when you are in the empty space where there are no Blue boxes available i should be able to add new blocks in the path of my pacman and when it touches any other blue boxes like in the below case if my pacman touches the top row of the blue box i should be able to fill all the empty boxed inside the border of the path created by pacman. For now i am using a 2d bool array to store all the filled boxed info like if there is a box inside i am making that cell in an array as true. But how to fill the area with blue boxes after player finishes his path ? Any help would be great thank you. More info about this problem is here: filling the empty spaces in a certain region in a grid using c++ Same problem

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• Connecting 2 PCs using USB-to-USB (male-male) cable

  - by Amirizzuan

  I found this while Googling around: http://www.hardwaresecrets.com/article/Connecting-Two-PCs-Using-a-USB-USB-Cable/248 But then, the solution given in the article is using Windows. Is there any Ubuntu equivalent to this? I would really love to SSH into my Ubuntu server via my Ubuntu laptop, just by connecting one end of the male USB to my laptop, and another end of the male USB to my server. I know I can always SSH into my server via the network, but then in this case of mine, there are cases the server is inside a secluded-secured network server room, and the only way for me to check things out is to go into the server room and open the keyboard console and monitor there. But, if I can just bring my laptop inside and connect to the USB there, then that would be cool. Any idea guys?

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• Is it possible to use the Raring install image as a package repo (like the old alternate CD)?

  - by jamadagni

  I use Kubuntu and recently upgraded to Raring directly from Precise. Until Precise, I always installed the OS using the alternate CD and not the desktop CD, because I could later on mount the image and use it as an offline package repo. For instance if I remove a package installed by the default installer and later I want to install it again, I can just install it from the ISO without needing to download it again. However, since Quantal the alternate CD no longer exists, so I am not sure how to set up the installed image as a local repo. I mean, doing find . -name "*.deb" inside the ISO tree after loopmounting it only shows a few packages like libc6 gcc and such and not the full set of packages that are actually installed -- I presume they are included in pre-installed form inside casper/filesystem.squashfs. Given this situation, is it or is it not possible to use the Raring install images as offline repos? If yes, how? Thank you!

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• Video Preview in Control Tooltip in WPF

  This article shows you about how to show video preview inside the controls tool tip.

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• JBoss 7.1.1 + Spring 3.1 + JPA 2 (Hibernate 3.6.8) > Cannot parse beans.xml

  - by Mashrur

  Trying to deploy a JSF 2 app with Spring 3.1 + JPA 2 (Hibernte 3.6.8) into JBoss 7.1.1 AS. The app was working fine on tomcat 7. Now, I have already added and changed some configurations. Added jboss-deployment-structure.xml <jboss-deployment-structure xmlns="urn:jboss:deployment-structure:1.1"> <deployment> <exclusions> <module name="org.apache.log4j" /> <module name="javax.faces.api" slot="main"/> <module name="com.sun.jsf-impl" slot="main"/> <module name="org.hibernate"/> <module name="org.javassist" /> <module name="javaee.api" /> <module name="org.hibernate.validator" /> <module name="org.jboss.as.web" /> <module name="org.jboss.logging" /> <module name="javax.persistence.api" /> <module name="org.jboss.interceptor" /> </exclusions> </deployment> </jboss-deployment-structure> 2. Inside web.xml added these lines: <persistence-unit-ref> <persistence-unit-ref-name>persistence/persistenceUnit</persistence-unit-ref-name> <persistence-unit-name>persistenceUnit</persistence-unit-name> </persistence-unit-ref> 3. Inside applicationContext.xml, changed bean definition for entityManagerFactory by adding this property <property name="persistenceXmlLocation" value="classpath*:META-INF/persistence.xml"/> Now, do I still need to do something more than these which is obvious to you? Because, while I am trying to deploy it from eclipse indigo SR2, getting this 14:10:32,046 INFO [org.jboss.modules] JBoss Modules version 1.1.1.GA 14:10:33,054 INFO [org.jboss.msc] JBoss MSC version 1.0.2.GA 14:10:33,200 INFO [org.jboss.as] JBAS015899: JBoss AS 7.1.1.Final "Brontes" starting 14:10:36,375 INFO [org.xnio] XNIO Version 3.0.3.GA 14:10:36,384 INFO [org.jboss.as.server] JBAS015888: Creating http management service using socket-binding (management-http) 14:10:36,432 INFO [org.xnio.nio] XNIO NIO Implementation Version 3.0.3.GA 14:10:36,462 INFO [org.jboss.remoting] JBoss Remoting version 3.2.3.GA 14:10:36,587 INFO [org.jboss.as.logging] JBAS011502: Removing bootstrap log handlers 14:10:36,714 INFO [org.jboss.as.security] (ServerService Thread Pool -- 44) JBAS013101: Activating Security Subsystem 14:10:36,735 INFO [org.jboss.as.naming] (MSC service thread 1-2) JBAS011802: Starting Naming Service 14:10:37,043 INFO [org.jboss.as.mail.extension] (MSC service thread 1-6) JBAS015400: Bound mail session [java:jboss/mail/Default] 14:10:37,208 INFO [org.jboss.as.connector] (MSC service thread 1-7) JBAS010408: Starting JCA Subsystem (JBoss IronJacamar 1.0.9.Final) 14:10:37,295 INFO [org.jboss.as.security] (MSC service thread 1-7) JBAS013100: Current PicketBox version=4.0.7.Final 14:10:37,740 INFO [org.jboss.as.connector.subsystems.datasources] (ServerService Thread Pool -- 27) JBAS010403: Deploying JDBC-compliant driver class org.h2.Driver (version 1.3) 14:10:38,792 INFO [org.jboss.ws.common.management.AbstractServerConfig] (MSC service thread 1-3) JBoss Web Services - Stack CXF Server 4.0.2.GA 14:10:38,833 INFO [org.apache.coyote.http11.Http11Protocol] (MSC service thread 1-2) Starting Coyote HTTP/1.1 on http-localhost-127.0.0.1-8080 14:10:39,534 INFO [org.jboss.as.server.deployment.scanner] (MSC service thread 1-1) JBAS015012: Started FileSystemDeploymentService for directory F:\work\softwares\Application Servers\JBoss\jboss-as-7.1.1.Final\jboss-as-7.1.1.Final\standalone\deployments 14:10:39,618 INFO [org.jboss.as.remoting] (MSC service thread 1-3) JBAS017100: Listening on localhost/127.0.0.1:4447 14:10:39,623 INFO [org.jboss.as.remoting] (MSC service thread 1-2) JBAS017100: Listening on /127.0.0.1:9999 14:10:39,698 INFO [org.jboss.as.server.deployment.scanner] (DeploymentScanner-threads - 1) JBAS015014: Re-attempting failed deployment treasury.war 14:10:39,706 INFO [org.jboss.as.server.deployment.scanner] (DeploymentScanner-threads - 1) JBAS015003: Found com.misl.treasury.ui.war in deployment directory. To trigger deployment create a file called com.misl.treasury.ui.war.dodeploy 14:10:40,105 INFO [org.jboss.as.connector.subsystems.datasources] (MSC service thread 1-2) JBAS010400: Bound data source [java:jboss/datasources/ExampleDS] 14:10:40,399 INFO [org.jboss.as.server.deployment] (MSC service thread 1-1) JBAS015876: Starting deployment of "com.misl.treasury.ui.war" 14:10:40,405 INFO [org.jboss.as.server.deployment] (MSC service thread 1-7) JBAS015876: Starting deployment of "treasury.war" 14:10:55,283 WARN [org.jboss.as.server.deployment] (MSC service thread 1-7) JBAS015893: Encountered invalid class name 'com.sun.faces.vendor.Tomcat6InjectionProvider:org.apache.catalina.util.DefaultAnnotationProcessor' for service type 'com.sun.faces.spi.injectionprovider' 14:10:55,289 WARN [org.jboss.as.server.deployment] (MSC service thread 1-7) JBAS015893: Encountered invalid class name 'com.sun.faces.vendor.Jetty6InjectionProvider:org.mortbay.jetty.plus.annotation.InjectionCollection' for service type 'com.sun.faces.spi.injectionprovider' 14:10:55,428 INFO [org.jboss.as.jpa] (MSC service thread 1-7) JBAS011401: Read persistence.xml for persistenceUnit 14:10:55,843 WARN [org.jboss.as.server.deployment] (MSC service thread 1-4) JBAS015893: Encountered invalid class name 'com.sun.faces.vendor.Tomcat6InjectionProvider:org.apache.catalina.util.DefaultAnnotationProcessor' for service type 'com.sun.faces.spi.injectionprovider' 14:10:55,849 WARN [org.jboss.as.server.deployment] (MSC service thread 1-4) JBAS015893: Encountered invalid class name 'com.sun.faces.vendor.Jetty6InjectionProvider:org.mortbay.jetty.plus.annotation.InjectionCollection' for service type 'com.sun.faces.spi.injectionprovider' 14:10:56,010 ERROR [org.jboss.msc.service.fail] (MSC service thread 1-2) MSC00001: Failed to start service jboss.deployment.unit."com.misl.treasury.ui.war".POST_MODULE: org.jboss.msc.service.StartException in service jboss.deployment.unit."com.misl.treasury.ui.war".POST_MODULE: Failed to process phase POST_MODULE of deployment "com.misl.treasury.ui.war" at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:119) [jboss-as-server-7.1.1.Final.jar:7.1.1.Final] at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1811) [jboss-msc-1.0.2.GA.jar:1.0.2.GA] at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1746) [jboss-msc-1.0.2.GA.jar:1.0.2.GA] at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) [rt.jar:1.6.0_23] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) [rt.jar:1.6.0_23] at java.lang.Thread.run(Thread.java:662) [rt.jar:1.6.0_23] Caused by: java.lang.NoClassDefFoundError: javax/servlet/ServletOutputStream at java.lang.Class.getDeclaredConstructors0(Native Method) [rt.jar:1.6.0_23] at java.lang.Class.privateGetDeclaredConstructors(Class.java:2389) [rt.jar:1.6.0_23] at java.lang.Class.getConstructor0(Class.java:2699) [rt.jar:1.6.0_23] at java.lang.Class.getConstructor(Class.java:1657) [rt.jar:1.6.0_23] at org.jboss.as.web.deployment.jsf.JsfManagedBeanProcessor.deploy(JsfManagedBeanProcessor.java:108) at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:113) [jboss-as-server-7.1.1.Final.jar:7.1.1.Final] ... 5 more Caused by: java.lang.ClassNotFoundException: javax.servlet.ServletOutputStream from [Module "deployment.com.misl.treasury.ui.war:main" from Service Module Loader] at org.jboss.modules.ModuleClassLoader.findClass(ModuleClassLoader.java:190) at org.jboss.modules.ConcurrentClassLoader.performLoadClassUnchecked(ConcurrentClassLoader.java:468) at org.jboss.modules.ConcurrentClassLoader.performLoadClassChecked(ConcurrentClassLoader.java:456) at org.jboss.modules.ConcurrentClassLoader.performLoadClassChecked(ConcurrentClassLoader.java:423) at org.jboss.modules.ConcurrentClassLoader.performLoadClass(ConcurrentClassLoader.java:398) at org.jboss.modules.ConcurrentClassLoader.loadClass(ConcurrentClassLoader.java:120) ... 11 more 14:10:56,628 ERROR [org.jboss.msc.service.fail] (MSC service thread 1-4) MSC00001: Failed to start service jboss.deployment.unit."treasury.war".PARSE: org.jboss.msc.service.StartException in service jboss.deployment.unit."treasury.war".PARSE: Failed to process phase PARSE of deployment "treasury.war" at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:119) [jboss-as-server-7.1.1.Final.jar:7.1.1.Final] at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1811) [jboss-msc-1.0.2.GA.jar:1.0.2.GA] at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1746) [jboss-msc-1.0.2.GA.jar:1.0.2.GA] at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) [rt.jar:1.6.0_23] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) [rt.jar:1.6.0_23] at java.lang.Thread.run(Thread.java:662) [rt.jar:1.6.0_23] Caused by: org.jboss.as.server.deployment.DeploymentUnitProcessingException: SAXException parsing vfs:/F:/work/softwares/Application Servers/JBoss/jboss-as-7.1.1.Final/jboss-as-7.1.1.Final/bin/content/treasury.war/WEB-INF/beans.xml at org.jboss.as.weld.deployment.BeansXmlParser.parse(BeansXmlParser.java:100) at org.jboss.as.weld.deployment.processors.BeansXmlProcessor.parseBeansXml(BeansXmlProcessor.java:133) at org.jboss.as.weld.deployment.processors.BeansXmlProcessor.deploy(BeansXmlProcessor.java:97) at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:113) [jboss-as-server-7.1.1.Final.jar:7.1.1.Final] ... 5 more Caused by: org.xml.sax.SAXParseException: Premature end of file. at org.apache.xerces.util.ErrorHandlerWrapper.createSAXParseException(ErrorHandlerWrapper.java:196) at org.apache.xerces.util.ErrorHandlerWrapper.fatalError(ErrorHandlerWrapper.java:175) at org.apache.xerces.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:394) at org.apache.xerces.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:322) at org.apache.xerces.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:281) at org.apache.xerces.impl.XMLScanner.reportFatalError(XMLScanner.java:1459) at org.apache.xerces.impl.XMLDocumentScannerImpl$PrologDispatcher.dispatch(XMLDocumentScannerImpl.java:903) at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:324) at org.apache.xerces.parsers.XML11Configuration.parse(XML11Configuration.java:845) at org.apache.xerces.parsers.XML11Configuration.parse(XML11Configuration.java:768) at org.apache.xerces.parsers.XMLParser.parse(XMLParser.java:108) at org.apache.xerces.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1196) at org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:555) at org.apache.xerces.jaxp.SAXParserImpl.parse(SAXParserImpl.java:289) at org.jboss.as.weld.deployment.BeansXmlParser.parse(BeansXmlParser.java:94) ... 8 more 14:10:56,670 INFO [org.jboss.as] (MSC service thread 1-1) JBAS015951: Admin console listening on http://127.0.0.1:9990 14:10:56,672 ERROR [org.jboss.as] (MSC service thread 1-1) JBAS015875: JBoss AS 7.1.1.Final "Brontes" started (with errors) in 25527ms - Started 143 of 222 services (2 services failed or missing dependencies, 76 services are passive or on-demand) 14:10:56,671 INFO [org.jboss.as.server] (DeploymentScanner-threads - 2) JBAS015871: Deploy of deployment "treasury.war" was rolled back with no failure message 14:10:56,679 INFO [org.jboss.as.server] (DeploymentScanner-threads - 2) JBAS015870: Deploy of deployment "com.misl.treasury.ui.war" was rolled back with failure message {"JBAS014671: Failed services" => {"jboss.deployment.unit.\"com.misl.treasury.ui.war\".POST_MODULE" => "org.jboss.msc.service.StartException in service jboss.deployment.unit.\"com.misl.treasury.ui.war\".POST_MODULE: Failed to process phase POST_MODULE of deployment \"com.misl.treasury.ui.war\""}} 14:10:56,851 INFO [org.jboss.as.server.deployment] (MSC service thread 1-8) JBAS015877: Stopped deployment com.misl.treasury.ui.war in 172ms 14:10:57,068 INFO [org.jboss.as.server.deployment] (MSC service thread 1-7) JBAS015877: Stopped deployment treasury.war in 395ms 14:10:57,070 INFO [org.jboss.as.controller] (DeploymentScanner-threads - 2) JBAS014774: Service status report JBAS014777: Services which failed to start: service jboss.deployment.unit."treasury.war".PARSE: org.jboss.msc.service.StartException in service jboss.deployment.unit."treasury.war".PARSE: Failed to process phase PARSE of deployment "treasury.war" service jboss.deployment.unit."com.misl.treasury.ui.war".POST_MODULE: org.jboss.msc.service.StartException in service jboss.deployment.unit."com.misl.treasury.ui.war".POST_MODULE: Failed to process phase POST_MODULE of deployment "com.misl.treasury.ui.war" 14:10:57,079 ERROR [org.jboss.as.server.deployment.scanner] (DeploymentScanner-threads - 1) {"JBAS014653: Composite operation failed and was rolled back. Steps that failed:" => {"Operation step-2" => {"JBAS014671: Failed services" => {"jboss.deployment.unit.\"com.misl.treasury.ui.war\".POST_MODULE" => "org.jboss.msc.service.StartException in service jboss.deployment.unit.\"com.misl.treasury.ui.war\".POST_MODULE: Failed to process phase POST_MODULE of deployment \"com.misl.treasury.ui.war\""}}}} 14:10:57,087 ERROR [org.jboss.as.server.deployment.scanner] (DeploymentScanner-threads - 1) JBAS014654: Composite operation was rolled back And by the way, JBOSS_HOME\modules\javax\api\main folder only contains a module.xml, no jars. Tried to add jboss-servlet-api_3.0_spec-1.0.0.Final.jar file in that directory and updated module.xml too. But, it shows a very long trail of stacktraces :) I have even removed beans.xml. No change. I have never tried JBoss before. Any help would be highly appreciated.

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• Self hosted WCF ServiceHost/WebServiceHost Concurrency/Peformance Design Options (.NET 3.5)

  - by Kyle

  So I'll be providing a few functions via a self hosted (in a WindowsService) WebServiceHost (not sure how to process HTTP GET/POST with ServiceHost), one of which may be called a large amount of the time. This function will also rely on a connection in the appdomain (hosted by the WindowsService so it can stay alive over multiple requests). I have the following concerns and would be oh so thankful for any input/thoughts/comments: Concurrent access - how does the WebServiceHost handle a bunch of concurrent requests. Are they queued and processes sequentially or are new instances of the contracts automagically created? WebServiceHost - WindowsService communication - I need some form of communication from the WebServiceHost to the hosting WindowsService for things like requesting a new session if one does not exist. Perhaps implementing a class which extends the WebServiceHost with events which the WindowsService subscribes to... (unless there is another way I can set off an event in the WindowsService when a request is made...) Multiple WebServiceHosts or Contracts - Would it give any real performance gain to be running multiple WebServiceHost instances in different threads (one per endpoint perhaps?) - A better understanding of the first point would probably help here. WSDL - I'm not sure why (probably just need to do more reading), but I'm not sure how to get the WebServiceHost base endpoint to respond with a WDSL document describing the available contract. Not required as all the operations will be done via GET requests which will not likely change, but it would be nice to have... That's about it for the moment ;) I've been reading a lot on WCF and wish I'd gotten into it long ago, but definitely still learning.

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• Circular reference with entity manager factory

  - by CodesLikeA_Mokey

  Every time I try and start my app, I get this error on startup: SEVERE: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor#0': Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'identityAccessAppConfig': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.package.identityaccess.identity.UserRepository com.package.identityaccess.IdentityAccessAppConfig.userRepository; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userRepository': Cannot create inner bean '(inner bean)' of type [org.springframework.orm.jpa.SharedEntityManagerCreator] while setting bean property 'entityManager'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#1': Cannot resolve reference to bean 'identityAccessEntityManagerFactory' while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'identityAccessEntityManagerFactory': Requested bean is currently in creation: Is there an unresolvable circular reference? at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:529) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:295) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:198) at org.springframework.context.support.AbstractApplicationContext.registerBeanPostProcessors(AbstractApplicationContext.java:741) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:464) at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:389) at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:294) at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:112) at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4797) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5291) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334) at java.util.concurrent.FutureTask.run(FutureTask.java:166) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:722) Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'identityAccessAppConfig': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.package.identityaccess.identity.UserRepository com.package.identityaccess.IdentityAccessAppConfig.userRepository; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userRepository': Cannot create inner bean '(inner bean)' of type [org.springframework.orm.jpa.SharedEntityManagerCreator] while setting bean property 'entityManager'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#1': Cannot resolve reference to bean 'identityAccessEntityManagerFactory' while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'identityAccessEntityManagerFactory': Requested bean is currently in creation: Is there an unresolvable circular reference? at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:288) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1116) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:295) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194) at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:353) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1025) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:921) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:487) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:295) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:198) at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansOfType(DefaultListableBeanFactory.java:438) at org.springframework.beans.factory.BeanFactoryUtils.beansOfTypeIncludingAncestors(BeanFactoryUtils.java:277) at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.detectPersistenceExceptionTranslators(PersistenceExceptionTranslationInterceptor.java:139) at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.<init>(PersistenceExceptionTranslationInterceptor.java:79) at org.springframework.dao.annotation.PersistenceExceptionTranslationAdvisor.<init>(PersistenceExceptionTranslationAdvisor.java:71) at org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor.setBeanFactory(PersistenceExceptionTranslationPostProcessor.java:85) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeAwareMethods(AbstractAutowireCapableBeanFactory.java:1502) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1470) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:521) ... 20 more Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.package.identityaccess.identity.UserRepository com.package.identityaccess.IdentityAccessAppConfig.userRepository; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userRepository': Cannot create inner bean '(inner bean)' of type [org.springframework.orm.jpa.SharedEntityManagerCreator] while setting bean property 'entityManager'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#1': Cannot resolve reference to bean 'identityAccessEntityManagerFactory' while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'identityAccessEntityManagerFactory': Requested bean is currently in creation: Is there an unresolvable circular reference? at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:514) at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:285) ... 45 more Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userRepository': Cannot create inner bean '(inner bean)' of type [org.springframework.orm.jpa.SharedEntityManagerCreator] while setting bean property 'entityManager'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#1': Cannot resolve reference to bean 'identityAccessEntityManagerFactory' while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'identityAccessEntityManagerFactory': Requested bean is currently in creation: Is there an unresolvable circular reference? at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveInnerBean(BeanDefinitionValueResolver.java:282) at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:126) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1387) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1128) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:295) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194) at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:912) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:855) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:770) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:486) ... 47 more Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#1': Cannot resolve reference to bean 'identityAccessEntityManagerFactory' while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'identityAccessEntityManagerFactory': Requested bean is currently in creation: Is there an unresolvable circular reference? at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:329) at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:107) at org.springframework.beans.factory.support.ConstructorResolver.resolveConstructorArguments(ConstructorResolver.java:615) at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:441) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1025) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:921) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:487) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458) at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveInnerBean(BeanDefinitionValueResolver.java:271) ... 60 more Caused by: org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'identityAccessEntityManagerFactory': Requested bean is currently in creation: Is there an unresolvable circular reference? at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.beforeSingletonCreation(DefaultSingletonBeanRegistry.java:327) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:217) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194) at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:323) I am new to configuring spring through java and have been spinning circles for days. I have my application which includes 2 separate modules. The identity-access module will handle user and access information and will have a datasource to an older database. The other module module2 will eventually have its own database. Here are the config files: application: @Configuration @EnableWebMvc @ComponentScan(basePackages = "com.package.myapp.web") @ImportResource({"classpath:com/package/appbase/appbase-context.xml"}) @Import(com.package.identityaccess.IdentityAccessAppConfig.class) public class IMSAppConfig extends WebMvcConfigurerAdapter { @Override public void addResourceHandlers(ResourceHandlerRegistry registry) { registry.addResourceHandler("/resources/**").addResourceLocations("ims/resources/"); } } identity-access: @Configuration @ComponentScan(basePackages = "com.package.identityaccess") @EnableJpaRepositories(entityManagerFactoryRef = "identityAccessEntityManagerFactory", value = "com.package.identityaccess") @EnableTransactionManagement public class IdentityAccessAppConfig { @Autowired UserRepository userRepository; @Bean public DataSource identityAccessDataSource() throws IOException, SQLException { return new SelfConfiguringBasicDataSource(System.getProperty("db_properties_path") + "/dev.oracle.properties", ""); } @Bean public Map<String, Object> identityAccessJpaProperties() { Map<String, Object> props = new HashMap<>(); props.put("eclipselink.weaving", "false"); props.put("eclipselink.target-database", OraclePlatform.class.getName()); return props; } @Bean public JpaVendorAdapter identityAccessJpaVendorAdapter() { EclipseLinkJpaVendorAdapter eclipseLinkJpaVendorAdapter = new EclipseLinkJpaVendorAdapter(); eclipseLinkJpaVendorAdapter.setDatabasePlatform(OraclePlatform.class.getName()); eclipseLinkJpaVendorAdapter.setGenerateDdl(false); eclipseLinkJpaVendorAdapter.setShowSql(true); return eclipseLinkJpaVendorAdapter; } @Bean public PlatformTransactionManager identityAccessTransactionManager() throws IOException, SQLException { JpaTransactionManager txManager = new JpaTransactionManager(); txManager.setEntityManagerFactory(identityAccessEntityManagerFactory().getObject()); return txManager; } @Bean public LocalContainerEntityManagerFactoryBean identityAccessEntityManagerFactory() throws IOException, SQLException { LocalContainerEntityManagerFactoryBean lef = new LocalContainerEntityManagerFactoryBean(); lef.setDataSource(identityAccessDataSource()); lef.setJpaPropertyMap(identityAccessJpaProperties()); lef.setJpaVendorAdapter(identityAccessJpaVendorAdapter()); lef.setPackagesToScan("com.package.identityaccess"); return lef; } @Bean public AuthenticationService authenticationService() { return new AuthenticationServiceImpl(userRepository); } } module2: @Configuration @ComponentScan(basePackages = "com.package.myapp.core") @EnableJpaRepositories("com.package.myapp.core.domain") @EnableTransactionManagement public class ModuleTwoAppConfig { @Bean public DataSource dataSource() { EmbeddedDatabaseBuilder embeddedDatabaseBuilder = new EmbeddedDatabaseBuilder(); embeddedDatabaseBuilder.setType(EmbeddedDatabaseType.HSQL); embeddedDatabaseBuilder.addScript("setup.sql"); return embeddedDatabaseBuilder.build(); } @Bean public Map<String, Object> jpaProperties() { Map<String, Object> props = new HashMap<>(); props.put("eclipselink.weaving", "false"); props.put("eclipselink.ddl-generation", "create-tables"); props.put("eclipselink.target-database", HSQLPlatform.class.getName()); return props; } @Bean public JpaVendorAdapter jpaVendorAdapter() { EclipseLinkJpaVendorAdapter eclipseLinkJpaVendorAdapter = new EclipseLinkJpaVendorAdapter(); eclipseLinkJpaVendorAdapter.setDatabasePlatform(HSQLPlatform.class.getName()); eclipseLinkJpaVendorAdapter.setGenerateDdl(true); eclipseLinkJpaVendorAdapter.setShowSql(true); return eclipseLinkJpaVendorAdapter; } @Bean public PlatformTransactionManager transactionManager() { JpaTransactionManager txManager = new JpaTransactionManager(); txManager.setEntityManagerFactory(entityManagerFactory().getObject()); return txManager; } @Bean public LocalContainerEntityManagerFactoryBean entityManagerFactory() { LocalContainerEntityManagerFactoryBean lef = new LocalContainerEntityManagerFactoryBean(); lef.setDataSource(dataSource()); lef.setJpaPropertyMap(jpaProperties()); lef.setJpaVendorAdapter(jpaVendorAdapter()); lef.setPackagesToScan("com.package.myapp.core.domain"); return lef; } } UserRepository (uses spring-data): public interface UserRepository extends JpaRepository<User, Long> { @Query("select u from User u where u.user_id = ?1") User findByUserId(String userId); } Can you see any problems with what I've done?

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• Java RMI timeout in callback

  - by sakra

  We are using Java RMI for communication. An RMI client passes a processing request and an object with a callback method to an RMI server. The server invokes the callback when it is done with processing. The setup is similar to the one described in RMI Callbacks. Occasionally we are getting a "read time out" exception in the server upon invoking the callback method. The callback thread stalls for about a minute before the exception is raised. java.rmi.ConnectIOException: error during JRMP connection establishment; nested exception is: java.net.SocketTimeoutException: Read timed out at sun.rmi.transport.tcp.TCPChannel.createConnection(TCPChannel.java:286) at sun.rmi.transport.tcp.TCPChannel.newConnection(TCPChannel.java:184) at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:110) at java.rmi.server.RemoteObjectInvocationHandler.invokeRemoteMethod(RemoteObjectInvocationHandler.java:178) at java.rmi.server.RemoteObjectInvocationHandler.invoke(RemoteObjectInvocationHandler.java:132) at $Proxy2.finished(Unknown Source) at com.unrisk.db.grid.GridTask.invokeCallback(com.unrisk.db.grid.GridTask:1292) at com.unrisk.db.grid.GridTask.invokeCallbacks(com.unrisk.db.grid.GridTask:1304) at com.unrisk.db.service.tasks.EquityMDTask.afterRun(com.unrisk.db.service.tasks.EquityMDTask:276) at com.unrisk.db.grid.GridTask.run(com.unrisk.db.grid.GridTask:720) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:619) Caused by: java.net.SocketTimeoutException: Read timed out at java.net.SocketInputStream.socketRead0(Native Method) at java.net.SocketInputStream.read(SocketInputStream.java:129) at java.io.BufferedInputStream.fill(BufferedInputStream.java:218) at java.io.BufferedInputStream.read(BufferedInputStream.java:237) at java.io.DataInputStream.readByte(DataInputStream.java:248) at sun.rmi.transport.tcp.TCPChannel.createConnection(TCPChannel.java:228) ... 12 more We are using Sun Java JDK 1.6.0_18 under Windows Server 2003 32-bit. Is it possible to work around the connection problems by tuning RMI related system properties?

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• Prepared transactions with Postgres 8.4.3 on CentOS

  - by peter

  I have set 'max_prepared_transactions' to 20 in the local postgres.config and yet the transaction fails with the following error trace (but only on Linux). Since in Windows the same code works seamlessly I am wandering if this isn't an issue of permission. What would be the solution? Thanks Peter 372300 [Atomikos:7] WARN atomikos - XA resource 'XADBMS': rollback for XID '3137332E3230332E3132362E3139302E746D30303030313030303037:3137332E3230332E3132362E3139302E746D31' raised -3: the XA resource detected an internal error org.postgresql.xa.PGXAException: Error rolling back prepared transaction at org.postgresql.xa.PGXAConnection.rollback(PGXAConnection.java:357) at com.atomikos.datasource.xa.XAResourceTransaction.rollback(XAResourceTransaction.java:873) at com.atomikos.icatch.imp.RollbackMessage.send(RollbackMessage.java:90) at com.atomikos.icatch.imp.PropagationMessage.submit(PropagationMessage.java:86) at com.atomikos.icatch.imp.Propagator$PropagatorThread.run(Propagator.java:62) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:651) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:676) at java.lang.Thread.run(Thread.java:595) Caused by: org.postgresql.util.PSQLException: ERROR: prepared transaction with identifier "1096044365_MTczLjIwMy4xMjYuMTkwLnRtMDAwMDEwMDAwNw==_MTczLjIwMy4xMjYuMTkwLnRtMQ==" does not exist at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2062) at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1795) at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:257) at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:479) at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:353) at org.postgresql.jdbc2.AbstractJdbc2Statement.executeUpdate(AbstractJdbc2Statement.java:299) at org.postgresql.xa.PGXAConnection.rollback(PGXAConnection.java:347)

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• when long polling, Why are my other requests taking so long?

  - by Pascal

  The client makes 2 concurrent requests. (1 which takes 60 seconds - long polling) and another which is NOT long polling - supposed to return right away. It does return right away when I'm not doing long polling. But as soon as I start doing long polling with the other thread, the other one takes forever to execute. Firebug shows that the request is waiting for 10-50 seconds. On the server, I profiled ALL requests from the moment the php script starts to the time it goes back to the client, and it shows that each one only took 300ms or less. This problem started about the same time I started doing long polling (with the other XHR requests). I'm using jquery for both requests. The server shows that it is under very light load. CPU and memory less then 2%. 8 processes running out of a pool of 15. (it doesn't seem to deviate much from that number 8, even when I run more ajax requests). I guess each process can run multiple ajax threads concurrently. I made sure to EXIT from all processes as soon as their done executing. I don't see how the process pool has run out, if there are still 7 unused processes listed under prstat -J. Also, the problem happens somewhat intermittently. Firefox should be able to handle 2 concurrent ajax requests. i dont get what the problem is.

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• Synchronizing ASP.NET MVC action methods with ReaderWriterLockSlim

  - by James D

  Any obvious issues/problems/gotchas with synchronizing access (in an ASP.NET MVC blogging engine) to a shared object model (NHibernate, but it could be anything) at the Controller/Action level via ReaderWriterLockSlim? (Assume the object model is very large and expensive to build per-request, so we need to share it among requests.) Here's how a typical "Read Post" action would look. Enter the read lock, do some work, exit the read lock. public ActionResult ReadPost(int id) { // ReaderWriterLockSlim allows multiple concurrent writes; this method // only blocks in the unlikely event that some other client is currently // writing to the model, which would only happen if a comment were being // submitted or a new post were being saved. _lock.EnterReadLock(); try { // Access the model, fetch the post with specificied id // Pseudocode, etc. Post p = TheObjectModel.GetPostByID(id); ActionResult ar = View(p); return ar; } finally { // Under all code paths, we must release the read lock _lock.ExitReadLock(); } } Meanwhile, if a user submits a comment or an author authors a new post, they're going to need write access to the model, which is done roughly like so: [AcceptVerbs(HttpVerbs.Post)] public ActionResult SaveComment(/* some posted data */) { // try/finally omitted for brevity _lock.EnterWriteLock(); // Save the comment to the DB, update the model to include the comment, etc. _lock.ExitWriteLock(); } Of course, this could also be done by tagging those action methods with some sort of "synchronized" attribute... but however you do it, my question is is this a bad idea? ps. ReaderWriterLockSlim is optimized for multiple concurrent reads, and only blocks if the write lock is held. Since writes are so infrequent (1000s or 10,000s or 100,000s of reads for every 1 write), and since they're of such a short duration, the effect is that the model is synchronized , and almost nobody ever locks, and if they do, it's not for very long.

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• SQL deadlock on delete then bulk insert

  - by StarLite

  I have an issue with a deadlock in SQL Server that I haven't been able to resolve. Basically I have a large number of concurrent connections (from many machines) that are executing transactions where they first delete a range of entries and then re-insert entries within the same range with a bulk insert. Essentially, the transaction looks like this BEGIN TRANSACTION T1 DELETE FROM [TableName] WITH( XLOCK HOLDLOCK ) WHERE [Id]=@Id AND [SubId]=@SubId INSERT BULK [TableName] ( [Id] Int , [SubId] Int , [Text] VarChar(max) COLLATE SQL_Latin1_General_CP1_CI_AS ) WITH(CHECK_CONSTRAINTS, FIRE_TRIGGERS) COMMIT TRANSACTION T1 The bulk insert only inserts items matching the Id and SubId of the deletion in the same transaction. Furthermore, these Id and SubId entries should never overlap. When I have enough concurrent transaction of this form, I start to see a significant number of deadlocks between these statements. I added the locking hints XLOCK HOLDLOCK to attempt to deal with the issue, but they don't seem to be helpling. The canonical deadlock graph for this error shows: Connection 1: Holds RangeX-X on PK_TableName Holds IX Page lock on the table Requesting X Page lock on the table Connection 2: Holds IX Page lock on the table Requests RangeX-X lock on the table What do I need to do in order to ensure that these deadlocks don't occur. I have been doing some reading on the RangeX-X locks and I'm not sure I fully understand what is going on with these. Do I have any options short of locking the entire table here?

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• Bluetooth connection. Problem with sony ericsson.

  - by Hugi

  I have bt client and server. Then i use method Connector.open, client connects to the port, but passed so that my server does not see them. Nokia for all normal, but with sony ericsson i have this problem. On bt adapter open one port (com 5). Listings Client /* * To change this template, choose Tools | Templates * and open the template in the editor. */ import java.util.Vector; import javax.bluetooth.*; import javax.microedition.midlet.*; import javax.microedition.lcdui.*; import javax.microedition.io.*; import java.io.*; /** * @author ????????????? */ public class Client extends MIDlet implements DiscoveryListener, CommandListener { private static Object lock=new Object(); private static Vector vecDevices=new Vector(); private ServiceRecord[] servRec = new ServiceRecord[INQUIRY_COMPLETED]; private Form form = new Form( "Search" ); private List voteList = new List( "Vote list", List.IMPLICIT ); private List vote = new List( "", List.EXCLUSIVE ); private RemoteDevice remoteDevice; private String connectionURL = null; protected int stopToken = 255; private Command select = null; public void startApp() { //view form Display.getDisplay(this).setCurrent(form); try { //device search print("Starting device inquiry..."); getAgent().startInquiry(DiscoveryAgent.GIAC, this); try { synchronized(lock){ lock.wait(); } }catch (InterruptedException e) { e.printStackTrace(); } //device count int deviceCount=vecDevices.size(); if(deviceCount <= 0) { print("No Devices Found ."); } else{ remoteDevice=(RemoteDevice)vecDevices.elementAt(0); print( "Server found" ); //create uuid UUID uuid = new UUID(0x1101); UUID uuids[] = new UUID[] { uuid }; //search service print( "Searching for service..." ); getAgent().searchServices(null,uuids,remoteDevice,this); } } catch( Exception e) { e.printStackTrace(); } } //if deivce discovered add to vecDevices public void deviceDiscovered(RemoteDevice btDevice, DeviceClass cod) { //add the device to the vector try { if(!vecDevices.contains(btDevice) && btDevice.getFriendlyName(true).equals("serverHugi")){ vecDevices.addElement(btDevice); } } catch( IOException e ) { } } public synchronized void servicesDiscovered(int transID, ServiceRecord[] servRecord) { //for each service create connection if( servRecord!=null && servRecord.length>0 ){ print( "Service found" ); connectionURL = servRecord[0].getConnectionURL(ServiceRecord.NOAUTHENTICATE_NOENCRYPT,false); //connectionURL = servRecord[0].getConnectionURL(ServiceRecord.AUTHENTICATE_NOENCRYPT,false); } if ( connectionURL != null ) { showVoteList(); } } public void serviceSearchCompleted(int transID, int respCode) { //print( "serviceSearchCompleted" ); synchronized(lock){ lock.notify(); } } //This callback method will be called when the device discovery is completed. public void inquiryCompleted(int discType) { synchronized(lock){ lock.notify(); } switch (discType) { case DiscoveryListener.INQUIRY_COMPLETED : print("INQUIRY_COMPLETED"); break; case DiscoveryListener.INQUIRY_TERMINATED : print("INQUIRY_TERMINATED"); break; case DiscoveryListener.INQUIRY_ERROR : print("INQUIRY_ERROR"); break; default : print("Unknown Response Code"); break; } } //add message at form public void print( String msg ) { form.append( msg ); form.append( "\n\n" ); } public void pauseApp() { } public void destroyApp(boolean unconditional) { } //get agent :))) private DiscoveryAgent getAgent() { try { return LocalDevice.getLocalDevice().getDiscoveryAgent(); } catch (BluetoothStateException e) { throw new Error(e.getMessage()); } } private synchronized String getMessage( final String send ) { StreamConnection stream = null; DataInputStream in = null; DataOutputStream out = null; String r = null; try { //open connection stream = (StreamConnection) Connector.open(connectionURL); in = stream.openDataInputStream(); out = stream.openDataOutputStream(); out.writeUTF( send ); out.flush(); r = in.readUTF(); print( r ); in.close(); out.close(); stream.close(); return r; } catch (IOException e) { } finally { if (stream != null) { try { stream.close(); } catch (IOException e) { } } return r; } } private synchronized void showVoteList() { String votes = getMessage( "c_getVotes" ); voteList.append( votes, null ); select = new Command( "Select", Command.OK, 4 ); voteList.addCommand( select ); voteList.setCommandListener( this ); Display.getDisplay(this).setCurrent(voteList); } private synchronized void showVote( int index ) { String title = getMessage( "c_getVote_"+index ); vote.setTitle( title ); vote.append( "Yes", null ); vote.append( "No", null ); vote.setCommandListener( this ); Display.getDisplay(this).setCurrent(vote); } public void commandAction( Command c, Displayable d ) { if ( c == select && d == voteList ) { int index = voteList.getSelectedIndex(); print( ""+index ); showVote( index ); } } } Use BlueCove in this program. Server /* * To change this template, choose Tools | Templates * and open the template in the editor. */ package javaapplication4; import java.io.*; import java.util.concurrent.locks.Lock; import java.util.concurrent.locks.ReentrantLock; import javax.bluetooth.*; import javax.microedition.io.*; import javaapplication4.Connect; /** * * @author ????????????? */ public class SampleSPPServer { protected static int endToken = 255; private static Lock lock=new ReentrantLock(); private static StreamConnection conn = null; private static StreamConnectionNotifier streamConnNotifier = null; private void startServer() throws IOException{ //Create a UUID for SPP UUID uuid = new UUID("1101", true); //Create the service url String connectionString = "btspp://localhost:" + uuid +";name=Sample SPP Server"; //open server url StreamConnectionNotifier streamConnNotifier = (StreamConnectionNotifier)Connector.open( connectionString ); while ( true ) { Connect ct = new Connect( streamConnNotifier.acceptAndOpen() ); ct.getMessage(); } } /** * @param args the command line arguments */ public static void main(String[] args) { //display local device address and name try { LocalDevice localDevice = LocalDevice.getLocalDevice(); localDevice.setDiscoverable(DiscoveryAgent.GIAC); System.out.println("Name: "+localDevice.getFriendlyName()); } catch( Throwable e ) { e.printStackTrace(); } SampleSPPServer sampleSPPServer=new SampleSPPServer(); try { //start server sampleSPPServer.startServer(); } catch( IOException e ) { e.printStackTrace(); } } } Connect /* * To change this template, choose Tools | Templates * and open the template in the editor. */ package javaapplication4; import java.io.*; import java.util.concurrent.locks.Lock; import java.util.concurrent.locks.ReentrantLock; import javax.bluetooth.*; import javax.microedition.io.*; /** * * @author ????????????? */ public class Connect { private static DataInputStream in = null; private static DataOutputStream out = null; private static StreamConnection connection = null; private static Lock lock=new ReentrantLock(); public Connect( StreamConnection conn ) { connection = conn; } public synchronized void getMessage( ) { Thread t = new Thread() { public void run() { try { in = connection.openDataInputStream(); out = connection.openDataOutputStream(); String r = in.readUTF(); System.out.println("read:" + r); if ( r.equals( "c_getVotes" ) ) { out.writeUTF( "vote1" ); out.flush(); } if ( r.equals( "c_getVote_0" ) ) { out.writeUTF( "Vote1" ); out.flush(); } out.close(); in.close(); } catch (Throwable e) { } finally { if (in != null) { try { in.close(); } catch (IOException e) { } } try { connection.close(); } catch( IOException e ) { } } } }; t.start(); } }

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• Apache with JBOSS using AJP (mod_jk) giving spikes in thread count.

  - by Beginner

  We used Apache with JBOSS for hosting our Application, but we found some issues related to thread handling of mod_jk. Our website comes under low traffic websites and has maximum 200-300 concurrent users during our website's peak activity time. As the traffic grows (not in terms of concurrent users, but in terms of cumulative requests which came to our server), the server stopped serving requests for long, although it didn't crash but could not serve the request till 20 mins. The JBOSS server console showed that 350 thread were busy on both servers although there was enough free memory say, more than 1-1.5 GB (2 servers for JBOSS were used which were 64 bits, 4 GB RAM allocated for JBOSS) In order to check the problem we were using JBOSS and Apache Web Consoles, and we were seeing that the thread were showing in S state for as long as minutes although our pages take around 4-5 seconds to be served. We took the thread dump and found that the threads were mostly in WAITING state which means that they were waiting indefinitely. These threads were not of our Application Classes but of AJP 8009 port. Could somebody help me in this, as somebody else might also got this issue and solved it somehow. In case any more information is required then let me know. Also is mod_proxy better than using mod_jk, or there are some other problems with mod_proxy which can be fatal for me if I switch to mod__proxy? The versions I used are as follows: Apache 2.0.52 JBOSS: 4.2.2 MOD_JK: 1.2.20 JDK: 1.6 Operating System: RHEL 4 Thanks for the help.

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• Send smtp mail in php with HTML page attach as a text

  - by Nirmal

  Hello All.... I have a requirement of sending mail using smtp server in php. Now I am able to send the mail using smtp for a plain text. but I have a requirement where I need to attach an HTML page, which includes set of images. Now for that I am trying the following code : <?php require_once "Mail.php"; $to = '[email protected]'; $from = '[email protected]'; $subject = $_POST['subject']; $body = $_POST['message']; $fileatt = $_FILES['fileatt']['tmp_name']; $fileatt_type = $_FILES['fileatt']['type']; $fileatt_name = $_FILES['fileatt']['name']; $headers = array ('From' => $from, 'To' => $to, 'Subject' => $subject); if (is_uploaded_file($fileatt)) { echo("<p>Inside 1</p>"); $file = fopen($fileatt,'rb'); $data = fread($file,filesize($fileatt)); fclose($file); // Generate a boundary string $semi_rand = md5(time()); $mime_boundary = "==Multipart_Boundary_x{$semi_rand}x"; array_push(&$headers, 'MIME-Version: 1.0'); array_push(&$headers, 'Content-Type: multipart/mixed;'); array_push(&$headers, " boundary=\"{$mime_boundary}\""); echo("<p>Inside 2</p>"); $body = "This is a multi-part message in MIME format.\n\n" . "--{$mime_boundary}\n" . "Content-Type: text/plain; charset=\"iso-8859-1\"\n" . "Content-Transfer-Encoding: 7bit\n\n" . $body . "\n\n"; echo("<p>Inside 3</p>"); $data = chunk_split(base64_encode($data)); echo("<p>Inside 4</p>"); $body .= "--{$mime_boundary}\n" . "Content-Type: {$fileatt_type};\n" . " name=\"{$fileatt_name}\"\n" . "Content-Transfer-Encoding: base64\n\n" . $data . "\n\n" . "--{$mime_boundary}--\n"; echo("<p>Inside 5</p>"); } $host = "[email protected]"; $username = "[email protected]"; $password = "user"; $smtp = Mail::factory('smtp', array ('host' => $host, 'auth' => true, 'username' => $username, 'password' => $password)); $mail = $smtp->send($to, $headers, $body); if (PEAR::isError($mail)) { echo("<p>" . $mail->getMessage() . "</p>"); } else { echo("<p>Message successfully sent!</p>"); } ?> Now this code works fine for me, and it's sending the mail to the target email address. But when I open this email in the inbox, it's showing me the following text in the mailbox: This is a multi-part message in MIME format. --==Multipart_Boundary_x368d72fe1ff44518e90537abdb4bf029x Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit test 1011 --==Multipart_Boundary_x368d72fe1ff44518e90537abdb4bf029x Content-Type: text/html; name="mailing.html" Content-Transfer-Encoding: base64 PCFET0NUWVBFIGh0bWwgUFVCTElDICItLy9XM0MvL0RURCBYSFRNTCAxLjAgVHJhbnNpdGlvbmFs Ly9FTiIgImh0dHA6Ly93d3cudzMub3JnL1RSL3hodG1sMS9EVEQveGh0bWwxLXRyYW5zaXRpb25h ................ So, it's clearly showing me the encoded data. So, what should modify to send the proper html page that should be visible in targeted email's inbox? Thanks in advance...

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• Hazelcast Distributed Executor Service KeyOwner

  - by János Veres

  I have problem understanding the concept of Hazelcast Distributed Execution. It is said to be able to perform the execution on the owner instance of a specific key. From Documentation: <T> Future<T> submitToKeyOwner(Callable<T> task, Object key) Submits task to owner of the specified key and returns a Future representing that task. Parameters: task - task key - key Returns: a Future representing pending completion of the task I believe that I'm not alone to have a cluster built with multiple maps which might actually use the same key for different purposes, holding different objects (e.g. something along the following setup): IMap<String, ObjectTypeA> firstMap = HazelcastInstance.getMap("firstMap"); IMap<String, ObjectTypeA_AppendixClass> secondMap = HazelcastInstance.getMap("secondMap"); To me it seems quite confusing what documentation says about the owner of a key. My real frustration is that I don't know WHICH - in which map - key does it refer to? The documentation also gives a "demo" of this approach: import com.hazelcast.core.Member; import com.hazelcast.core.Hazelcast; import com.hazelcast.core.IExecutorService; import java.util.concurrent.Callable; import java.util.concurrent.Future; import java.util.Set; import com.hazelcast.config.Config; public void echoOnTheMemberOwningTheKey(String input, Object key) throws Exception { Callable<String> task = new Echo(input); HazelcastInstance hz = Hazelcast.newHazelcastInstance(); IExecutorService executorService = hz.getExecutorService("default"); Future<String> future = executorService.submitToKeyOwner(task, key); String echoResult = future.get(); } Here's a link to the documentation site: Hazelcast MultiHTML Documentation 3.0 - Distributed Execution Did any of you guys figure out in the past what key does it want?

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• How to properly close a UDT server in Netty 4

  - by Steffen

  I'm trying to close my UDT server (Netty 4.0.5.Final) with shutDownGracefully() and reopen it on the same port. Unfortunately, I always get the socket exception below although it waits until the future has completed. I also added the socket option SO_REUSEADDR. What is the proper way to do this? Exception in thread "main" com.barchart.udt.ExceptionUDT: UDT Error : 5011 : another socket is already listening on the same UDP port : listen0:listen [id: 0x323d3939] at com.barchart.udt.SocketUDT.listen0(Native Method) at com.barchart.udt.SocketUDT.listen(SocketUDT.java:1136) at com.barchart.udt.net.NetServerSocketUDT.bind(NetServerSocketUDT.java:66) at io.netty.channel.udt.nio.NioUdtAcceptorChannel.doBind(NioUdtAcceptorChannel.java:71) at io.netty.channel.AbstractChannel$AbstractUnsafe.bind(AbstractChannel.java:471) at io.netty.channel.DefaultChannelPipeline$HeadHandler.bind(DefaultChannelPipeline.java:1006) at io.netty.channel.DefaultChannelHandlerContext.invokeBind(DefaultChannelHandlerContext.java:504) at io.netty.channel.DefaultChannelHandlerContext.bind(DefaultChannelHandlerContext.java:487) at io.netty.channel.ChannelDuplexHandler.bind(ChannelDuplexHandler.java:38) at io.netty.handler.logging.LoggingHandler.bind(LoggingHandler.java:254) at io.netty.channel.DefaultChannelHandlerContext.invokeBind(DefaultChannelHandlerContext.java:504) at io.netty.channel.DefaultChannelHandlerContext.bind(DefaultChannelHandlerContext.java:487) at io.netty.channel.DefaultChannelPipeline.bind(DefaultChannelPipeline.java:848) at io.netty.channel.AbstractChannel.bind(AbstractChannel.java:193) at io.netty.bootstrap.AbstractBootstrap$2.run(AbstractBootstrap.java:321) at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:354) at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:366) at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:101) at java.lang.Thread.run(Thread.java:724) A small test program demonstration the problem: public class MsgEchoServer { public static class MsgEchoServerHandler extends ChannelInboundHandlerAdapter { } public void run() throws Exception { final ThreadFactory acceptFactory = new UtilThreadFactory("accept"); final ThreadFactory connectFactory = new UtilThreadFactory("connect"); final NioEventLoopGroup acceptGroup = new NioEventLoopGroup(1, acceptFactory, NioUdtProvider.MESSAGE_PROVIDER); final NioEventLoopGroup connectGroup = new NioEventLoopGroup(1, connectFactory, NioUdtProvider.MESSAGE_PROVIDER); try { final ServerBootstrap boot = new ServerBootstrap(); boot.group(acceptGroup, connectGroup) .channelFactory(NioUdtProvider.MESSAGE_ACCEPTOR) .option(ChannelOption.SO_BACKLOG, 10) .option(ChannelOption.SO_REUSEADDR, true) .handler(new LoggingHandler(LogLevel.INFO)) .childHandler(new ChannelInitializer<UdtChannel>() { @Override public void initChannel(final UdtChannel ch) throws Exception { ch.pipeline().addLast(new MsgEchoServerHandler()); } }); final ChannelFuture future = boot.bind(1234).sync(); } finally { acceptGroup.shutdownGracefully().syncUninterruptibly(); connectGroup.shutdownGracefully().syncUninterruptibly(); } new MsgEchoServer().run(); } public static void main(final String[] args) throws Exception { new MsgEchoServer().run(); } }

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• Understanding Java Wait and Notify methods

  - by Maddy

  Hello all: I have a following program: import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class SimpleWaitNotify implements Runnable { final static Object obj = new Object(); static boolean value = true; public synchronized void flag() { System.out.println("Before Wait"); try { obj.wait(); } catch (InterruptedException e) { System.out.println("Thread interrupted"); } System.out.println("After Being Notified"); } public synchronized void unflag() { System.out.println("Before Notify All"); obj.notifyAll(); System.out.println("After Notify All Method Call"); } public void run() { if (value) { flag(); } else { unflag(); } } public static void main(String[] args) throws InterruptedException { ExecutorService pool = Executors.newFixedThreadPool(4); SimpleWaitNotify sWait = new SimpleWaitNotify(); pool.execute(sWait); SimpleWaitNotify.value = false; SimpleWaitNotify sNotify = new SimpleWaitNotify(); pool.execute(sNotify); pool.shutdown(); } } When I wait on obj, I get the following exception Exception in thread "pool-1-thread-1" java.lang.IllegalMonitorStateException: current thread not owner for each of the two threads. But if I use SimpleWaitNotify's monitor then the program execution is suspended. In other words, I think it suspends current execution thread and in turn the executor. Any help towards understanding what's going on would be duly appreciated. This is an area1 where the theory and javadoc seem straightforward, and since there aren't many examples, conceptually left a big gap in me.

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• Populating a GridView with ImageViews dynamically/programmatically using a ImageAdapter

  - by Julian Vogels

  Hi folks, this is my first question at stackoverflow, but it's a little tricky already... I try to develop an Android App which allows the user to fetch data from flickr and show it in a gridview (with some nice 3D-Animation). After some adventures i got it almost running, but now I'm stuck. Here's the problem: I got a UI Thread "LoadPhotosTask" which gets the pictures from flickr, just like the open source application photostream. In the method onProgressUpdate(LoadedPhoto... value) of that subclass I call addPhoto(). Until now everythings fine - I got some nice Bitmap and Flickr.photo data with all the information I need. @Override public void onProgressUpdate(LoadedPhoto... value) { addPhoto(value); } On the other hand I have got a GridView. Now I want to fill it with the Photos. It has got an adapter called ImageAdapter (which extends BaseAdapter, see this tutorial). If I use an array inside the ImageAdapter class I can populate the GridView with some sample images. But if I want to populate it at runtime, I don't know what to do. How do I have to set up the getView method in the ImageAdapter? I was trying to fill the array inside the ImageAdapter class with my values in addPhoto, but it doesn't display anything. So first of all I was setting up the array with the amount of Photos i wanted to display in the grid like that (code is inside the ImageAdapter class): // class variable private ImageView[] mThumbIds; [...] public void setupArray(int count) { this.mThumbIds = new ImageView[count]; } Then I call this method with the lenght of my photolist: final Flickr.PhotoList list = params[0]; final int count = list.getCount(); int helper = 0; imagead.setupArray(count); Afterwards I call the getView method manually inside the addPhoto method: private void addPhoto(LoadedPhoto... value) { ImageView image = (ImageView) mInflater.inflate( R.layout.grid_item_photo, null); image.setImageBitmap(value[0].mBitmap); image.setTag(value[0].mPhoto); imagead.setmThumbIds(image, value[0].mPosition); imagead.getView(value[0].mPosition, null, mpicturesGrid); } That is the getView method inside ImageAdapter: public View getView(int position, View convertView, ViewGroup parent) { if (convertView == null) { // if it's not recycled, initialize some // attributes imageView = new ImageView(mContext); imageView.setLayoutParams(new GridView.LayoutParams(EDGE_LENGTH, EDGE_LENGTH)); imageView.setScaleType(ImageView.ScaleType.CENTER_CROP); imageView.setPadding(0, 0, 0, 0); imageView.setVisibility(View.VISIBLE); } else { imageView = (ImageView) convertView; } imageView.setImageDrawable(mThumbIds[position].getDrawable()); imageView.setTag(mThumbIds[position].getTag()); return imageView; } Ok, finally I apologize for my poor english and I hope you can give me some help with the information I provided. Greetings, Julian

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• how to restart a Thread?

  - by wizztjh

  It is a RMI Server object , so many sethumanActivity() might be run , how do i make sure the previous changeToFalse thread will be stop or halt before the new changeToFalse run? t. interrupt ? Basically when sethumanActivity() is invoke , the humanActivity will be set to true , but a thread will be run to set it back to false. But I am thinking for how to disable or kill the thread when another sethumanActivity() invoked? public class VitaminDEngine implements VitaminD { public boolean humanActivity = false; changeToFalse cf = new changeToFalse(); Thread t = new Thread(cf); private class changeToFalse implements Runnable{ @Override public void run() { try { Thread.sleep(4000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } humanActivity = false; } } @Override public void sethumanActivity() throws RemoteException { // TODO Auto-generated method stub humanActivity = true; t.start(); } public boolean gethumanActivity() throws RemoteException { // TODO Auto-generated method stub return humanActivity; } } Edited after the help of SOer package smartOfficeJava; import java.rmi.RemoteException; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class VitaminDEngine implements VitaminD { public volatile boolean humanActivity = false; changeToFalse cf = new changeToFalse(); ExecutorService service = Executors.newSingleThreadExecutor(); private class changeToFalse implements Runnable{ @Override public void run() { try { Thread.sleep(4000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } humanActivity = false; } } @Override public synchronized void sethumanActivity() throws RemoteException { humanActivity = true; service.submit(cf); } public synchronized boolean gethumanActivity() throws RemoteException { return humanActivity; } }

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• volatile keyword seems to be useless?

  - by Finbarr

  import java.util.concurrent.CountDownLatch; import java.util.concurrent.atomic.AtomicInteger; public class Main implements Runnable { private final CountDownLatch cdl1 = new CountDownLatch(NUM_THREADS); private volatile int bar = 0; private AtomicInteger count = new AtomicInteger(0); private static final int NUM_THREADS = 25; public static void main(String[] args) { Main main = new Main(); for(int i = 0; i < NUM_THREADS; i++) new Thread(main).start(); } public void run() { int i = count.incrementAndGet(); cdl1.countDown(); try { cdl1.await(); } catch (InterruptedException e1) { e1.printStackTrace(); } bar = i; if(bar != i) System.out.println("Bar not equal to i"); else System.out.println("Bar equal to i"); } } Each Thread enters the run method and acquires a unique, thread confined, int variable i by getting a value from the AtomicInteger called count. Each Thread then awaits the CountDownLatch called cdl1 (when the last Thread reaches the latch, all Threads are released). When the latch is released each thread attempts to assign their confined i value to the shared, volatile, int called bar. I would expect every Thread except one to print out "Bar not equal to i", but every Thread prints "Bar equal to i". Eh, wtf does volatile actually do if not this?

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• Create new or update existing entity at one go with JPA

  - by Alex R

  A have a JPA entity that has timestamp field and is distinguished by a complex identifier field. What I need is to update timestamp in an entity that has already been stored, otherwise create and store new entity with the current timestamp. As it turns out the task is not as simple as it seems from the first sight. The problem is that in concurrent environment I get nasty "Unique index or primary key violation" exception. Here's my code: // Load existing entity, if any. Entity e = entityManager.find(Entity.class, id); if (e == null) { // Could not find entity with the specified id in the database, so create new one. e = entityManager.merge(new Entity(id)); } // Set current time... e.setTimestamp(new Date()); // ...and finally save entity. entityManager.flush(); Please note that in this example entity identifier is not generated on insert, it is known in advance. When two or more of threads run this block of code in parallel, they may simultaneously get null from entityManager.find(Entity.class, id) method call, so they will attempt to save two or more entities at the same time, with the same identifier resulting in error. I think that there are few solutions to the problem. Sure I could synchronize this code block with a global lock to prevent concurrent access to the database, but would it be the most efficient way? Some databases support very handy MERGE statement that updates existing or creates new row if none exists. But I doubt that OpenJPA (JPA implementation of my choice) supports it. Event if JPA does not support SQL MERGE, I can always fall back to plain old JDBC and do whatever I want with the database. But I don't want to leave comfortable API and mess with hairy JDBC+SQL combination. There is a magic trick to fix it using standard JPA API only, but I don't know it yet. Please help.

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