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• Is Akka a good solution for a concurrent pipeline/workflow problem?

  - by herpylderp

  Disclaimer: I am brand new to Akka and the concept of Actors/Event-Driven Architectures in general. I have to implement a fairly complex problem where users can configure a "concurrent pipeline": Pipeline: consists of 1+ Stages; all Stages execute sequentially Stage: consists of 1+ Tasks; all Tasks execute in parallel Task: essentially a Java Runnable As you can see above, a Task is a Runnable that does some unit of work. Tasks are organized into Stages, which execute their Tasks in parallel. Stages are organized into the Pipeline, which executes its Stages sequentially. Hence if a user specifies the following Pipeline: CrossTheRoadSafelyPipeline Stage 1: Look Left Task 1: Turn your head to the left and look for cars Task 2: Listen for cars Stage 2: Look right Task 1: Turn your head to the right and look for cars Task 2: Listen for cars Then, Stage 1 will execute, and then Stage 2 will execute. However, while each Stage is executing, it's individual Tasks are executing in parallel/at the same time. In reality Pipelines will become very complicated, and with hundreds of Stages, dozens of Tasks per Stage (again, executing at the same time). To implement this Pipeline I can only think of several solutions: ESB/Apache Camel Guava Event Bus Java 5 Concurrency Actors/Akka Camel doesn't seem right because its core competency is integration not synchrony and orchestration across worker threads. Guava is great, but this doesn't really feel like a subscriber/publisher-type of problem. And Java 5 Concurrency (ExecutorService, etc.) just feels too low-level and painful. So I ask: is Akka a strong candidate for this type of problem? If so, how? If not, then why, and what is a good candidate?

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• ActiveMQ - "Cannot send, channel has already failed" every 2 seconds?

  - by quanta

  ActiveMQ 5.7.0 In the activemq.log, I'm seeing this exception every 2 seconds: 2013-11-05 13:00:52,374 | DEBUG | Transport Connection to: tcp://127.0.0.1:37501 failed: org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://127.0.0.1:37501 | org.apache.activemq.broker.TransportConnection.Transport | Async Exception Handler org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://127.0.0.1:37501 at org.apache.activemq.transport.AbstractInactivityMonitor.doOnewaySend(AbstractInactivityMonitor.java:282) at org.apache.activemq.transport.AbstractInactivityMonitor.oneway(AbstractInactivityMonitor.java:271) at org.apache.activemq.transport.TransportFilter.oneway(TransportFilter.java:85) at org.apache.activemq.transport.WireFormatNegotiator.oneway(WireFormatNegotiator.java:104) at org.apache.activemq.transport.MutexTransport.oneway(MutexTransport.java:68) at org.apache.activemq.broker.TransportConnection.dispatch(TransportConnection.java:1312) at org.apache.activemq.broker.TransportConnection.processDispatch(TransportConnection.java:838) at org.apache.activemq.broker.TransportConnection.iterate(TransportConnection.java:873) at org.apache.activemq.thread.PooledTaskRunner.runTask(PooledTaskRunner.java:129) at org.apache.activemq.thread.PooledTaskRunner$1.run(PooledTaskRunner.java:47) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:662) Due to this keyword InactivityIOException, the first thing comes to my mind is InactivityMonitor, but the strange thing is MaxInactivityDuration=30000: 2013-11-05 13:11:02,672 | DEBUG | Sending: WireFormatInfo { version=9, properties={MaxFrameSize=9223372036854775807, CacheSize=1024, CacheEnabled=true, SizePrefixDisabled=false, MaxInactivityDurationInitalDelay=10000, TcpNoDelayEnabled=true, MaxInactivityDuration=30000, TightEncodingEnabled=true, StackTraceEnabled=true}, magic=[A,c,t,i,v,e,M,Q]} | org.apache.activemq.transport.WireFormatNegotiator | ActiveMQ BrokerService[localhost] Task-2 Moreover, I also didn't see something like this: No message received since last read check for ... or: Channel was inactive for too (30000) long Do a netstat, I see these connections in TIME_WAIT state: tcp 0 0 127.0.0.1:38545 127.0.0.1:61616 TIME_WAIT - tcp 0 0 127.0.0.1:38544 127.0.0.1:61616 TIME_WAIT - tcp 0 0 127.0.0.1:38522 127.0.0.1:61616 TIME_WAIT - Here're the output when running tcpdump: Internet Protocol Version 4, Src: 127.0.0.1 (127.0.0.1), Dst: 127.0.0.1 (127.0.0.1) Version: 4 Header length: 20 bytes Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00: Not-ECT (Not ECN-Capable Transport)) 0000 00.. = Differentiated Services Codepoint: Default (0x00) .... ..00 = Explicit Congestion Notification: Not-ECT (Not ECN-Capable Transport) (0x00) Total Length: 296 Identification: 0x7b6a (31594) Flags: 0x02 (Don't Fragment) 0... .... = Reserved bit: Not set .1.. .... = Don't fragment: Set ..0. .... = More fragments: Not set Fragment offset: 0 Time to live: 64 Protocol: TCP (6) Header checksum: 0xc063 [correct] [Good: True] [Bad: False] Source: 127.0.0.1 (127.0.0.1) Destination: 127.0.0.1 (127.0.0.1) Transmission Control Protocol, Src Port: 61616 (61616), Dst Port: 54669 (54669), Seq: 1, Ack: 2, Len: 244 Source port: 61616 (61616) Destination port: 54669 (54669) [Stream index: 11] Sequence number: 1 (relative sequence number) [Next sequence number: 245 (relative sequence number)] Acknowledgement number: 2 (relative ack number) Header length: 32 bytes Flags: 0x018 (PSH, ACK) 000. .... .... = Reserved: Not set ...0 .... .... = Nonce: Not set .... 0... .... = Congestion Window Reduced (CWR): Not set .... .0.. .... = ECN-Echo: Not set .... ..0. .... = Urgent: Not set .... ...1 .... = Acknowledgement: Set .... .... 1... = Push: Set .... .... .0.. = Reset: Not set .... .... ..0. = Syn: Not set .... .... ...0 = Fin: Not set Window size value: 256 [Calculated window size: 32768] [Window size scaling factor: 128] Checksum: 0xff1c [validation disabled] [Good Checksum: False] [Bad Checksum: False] Options: (12 bytes) No-Operation (NOP) No-Operation (NOP) Timestamps: TSval 2304161892, TSecr 2304161891 Kind: Timestamp (8) Length: 10 Timestamp value: 2304161892 Timestamp echo reply: 2304161891 [SEQ/ACK analysis] [Bytes in flight: 244] Constrained Application Protocol, TID: 240, Length: 244 00.. .... = Version: 0 ..00 .... = Type: Confirmable (0) .... 0000 = Option Count: 0 Code: Unknown (0) Transaction ID: 240 Payload Content-Type: text/plain (default), Length: 240, offset: 4 Line-based text data: text/plain [truncated] \001ActiveMQ\000\000\000\t\001\000\000\000<DE>\000\000\000\t\000\fMaxFrameSize\006\177<FF><FF><FF><FF> <FF><FF><FF>\000\tCacheSize\005\000\000\004\000\000\fCacheEnabled\001\001\000\022SizePrefixDisabled\001\000\000 MaxInactivityDurationInitalDelay\006\ It is very likely a tcp port check. This is what I see when trying telnet from another host: 2013-11-05 16:12:41,071 | DEBUG | Transport Connection to: tcp://10.8.20.9:46775 failed: java.io.EOFException | org.apache.activemq.broker.TransportConnection.Transport | ActiveMQ Transport: tcp:///10.8.20.9:46775@61616 java.io.EOFException at java.io.DataInputStream.readInt(DataInputStream.java:375) at org.apache.activemq.openwire.OpenWireFormat.unmarshal(OpenWireFormat.java:275) at org.apache.activemq.transport.tcp.TcpTransport.readCommand(TcpTransport.java:229) at org.apache.activemq.transport.tcp.TcpTransport.doRun(TcpTransport.java:221) at org.apache.activemq.transport.tcp.TcpTransport.run(TcpTransport.java:204) at java.lang.Thread.run(Thread.java:662) 2013-11-05 16:12:41,071 | DEBUG | Transport Connection to: tcp://10.8.20.9:46775 failed: org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection.Transport | Async Exception Handler org.apache.activemq.transport.InactivityIOException: Cannot send, channel has already failed: tcp://10.8.20.9:46775 at org.apache.activemq.transport.AbstractInactivityMonitor.doOnewaySend(AbstractInactivityMonitor.java:282) at org.apache.activemq.transport.AbstractInactivityMonitor.oneway(AbstractInactivityMonitor.java:271) at org.apache.activemq.transport.TransportFilter.oneway(TransportFilter.java:85) at org.apache.activemq.transport.WireFormatNegotiator.oneway(WireFormatNegotiator.java:104) at org.apache.activemq.transport.MutexTransport.oneway(MutexTransport.java:68) at org.apache.activemq.broker.TransportConnection.dispatch(TransportConnection.java:1312) at org.apache.activemq.broker.TransportConnection.processDispatch(TransportConnection.java:838) at org.apache.activemq.broker.TransportConnection.iterate(TransportConnection.java:873) at org.apache.activemq.thread.PooledTaskRunner.runTask(PooledTaskRunner.java:129) at org.apache.activemq.thread.PooledTaskRunner$1.run(PooledTaskRunner.java:47) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:662) 2013-11-05 16:12:41,071 | DEBUG | Unregistering MBean org.apache.activemq:BrokerName=localhost,Type=Connection,ConnectorName=ope nwire,ViewType=address,Name=tcp_//10.8.20.9_46775 | org.apache.activemq.broker.jmx.ManagementContext | ActiveMQ Transport: tcp:/ //10.8.20.9:46775@61616 2013-11-05 16:12:41,073 | DEBUG | Stopping connection: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,073 | DEBUG | Stopping transport tcp:///10.8.20.9:46775@61616 | org.apache.activemq.transport.tcp.TcpTranspo rt | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,073 | DEBUG | Initialized TaskRunnerFactory[ActiveMQ Task] using ExecutorService: java.util.concurrent.Threa dPoolExecutor@23cc2a28 | org.apache.activemq.thread.TaskRunnerFactory | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,074 | DEBUG | Closed socket Socket[addr=/10.8.20.9,port=46775,localport=61616] | org.apache.activemq.transpo rt.tcp.TcpTransport | ActiveMQ Task-1 2013-11-05 16:12:41,074 | DEBUG | Forcing shutdown of ExecutorService: java.util.concurrent.ThreadPoolExecutor@23cc2a28 | org.apache.activemq.util.ThreadPoolUtils | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,074 | DEBUG | Stopped transport: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,074 | DEBUG | Connection Stopped: tcp://10.8.20.9:46775 | org.apache.activemq.broker.TransportConnection | ActiveMQ BrokerService[localhost] Task-5 2013-11-05 16:12:41,902 | DEBUG | Sending: WireFormatInfo { version=9, properties={MaxFrameSize=9223372036854775807, CacheSize=1024, CacheEnabled=true, SizePrefixDisabled=false, MaxInactivityDurationInitalDelay=10000, TcpNoDelayEnabled=true, MaxInactivityDuration=30000, TightEncodingEnabled=true, StackTraceEnabled=true}, magic=[A,c,t,i,v,e,M,Q]} | org.apache.activemq.transport.WireFormatNegotiator | ActiveMQ BrokerService[localhost] Task-5 So the question is: how can I find out the process that is trying to connect to my ActiveMQ (from localhost) every 2 seconds?

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• Java - Difference between SwingWorker and SwingUtilities.invokeLater()

  - by Yatendra Goel

  SwingWorker is used for the following purposes: For running long-running tasks in a different thread so as to prevent the GUI from being unresponsive For updating GUI with the results produced by the long-running task at the end of the task through done() method. For updating GUI from time to time with the intermediate results produced and published by the task with the help of publish() and process() methods. SwingUtilities.invokeLater() can perform the above tasks as follows: Instead of executing SwingWorker.execute() method from the EDT, we can execute ExecutorService.submit(new MyRunnable()) as it will also create another thread which can execute long-running task. For updating GUI at the end of the task, we can put code (written in done() method of case1) SwingUtilites.invokeLater(new RunnableToExecuteDoneMethodCode()) at the end of the task. For updating GUI in the middle of the task, we can put code (written in process() method of case1) SwingUtilites.invokeLater(new RunnableToExecuteProcessMethodCode()) at the place where we called publish() method in case1. I am asking this question because the problem specified in question http://stackoverflow.com/questions/2797483/java-swingworker-can-we-call-one-swingworker-from-other-swingworker-instead-o/2824306#2824306 can be solved by SwingUtilities.invokeLater() but can't be solved with SwingWorker

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• Java Future and infinite computation

  - by Chris

  I'm trying to optimize an (infinite) computation algorithm. I have an infinte Sum to calculate ( Summ_{n- infinity} (....) ) My idea was to create several threads using the Future < construct, then combine the intermediate results together. My problem hoewer is that I need a certain precision. So I need to constantly calculate the current result while other threads keep calculating. My question is: Is there some sort of result queue where each finished thread can put its results in, while a main thread can receive those results and then either lets the computation continues or terminate the whole ExecutorService? Any Help would really be appreciated! Thanks!

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• JAVA: 500 Worker Threads, what kind of thread pool?

  - by Submerged

  I am wondering if this is the best way to do this. I have about 500 threads that run indefinitely, but Thread.sleep for a minute when done one cycle of processing. ExecutorService es = Executors.newFixedThreadPool(list.size()+1); for (int i = 0; i < list.size(); i++) { es.execute(coreAppVector.elementAt(i)); //coreAppVector is a vector of extends thread objects } I do need a separate threads for each running task, so changing the architecture isn't an option. I tried making my threadPool size equal to Runtime.getRuntime().availableProcessors() which attempted to run all 500 threads, but only let 8 (4xhyperthreading) of them execute. The other threads wouldn't surrender and let other threads have their turn. I tried putting in a wait() and notify(), but still no luck. If anyone has a simple example or some tips, I would be grateful!

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• Java: serial thread confinement question

  - by denis

  Assume you have a Collection(ConcurrentLinkedQueue) of Runnables with mutable state. Thread A iterates over the Collection and hands the Runnables to an ExecutorService. The run() method changes the Runnables state. The Runnable has no internal synchronization. The above is a repetitive action and the worker threads need to see the changes made by previous iterations. So a Runnable gets processed by one worker thread after another, but is never accessed by more than one thread at a time - a case of serial thread confinement(i hope ;)). The question: Will it work just with the internal synchronization of the ConcurrentLinkedQueue/ExecutorSerivce? To be more precise: If Thread A hands Runnable R to worker thread B and B changes the state of R, and then A hands R to worker thread C..does C see the modifications done by B?

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• controlling the order of submitted futures

  - by mac

  In this example, i am submitting a few files to my comparator object. It all works fine, except that i noticed that order in which files are submitted is not always teh same order in which they are returned. Any suggestions on how i can better control this? ExecutorService pool = Executors.newFixedThreadPool(5); CompletionService<Properties> completion = new ExecutorCompletionService<Properties>(pool); for (String target : p.getTargetFiles()) { completion.submit(new PropertiesLoader(target, p)); } for (@SuppressWarnings("unused") String target : p.getTargetFiles()) { Properties r = null; try { r = completion.take().get(); } catch (InterruptedException e) { e.printStackTrace(); } catch (ExecutionException e) { e.printStackTrace(); } p.addTargetFilesProperties(r); } pool.shutdown();

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• Java: Allowing the child thread to kill itself on InterruptedException?

  - by Zombies

  I am using a ThreadPool via ExecutorService. By calling shutDownNow() it interrupts all running threads in the pool. When this happens I want these threads to give up their resources (socket and db connections) and simply die, but without continuing to run anymore logic, eg: inserting anything into the DB. What is the simplest way to achieve this? Bellow is some sample code: public void threadTest() { Thread t = new Thread(new Runnable() { public void run() { try { Thread.sleep(999999); } catch (InterruptedException e) { //invoke thread suicide logic here } } }); t.start(); t.interrupt(); try { Thread.sleep(4000); } catch (InterruptedException e) { } }

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• java.lang.OutOfMemoryError: unable to create new native thread for multiple threads

  - by Kaustubh Ranjan Singh

  static class solver implements Runnable { static calculator(problem){ //Some code if(condition) {solver s = new solver(newproblem); new Thread(s).start();} } Public solver(int newproblem) { this.problem = newproblem ; } public void run() { // TODO Auto-generated method stub calculator(promblem); } } i am having a big array maze of 100x100 and i am trying to solve it and i am getting an error java.lang.OutOfMemoryError: unable to create new native thread(after running a code for some times). How can solve this , How can i use ExecutorService i think that will solve the problem or i want something like thisIf Number of generated threads4K then stop the first 100 threads

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• How to tell if there is an available thread in a thread pool in java

  - by Gormcito

  I am trying to proccess a queue of tasks from a database table as fast as possible while also limiting the number of threads to process the tasks. I am using a fixed sized thread pool with Executors.newFixedThreadPool(N); I want to know if there is a way of knowing if the thread pool is full, by that I mean are there currently 50 threads running, if so then I'll wait for a thread to be available before starting a new one instead of sleeping the main thread. Code of what I would like to do: ExecutorService executor = Executors.newFixedThreadPool(N); ResultSet results; while( true ) { results = getWaitingTasksStmt.executeQuery(); while( results.next() && executor.notFull() ) { executor.submit( new thread( new runnableInheritedClass(results) ) ); } }

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• Spring, JPA, Hibernate, Jetty 7 Integration

  - by Jewel

  Have anyone successfully run any spring and JPA application in jetty 7? I am getting following exception. This application throws no error in jetty 6. INFO [main] org.eclipse.jetty.util.log - Logging to org.slf4j.impl.Log4jLoggerAdapter(org.eclipse.jetty.util.log) via org.eclipse.jetty.util.log.Slf4jLog INFO [main] org.eclipse.jetty.util.log - jetty-7.1.2.v20100523 INFO [main] org.eclipse.jetty.util.log - Deployment monitor G:\_Java\_Jetty\jetty-distribution-7.1.2.v20100523\contexts at interval 5 INFO [main] org.eclipse.jetty.util.log - Deployment monitor G:\_Java\_Jetty\jetty-distribution-7.1.2.v20100523\webapps at interval 5 INFO [main] org.eclipse.jetty.util.log - Deployable added: G:\_Java\_Jetty\jetty-distribution-7.1.2.v20100523\webapps\gwtrpc-spring.war INFO [main] org.eclipse.jetty.util.log - Copying WEB-INF/lib jar:file:/G:/_Java/_Jetty/jetty-distribution-7.1.2.v20100523/webapps/gwtrpc-spring.war!/WEB-INF/lib/ to C:\Documents and Settings\Jewel2\Local Settings\Temp\Jetty_0_0_0_0_8080_gwtrpc.spring.war__gwtrpc.spring__az1wdj\webinf\WEB-INF\lib INFO [main] org.eclipse.jetty.util.log - Copying WEB-INF/classes from jar:file:/G:/_Java/_Jetty/jetty-distribution-7.1.2.v20100523/webapps/gwtrpc-spring.war!/WEB-INF/classes/ to C:\Documents and Settings\Jewel2\Local Settings\Temp\Jetty_0_0_0_0_8080_gwtrpc.spring.war__gwtrpc.spring__az1wdj\webinf\WEB-INF\classes INFO [main] /gwtrpc-spring - Initializing Spring root WebApplicationContext INFO [main] org.springframework.web.context.ContextLoader - Root WebApplicationContext: initialization started INFO [main] org.springframework.web.context.support.XmlWebApplicationContext - Refreshing Root WebApplicationContext: startup date [Thu Jun 10 00:13:32 GMT+06:00 2010]; root of context hierarchy INFO [main] org.springframework.beans.factory.xml.XmlBeanDefinitionReader - Loading XML bean definitions from ServletContext resource [/WEB-INF/applicationContext.xml] INFO [main] org.springframework.beans.factory.support.DefaultListableBeanFactory - Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@467991: defining beans [org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.context.annotation.internalPersistenceAnnotationProcessor,greetingServiceImpl,testService,testService2,taskExecutor,dataSource,entityManagerFactory,org.springframework.aop.config.internalAutoProxyCreator,org.springframework.transaction.annotation.AnnotationTransactionAttributeSource#0,org.springframework.transaction.interceptor.TransactionInterceptor#0,org.springframework.transaction.config.internalTransactionAdvisor,transactionManager,org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor#0]; root of factory hierarchy INFO [main] org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor - Initializing ExecutorService 'taskExecutor' INFO [main] org.springframework.jdbc.datasource.DriverManagerDataSource - Loaded JDBC driver: com.mysql.jdbc.Driver INFO [main] org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean - Building JPA container EntityManagerFactory for persistence unit 'gwtrpc-spring-data-source' INFO [main] org.hibernate.cfg.annotations.Version - Hibernate Annotations 3.4.0.GA INFO [main] org.hibernate.cfg.Environment - Hibernate 3.3.1.GA INFO [main] org.hibernate.cfg.Environment - hibernate.properties not found INFO [main] org.hibernate.cfg.Environment - Bytecode provider name : javassist INFO [main] org.hibernate.cfg.Environment - using JDK 1.4 java.sql.Timestamp handling INFO [main] org.hibernate.annotations.common.Version - Hibernate Commons Annotations 3.1.0.GA INFO [main] org.hibernate.ejb.Version - Hibernate EntityManager 3.4.0.GA INFO [main] org.hibernate.ejb.Ejb3Configuration - Processing PersistenceUnitInfo [ name: gwtrpc-spring-data-source ...] INFO [main] org.springframework.beans.factory.support.DefaultListableBeanFactory - Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@467991: defining beans [org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.context.annotation.internalPersistenceAnnotationProcessor,greetingServiceImpl,testService,testService2,taskExecutor,dataSource,entityManagerFactory,org.springframework.aop.config.internalAutoProxyCreator,org.springframework.transaction.annotation.AnnotationTransactionAttributeSource#0,org.springframework.transaction.interceptor.TransactionInterceptor#0,org.springframework.transaction.config.internalTransactionAdvisor,transactionManager,org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor#0]; root of factory hierarchy INFO [main] org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor - Shutting down ExecutorService 'taskExecutor' ERROR [main] org.springframework.web.context.ContextLoader - Context initialization failed org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in ServletContext resource [/WEB-INF/applicationContext.xml]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: gwtrpc-spring-data-source] class or package not found at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1403) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:450) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:290) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:287) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:189) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:545) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:871) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:423) at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:272) at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:196) at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:47) at org.eclipse.jetty.server.handler.ContextHandler.startContext(ContextHandler.java:636) at org.eclipse.jetty.servlet.ServletContextHandler.startContext(ServletContextHandler.java:188) at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:995) at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:579) at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:381) at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:55) at org.eclipse.jetty.deploy.bindings.StandardStarter.processBinding(StandardStarter.java:36) at org.eclipse.jetty.deploy.AppLifeCycle.runBindings(AppLifeCycle.java:182) at org.eclipse.jetty.deploy.DeploymentManager.requestAppGoal(DeploymentManager.java:497) at org.eclipse.jetty.deploy.DeploymentManager.addApp(DeploymentManager.java:135) at org.eclipse.jetty.deploy.providers.ScanningAppProvider$1.fileAdded(ScanningAppProvider.java:61) at org.eclipse.jetty.util.Scanner.reportAddition(Scanner.java:436) at org.eclipse.jetty.util.Scanner.reportDifferences(Scanner.java:349) at org.eclipse.jetty.util.Scanner.scan(Scanner.java:306) at org.eclipse.jetty.util.Scanner.start(Scanner.java:242) at org.eclipse.jetty.deploy.providers.ScanningAppProvider.doStart(ScanningAppProvider.java:136) at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:55) at org.eclipse.jetty.deploy.DeploymentManager.startAppProvider(DeploymentManager.java:562) at org.eclipse.jetty.deploy.DeploymentManager.doStart(DeploymentManager.java:212) at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:55) at org.eclipse.jetty.server.Server.doStart(Server.java:209) at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:55) at org.eclipse.jetty.xml.XmlConfiguration$1.run(XmlConfiguration.java:1018) at java.security.AccessController.doPrivileged(Native Method) at org.eclipse.jetty.xml.XmlConfiguration.main(XmlConfiguration.java:983) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.eclipse.jetty.start.Main.invokeMain(Main.java:447) at org.eclipse.jetty.start.Main.start(Main.java:605) at org.eclipse.jetty.start.Main.parseCommandLine(Main.java:238) at org.eclipse.jetty.start.Main.main(Main.java:77) Caused by: javax.persistence.PersistenceException: [PersistenceUnit: gwtrpc-spring-data-source] class or package not found at org.hibernate.ejb.Ejb3Configuration.addNamedAnnotatedClasses(Ejb3Configuration.java:1093) at org.hibernate.ejb.Ejb3Configuration.addClassesToSessionFactory(Ejb3Configuration.java:871) at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:758) at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:425) at org.hibernate.ejb.HibernatePersistence.createContainerEntityManagerFactory(HibernatePersistence.java:131) at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:225) at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:308) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1460) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1400) ... 45 more Caused by: java.lang.ClassNotFoundException: WEB-INF.classes.org.gwtrpcspring.example.server.Person at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClassInternal(Unknown Source) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Unknown Source) at org.hibernate.util.ReflectHelper.classForName(ReflectHelper.java:135) at org.hibernate.ejb.Ejb3Configuration.classForName(Ejb3Configuration.java:1009) at org.hibernate.ejb.Ejb3Configuration.addNamedAnnotatedClasses(Ejb3Configuration.java:1081) ... 53 more WARN [main] org.eclipse.jetty.util.log - Failed startup of context WebAppContext@149f041@149f041/gwtrpc-spring,file:/C:/Documents and Settings/Jewel2/Local Settings/Temp/Jetty_0_0_0_0_8080_gwtrpc.spring.war__gwtrpc.spring__az1wdj/webinf/;jar:file:/G:/_Java/_Jetty/jetty-distribution-7.1.2.v20100523/webapps/gwtrpc-spring.war!/;,G:\_Java\_Jetty\jetty-distribution-7.1.2.v20100523\webapps\gwtrpc-spring.war org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in ServletContext resource [/WEB-INF/applicationContext.xml]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: gwtrpc-spring-data-source] class or package not found at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1403) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:450) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:290) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:287) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:189) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:545) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:871) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:423) at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:272) at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:196) at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:47) at org.eclipse.jetty.server.handler.ContextHandler.startContext(ContextHandler.java:636) at org.eclipse.jetty.servlet.ServletContextHandler.startContext(ServletContextHandler.java:188) at org.eclipse.jetty.webapp.WebAppContext.startContext(WebAppContext.java:995) at org.eclipse.jetty.server.handler.ContextHandler.doStart(ContextHandler.java:579) at org.eclipse.jetty.webapp.WebAppContext.doStart(WebAppContext.java:381) at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:55) at org.eclipse.jetty.deploy.bindings.StandardStarter.processBinding(StandardStarter.java:36) at org.eclipse.jetty.deploy.AppLifeCycle.runBindings(AppLifeCycle.java:182) at org.eclipse.jetty.deploy.DeploymentManager.requestAppGoal(DeploymentManager.java:497) at org.eclipse.jetty.deploy.DeploymentManager.addApp(DeploymentManager.java:135) at org.eclipse.jetty.deploy.providers.ScanningAppProvider$1.fileAdded(ScanningAppProvider.java:61) at org.eclipse.jetty.util.Scanner.reportAddition(Scanner.java:436) at org.eclipse.jetty.util.Scanner.reportDifferences(Scanner.java:349) at org.eclipse.jetty.util.Scanner.scan(Scanner.java:306) at org.eclipse.jetty.util.Scanner.start(Scanner.java:242) at org.eclipse.jetty.deploy.providers.ScanningAppProvider.doStart(ScanningAppProvider.java:136) at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:55) at org.eclipse.jetty.deploy.DeploymentManager.startAppProvider(DeploymentManager.java:562) at org.eclipse.jetty.deploy.DeploymentManager.doStart(DeploymentManager.java:212) at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:55) at org.eclipse.jetty.server.Server.doStart(Server.java:209) at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:55) at org.eclipse.jetty.xml.XmlConfiguration$1.run(XmlConfiguration.java:1018) at java.security.AccessController.doPrivileged(Native Method) at org.eclipse.jetty.xml.XmlConfiguration.main(XmlConfiguration.java:983) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.eclipse.jetty.start.Main.invokeMain(Main.java:447) at org.eclipse.jetty.start.Main.start(Main.java:605) at org.eclipse.jetty.start.Main.parseCommandLine(Main.java:238) at org.eclipse.jetty.start.Main.main(Main.java:77) Caused by: javax.persistence.PersistenceException: [PersistenceUnit: gwtrpc-spring-data-source] class or package not found at org.hibernate.ejb.Ejb3Configuration.addNamedAnnotatedClasses(Ejb3Configuration.java:1093) at org.hibernate.ejb.Ejb3Configuration.addClassesToSessionFactory(Ejb3Configuration.java:871) at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:758) at org.hibernate.ejb.Ejb3Configuration.configure(Ejb3Configuration.java:425) at org.hibernate.ejb.HibernatePersistence.createContainerEntityManagerFactory(HibernatePersistence.java:131) at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:225) at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:308) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1460) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1400) ... 45 more Caused by: java.lang.ClassNotFoundException: WEB-INF.classes.org.gwtrpcspring.example.server.Person at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClassInternal(Unknown Source) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Unknown Source) at org.hibernate.util.ReflectHelper.classForName(ReflectHelper.java:135) at org.hibernate.ejb.Ejb3Configuration.classForName(Ejb3Configuration.java:1009) at org.hibernate.ejb.Ejb3Configuration.addNamedAnnotatedClasses(Ejb3Configuration.java:1081) ... 53 more INFO [main] org.eclipse.jetty.util.log - Started [email protected]:8080 And this is my applicationContext.xml file <?xml version="1.0" encoding="UTF-8"?> <beans> <context:annotation-config /> <context:component-scan base-package="org.gwtrpcspring.example.server" /> <bean id="taskExecutor" class="org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor"> <property name="corePoolSize" value="5" /> <property name="maxPoolSize" value="10" /> <property name="queueCapacity" value="25" /> </bean> <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="driverClassName" value="com.mysql.jdbc.Driver" /> <property name="url" value="jdbc:mysql://localhost:3306/test" /> <property name="username" value="jewel" /> <property name="password" value="jewel" /> </bean> <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="dataSource" ref="dataSource" /> <property name="jpaVendorAdapter"> <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"> <property name="databasePlatform" value="org.hibernate.dialect.MySQLDialect" /> <!-- <property name="databasePlatform" value="org.hibernate.dialect.HSQLDialect" /> --> <property name="showSql" value="false" /> <property name="generateDdl" value="true" /> </bean> </property> </bean> <tx:annotation-driven /> <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"> <property name="entityManagerFactory" ref="entityManagerFactory" /> </bean> <bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" /> </beans>

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• Can't get SWT Display on Mac OS X.

  - by Mattias Holmqvist

  I'm running Mac OS X Snow Leopard and wan't to access the Display from the activator in an OSGi bundle. Below is the start method for my activator: @Override public void start(BundleContext context) throws Exception { ExecutorService service = Executors.newSingleThreadExecutor(); service.execute(new Runnable() { @Override public void run() { Display display = Display.getDefault(); Shell shell = new Shell(display); Text helloText = new Text(shell, SWT.CENTER); helloText.setText("Hello SWT!"); helloText.pack(); shell.pack(); shell.open(); while (!shell.isDisposed()) { if (!display.readAndDispatch()) display.sleep(); } display.dispose(); } }); } Calling this code in a Windows environment works fine, but deploying on Mac OS X I get the following output: 2009-10-14 17:17:54.050 java[2010:10003] *** __NSAutoreleaseNoPool(): Object 0x101620d20 of class NSCFString autoreleased with no pool in place - just leaking 2009-10-14 17:17:54.081 java[2010:10003] *** __NSAutoreleaseNoPool(): Object 0x100119240 of class NSCFNumber autoreleased with no pool in place - just leaking 2009-10-14 17:17:54.084 java[2010:10003] *** __NSAutoreleaseNoPool(): Object 0x1001024b0 of class NSCFString autoreleased with no pool in place - just leaking 2009-10-14 17:17:54.086 java[2010:10003] *** __NSAutoreleaseNoPool(): Object 0x7fff701d7f70 of class NSCFString autoreleased with no pool in place - just leaking 2009-10-14 17:17:54.087 java[2010:10003] *** __NSAutoreleaseNoPool(): Object 0x100113330 of class NSCFString autoreleased with no pool in place - just leaking 2009-10-14 17:17:54.092 java[2010:10003] *** __NSAutoreleaseNoPool(): Object 0x101624540 of class NSCFData autoreleased with no pool in place - just leaking . . . I've used the -XstartOnFirstThread VM argument without any luck. I'm on 64-bit Cocoa but I've also tried 32-bit Cocoa. When trying on Carbon I get the following error: Invalid memory access of location 00000020 eip=9012337c When debugging into the Display class I can see that the Displays[] array only contains null references.

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• Java Performance measurement

  - by portoalet

  Hi, I am doing some Java performance comparison between my classes, and wondering if there is some sort of Java Performance Framework to make writing performance measurement code easier? I.e, what I am doing now is trying to measure what effect does it have having a method as "synchronized" as in PseudoRandomUsingSynch.nextInt() compared to using an AtomicInteger as my "synchronizer". So I am trying to measure how long it takes to generate random integers using 3 threads accessing a synchronized method looping for say 10000 times. I am sure there is a much better way doing this. Can you please enlighten me? :) public static void main( String [] args ) throws InterruptedException, ExecutionException { PseudoRandomUsingSynch rand1 = new PseudoRandomUsingSynch((int)System.currentTimeMillis()); int n = 3; ExecutorService execService = Executors.newFixedThreadPool(n); long timeBefore = System.currentTimeMillis(); for(int idx=0; idx<100000; ++idx) { Future<Integer> future = execService.submit(rand1); Future<Integer> future1 = execService.submit(rand1); Future<Integer> future2 = execService.submit(rand1); int random1 = future.get(); int random2 = future1.get(); int random3 = future2.get(); } long timeAfter = System.currentTimeMillis(); long elapsed = timeAfter - timeBefore; out.println("elapsed:" + elapsed); } the class public class PseudoRandomUsingSynch implements Callable<Integer> { private int seed; public PseudoRandomUsingSynch(int s) { seed = s; } public synchronized int nextInt(int n) { byte [] s = DonsUtil.intToByteArray(seed); SecureRandom secureRandom = new SecureRandom(s); return ( secureRandom.nextInt() % n ); } @Override public Integer call() throws Exception { return nextInt((int)System.currentTimeMillis()); } } Regards

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• Java - SwingWorker - problem

  - by Yatendra Goel

  I am developing a Java Desktop Application. This app executes the same task public class MyTask implements Callable<MyObject> { in multiple thread simultaneously. Now, when a user clicks on a "start" button, I have created a SwingWorker myWorker and have executed it. Now, this myWorker creates multiple instances of MyTask and submits them to an ExecutorService. Each MyTask instance has a loop and generates an intermediate result at every iteration. Now, I want to collect these intermediate results from each MyTask instances as soon as they are generated. Then after collecting these intermediate results from every MyTask instance, I want to publish it through SwingWorker.publish(MyObject) so that the progress is shown on the EDT. Q1. How can I implement this? Should I make MyTask subclass of SwingWorker instead of Callable to get intermediate results also, because I think that Callable only returns final result. Q2. If the answer of Q1. is yes, then can you give me a small example to show how can I get those intermediate results and aggregate them and then publish them from main SwingWorker? Q3. If I can't use SwingWorker in this situation, then how can I implement this?

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• When does the call() method get called in a Java Executor using Callable objects?

  - by MalcomTucker

  This is some sample code from an example. What I need to know is when call() gets called on the callable? What triggers it? public class CallableExample { public static class WordLengthCallable implements Callable { private String word; public WordLengthCallable(String word) { this.word = word; } public Integer call() { return Integer.valueOf(word.length()); } } public static void main(String args[]) throws Exception { ExecutorService pool = Executors.newFixedThreadPool(3); Set<Future<Integer>> set = new HashSet<Future<Integer>>(); for (String word: args) { Callable<Integer> callable = new WordLengthCallable(word); Future<Integer> future = pool.submit(callable); //**DOES THIS CALL call()?** set.add(future); } int sum = 0; for (Future<Integer> future : set) { sum += future.get();//**OR DOES THIS CALL call()?** } System.out.printf("The sum of lengths is %s%n", sum); System.exit(sum); } }

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• Strange problem with simple multithreading program in Java

  - by Elizabeth

  Hello, I am just starting play with multithreading programming. I would like to my program show alternately character '-' and '+' but it doesn't. My task is to use synchronized keyword. As far I have: class FunnyStringGenerator{ private char c; public FunnyStringGenerator(){ c = '-'; } public synchronized char next(){ if(c == '-'){ c = '+'; } else{ c = '-'; } return c; } } class ThreadToGenerateStr implements Runnable{ FunnyStringGenerator gen; public ThreadToGenerateStr(FunnyStringGenerator fsg){ gen = fsg; } @Override public void run() { for(int i = 0; i < 10; i++){ System.out.print(gen.next()); } } } public class Main{ public static void main(String[] args) throws IOException { FunnyStringGenerator FSG = new FunnyStringGenerator(); ExecutorService exec = Executors.newCachedThreadPool(); for(int i = 0; i < 20; i++){ exec.execute(new ThreadToGenerateStr(FSG)); } } } EDIT: I also testing Thread.sleep in run method instead for loop.

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• How to drop/restart a client connection to a flaky socket server

  - by Steve Prior

  I've got Java code which makes requests via sockets from a server written in C++. The communication is simply that the java code writes a line for a request and the server then writes a line in response, but sometimes it seems that the server doesn't respond, so I've implemented an ExecutorService based timeout which tries to drop and restart the connection. To work with the connection I keep: Socket server; PrintWriter out; BufferedReader in; so setting up the connection is a matter of: server = new Socket(hostname, port); out = new PrintWriter(new OutputStreamWriter(server.getOutputStream())); in = new BufferedReader(new InputStreamReader(socket.getInputStream())); If it weren't for the timeout code the request/receive steps are simply: String request="some request"; out.println(request); out.flush(); String response = in.readLine(); When I received a timeout I was trying to close the connection with: in.close(); out.close(); socket.close(); but one of these closes seems to block and never return. Can anyone give me a clue why one of these would block and what would be the proper way to abandon the connection and not end up with resource leak issues?

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• Threads syncronization with ThreadPoolExecutor

  - by justme1

  I'm trying to implement some logic when I create main(father) thread witch executes several other threads. Then it waits for some condition which child threads creates. After condition is meet the father executes some more child threads. The problem that when I use wait/notify I have java.lang.IllegalMonitorStateException exception. Here is the code: public class MyExecutor { final static ArrayBlockingQueue<Runnable> queue = new ArrayBlockingQueue<Runnable>(10); final static ExecutorService svc = Executors.newFixedThreadPool(1); static final ThreadPoolExecutor threadPool = new ThreadPoolExecutor(5, 8, 10, TimeUnit.SECONDS, queue); public static void main(String[] args) throws InterruptedException { final MyExecutor me = new MyExecutor(); svc.execute(new Runnable() { public void run() { try { System.out.println("Main Thread"); me.execute(threadPool, 1); System.out.println("Main Thread waiting"); wait(); System.out.println("Main Thread notified"); me.execute(threadPool, 2); Thread.sleep(100); threadPool.shutdown(); threadPool.awaitTermination(20000, TimeUnit.SECONDS); } catch (InterruptedException e) { e.printStackTrace(); } } }); svc.shutdown(); svc.awaitTermination(10000, TimeUnit.SECONDS); System.out.println("Main Thread finished"); } public void execute(ThreadPoolExecutor tpe, final int id) { tpe.execute(new Runnable() { public void run() { try { System.out.println("Child Thread " + id); Thread.sleep(2000); System.out.println("Child Thread " + id + " finished"); notify(); } catch (InterruptedException e) { e.printStackTrace(); } } }); } } When I comment wait and notify line I have the following output: Main Thread Main Thread waiting Main Thread notified Child Thread 1 Child Thread 2 Child Thread 1 finished Child Thread 2 finished Main Thread finished

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• Concurrency Utilities for Java EE Early Draft (JSR 236)

  - by arungupta

  Concurrency Utilities for Java EE is being worked as JSR 236 and has released an Early Draft. It provides concurrency capabilities to Java EE application components without compromising container integrity. Simple (common) and advanced concurrency patterns are easily supported without sacrificing usability. Using Java SE concurrency utilities such as java.util.concurrent API, java.lang.Thread and java.util.Timer in a Java EE application component such as EJB or Servlet are problematic since the container and server have no knowledge of these resources. JSR 236 enables concurrency largely by extending the Concurrency Utilities API developed under JSR-166. This also allows a consistency between Java SE and Java EE concurrency programming model. There are four main programming interfaces available: ManagedExecutorService ManagedScheduledExecutorService ContextService ManagedThreadFactory ManagedExecutorService is a managed version of java.util.concurrent.ExecutorService. The implementations of this interface are provided by the container and accessible using JNDI reference: <resource-env-ref>  <resource-env-ref-name>    concurrent/BatchExecutor  </resource-env-ref-name>  <resource-env-ref-type>    javax.enterprise.concurrent.ManagedExecutorService  </resource-env-ref-type><resource-env-ref> and available as: @Resource(name="concurrent/BatchExecutor")ManagedExecutorService executor; Its recommended to bind the JNDI references in the java:comp/env/concurrent subcontext. The asynchronous tasks that need to be executed need to implement java.lang.Runnable or java.util.concurrent.Callable interface as: public class MyTask implements Runnable { public void run() { // business logic goes here }} OR public class MyTask2 implements Callable<Date> {  public Date call() { // business logic goes here   }} The task is then submitted to the executor using one of the submit method that return a Future instance. The Future represents the result of the task and can also be used to check if the task is complete or wait for its completion. Future<String> future = executor.submit(new MyTask(), String.class);. . .String result = future.get(); Another example to submit tasks is: class MyTask implements Callback<Long> { . . . }class MyTask2 implements Callback<Date> { . . . }ArrayList<Callable> tasks = new ArrayList<();tasks.add(new MyTask());tasks.add(new MyTask2());List<Future<Object>> result = executor.invokeAll(tasks); The ManagedExecutorService may be configured for different properties such as: Hung Task Threshold: Time in milliseconds that a task can execute before it is considered hung Pool Info Core Size: Number of threads to keep alive Maximum Size: Maximum number of threads allowed in the pool Keep Alive: Time to allow threads to remain idle when # of threads > Core Size Work Queue Capacity: # of tasks that can be stored in inbound buffer Thread Use: Application intend to run short vs long-running tasks, accordingly pooled or daemon threads are picked ManagedScheduledExecutorService adds delay and periodic task running capabilities to ManagedExecutorService. The implementations of this interface are provided by the container and accessible using JNDI reference: <resource-env-ref>  <resource-env-ref-name>    concurrent/BatchExecutor  </resource-env-ref-name>  <resource-env-ref-type>    javax.enterprise.concurrent.ManagedExecutorService  </resource-env-ref-type><resource-env-ref> and available as: @Resource(name="concurrent/timedExecutor")ManagedExecutorService executor; And then the tasks are submitted using submit, invokeXXX or scheduleXXX methods. ScheduledFuture<?> future = executor.schedule(new MyTask(), 5, TimeUnit.SECONDS); This will create and execute a one-shot action that becomes enabled after 5 seconds of delay. More control is possible using one of the newly added methods: MyTaskListener implements ManagedTaskListener {  public void taskStarting(...) { . . . }  public void taskSubmitted(...) { . . . }  public void taskDone(...) { . . . }  public void taskAborted(...) { . . . } }ScheduledFuture<?> future = executor.schedule(new MyTask(), 5, TimeUnit.SECONDS, new MyTaskListener()); Here, ManagedTaskListener is used to monitor the state of a task's future. ManagedThreadFactory provides a method for creating threads for execution in a managed environment. A simple usage is: @Resource(name="concurrent/myThreadFactory")ManagedThreadFactory factory;. . .Thread thread = factory.newThread(new Runnable() { . . . }); concurrent/myThreadFactory is a JNDI resource. There is lot of interesting content in the Early Draft, download it, and read yourself. The implementation will be made available soon and also be integrated in GlassFish 4 as well. Some references for further exploring ... Javadoc Early Draft Specification concurrency-ee-spec.java.net [email protected]

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• Java Synchronized List Deadlock

  - by portoalet

  From Effective Java 2nd edition item 67 page 266-268: The background thread calls s.removeObserver, which attempts to lock observers, but it can’t acquire the lock, because the main thread already has the lock. All the while, the main thread is waiting for the background thread to finish removing the observer, which explains the deadlock. I am trying to find out which threads deadlock in the main method by using ThreadMXBean (http://stackoverflow.com/questions/1102359/programmatic-deadlock-detection-in-java) , but why does it not return the deadlocked threads? I used a new Thread to run the ThreadMXBean detection. public class ObservableSet<E> extends ForwardingSet<E> { public ObservableSet(Set<E> set) { super(set); } private final List<SetObserver<E>> observers = new ArrayList<SetObserver<E>>(); public void addObserver(SetObserver<E> observer) { synchronized(observers) { observers.add(observer); } } public boolean removeObserver(SetObserver<E> observer) { synchronized(observers) { return observers.remove(observer); } } private void notifyElementAdded(E element) { synchronized(observers) { for (SetObserver<E> observer : observers) observer.added(this, element); } } @Override public boolean add(E element) { boolean added = super.add(element); if (added) notifyElementAdded(element); return added; } @Override public boolean addAll(Collection<? extends E> c) { boolean result = false; for (E element : c) result|=add(element); //callsnotifyElementAdded return result; } public static void main(String[] args) { ObservableSet<Integer> set = new ObservableSet<Integer>(new HashSet<Integer>()); final ThreadMXBean threadMxBean = ManagementFactory.getThreadMXBean(); Thread t = new Thread(new Runnable() { @Override public void run() { while( true ) { long [] threadIds = threadMxBean.findDeadlockedThreads(); if( threadIds != null) { ThreadInfo[] infos = threadMxBean.getThreadInfo(threadIds); for( ThreadInfo threadInfo : infos) { StackTraceElement[] stacks = threadInfo.getStackTrace(); for( StackTraceElement stack : stacks ) { System.out.println(stack.toString()); } } } try { System.out.println("Sleeping.."); TimeUnit.MILLISECONDS.sleep(1000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } }); t.start(); set.addObserver(new SetObserver<Integer>() { public void added(ObservableSet<Integer> s, Integer e) { ExecutorService executor = Executors.newSingleThreadExecutor(); final SetObserver<Integer> observer = this; try { executor.submit(new Runnable() { public void run() { s.removeObserver(observer); } }).get(); } catch (ExecutionException ex) { throw new AssertionError(ex.getCause()); } catch (InterruptedException ex) { throw new AssertionError(ex.getCause()); } finally { executor.shutdown(); } } }); for (int i = 0; i < 100; i++) set.add(i); } } public interface SetObserver<E> { // Invoked when an element is added to the observable set void added(ObservableSet<E> set, E element); } // ForwardingSet<E> simply wraps another Set and forwards all operations to it.

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• parallel computation for an Iterator of elements in Java

  - by Brian Harris

  I've had the same need a few times now and wanted to get other thoughts on the right way to structure a solution. The need is to perform some operation on many elements on many threads without needing to have all elements in memory at once, just the ones under computation. As in, Iterables.partition is insufficient because it brings all elements into memory up front. Expressing it in code, I want to write a BulkCalc2 that does the same thing as BulkCalc1, just in parallel. Below is sample code that illustrates my best attempt. I'm not satisfied because it's big and ugly, but it does seem to accomplish my goals of keeping threads highly utilized until the work is done, propagating any exceptions during computation, and not having more than numThreads instances of BigThing necessarily in memory at once. I'll accept the answer which meets the stated goals in the most concise way, whether it's a way to improve my BulkCalc2 or a completely different solution. interface BigThing { int getId(); String getString(); } class Calc { // somewhat expensive computation double calc(BigThing bigThing) { Random r = new Random(bigThing.getString().hashCode()); double d = 0; for (int i = 0; i < 100000; i++) { d += r.nextDouble(); } return d; } } class BulkCalc1 { final Calc calc; public BulkCalc1(Calc calc) { this.calc = calc; } public TreeMap<Integer, Double> calc(Iterator<BigThing> in) { TreeMap<Integer, Double> results = Maps.newTreeMap(); while (in.hasNext()) { BigThing o = in.next(); results.put(o.getId(), calc.calc(o)); } return results; } } class SafeIterator<T> { final Iterator<T> in; SafeIterator(Iterator<T> in) { this.in = in; } synchronized T nextOrNull() { if (in.hasNext()) { return in.next(); } return null; } } class BulkCalc2 { final Calc calc; final int numThreads; public BulkCalc2(Calc calc, int numThreads) { this.calc = calc; this.numThreads = numThreads; } public TreeMap<Integer, Double> calc(Iterator<BigThing> in) { ExecutorService e = Executors.newFixedThreadPool(numThreads); List<Future<?>> futures = Lists.newLinkedList(); final Map<Integer, Double> results = new MapMaker().concurrencyLevel(numThreads).makeMap(); final SafeIterator<BigThing> it = new SafeIterator<BigThing>(in); for (int i = 0; i < numThreads; i++) { futures.add(e.submit(new Runnable() { @Override public void run() { while (true) { BigThing o = it.nextOrNull(); if (o == null) { return; } results.put(o.getId(), calc.calc(o)); } } })); } e.shutdown(); for (Future<?> future : futures) { try { future.get(); } catch (InterruptedException ex) { // swallowing is OK } catch (ExecutionException ex) { throw Throwables.propagate(ex.getCause()); } } return new TreeMap<Integer, Double>(results); } }

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• Concurrency and Calendar classes

  - by fbielejec

  I have a thread (class implementing runnable, called AnalyzeTree) organised around a hash map (ConcurrentMap slicesMap). The class goes through the data (called trees here) in the large text file and parses the geographical coordinates from it to the HashMap. The idea is to process one tree at a time and add or grow the values according to the key (which is just a Double value representing time). The relevant part of code looks like this: // grow map entry if key exists if (slicesMap.containsKey(sliceTime)) { double[] imputedLocation = imputeValue( location, parentLocation, sliceHeight, nodeHeight, parentHeight, rate, useTrueNoise, currentTreeNormalization, precisionArray); slicesMap.get(sliceTime).add( new Coordinates(imputedLocation[1], imputedLocation[0], 0.0)); // start new entry if no such key in the map } else { List<Coordinates> coords = new ArrayList<Coordinates>(); double[] imputedLocation = imputeValue( location, parentLocation, sliceHeight, nodeHeight, parentHeight, rate, useTrueNoise, currentTreeNormalization, precisionArray); coords.add(new Coordinates(imputedLocation[1], imputedLocation[0], 0.0)); slicesMap.putIfAbsent(sliceTime, coords); // slicesMap.put(sliceTime, coords); }// END: key check And the class is called like this (executor is ExecutorService executor = Executors.newFixedThreadPool(NTHREDS) ): mrsd = new SpreadDate(mrsdString); int readTrees = 1; while (treesImporter.hasTree()) { currentTree = (RootedTree) treesImporter.importNextTree(); executor.submit(new AnalyzeTree(currentTree, precisionString, coordinatesName, rateString, numberOfIntervals, treeRootHeight, timescaler, mrsd, slicesMap, useTrueNoise)); // new AnalyzeTree(currentTree, precisionString, // coordinatesName, rateString, numberOfIntervals, // treeRootHeight, timescaler, mrsd, slicesMap, // useTrueNoise).run(); readTrees++; }// END: while has trees Now this is running into troubles when executed in parallel (the commented part running sequentially is fine), I thought it might throw a ConcurrentModificationException, but apparently the problem is in mrsd (instance of SpreadDate object, which is simply a class for date related calculations). The SpreadDate class looks like this: public class SpreadDate { private Calendar cal; private SimpleDateFormat formatter; private Date stringdate; public SpreadDate(String date) throws ParseException { // if no era specified assume current era String line[] = date.split(" "); if (line.length == 1) { StringBuilder properDateStringBuilder = new StringBuilder(); date = properDateStringBuilder.append(date).append(" AD") .toString(); } formatter = new SimpleDateFormat("yyyy-MM-dd G", Locale.US); stringdate = formatter.parse(date); cal = Calendar.getInstance(); } public long plus(int days) { cal.setTime(stringdate); cal.add(Calendar.DATE, days); return cal.getTimeInMillis(); }// END: plus public long minus(int days) { cal.setTime(stringdate); cal.add(Calendar.DATE, -days); //line 39 return cal.getTimeInMillis(); }// END: minus public long getTime() { cal.setTime(stringdate); return cal.getTimeInMillis(); }// END: getDate } And the stack trace from when exception is thrown: java.lang.ArrayIndexOutOfBoundsException: 58 at sun.util.calendar.BaseCalendar.getCalendarDateFromFixedDate(BaseCalendar.java:454) at java.util.GregorianCalendar.computeFields(GregorianCalendar.java:2098) at java.util.GregorianCalendar.computeFields(GregorianCalendar.java:2013) at java.util.Calendar.setTimeInMillis(Calendar.java:1126) at java.util.GregorianCalendar.add(GregorianCalendar.java:1020) at utils.SpreadDate.minus(SpreadDate.java:39) at templates.AnalyzeTree.run(AnalyzeTree.java:88) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334) at java.util.concurrent.FutureTask.run(FutureTask.java:166) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) at java.lang.Thread.run(Thread.java:636) If a move the part initializing mrsd to the AnalyzeTree class it runs without any problems - however it is not very memory efficient to initialize class each time this thread is running, hence my concerns. How can it be remedied?

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• OIM 11g : Multi-thread approach for writing custom scheduled job

  - by Saravanan V S

  In this post I have shared my experience of designing and developing an OIM schedule job that uses multi threaded approach for updating data in OIM using APIs.  I have used thread pool (in particular fixed thread pool) pattern in developing the OIM schedule job. The thread pooling pattern has noted advantages compared to thread per task approach. I have listed few of the advantage here ·         Threads are reused ·         Creation and tear-down cost of thread is reduced ·         Task execution latency is reduced ·         Improved performance ·         Controlled and efficient management of memory and resources used by threads More about java thread pool http://docs.oracle.com/javase/tutorial/essential/concurrency/pools.html The following diagram depicts the high-level architectural diagram of the schedule job that process input from a flat file to update OIM process form data using fixed thread pool approach    The custom scheduled job shared in this post is developed to meet following requirement 1)      Need to process a CSV extract that contains identity, account identifying key and list of data to be updated on an existing OIM resource account. 2)      CSV file can contain data for multiple resources configured in OIM 3)      List of attribute to update and mapping between CSV column to OIM fields may vary between resources The following are three Java class developed for this requirement (I have given only prototype of the code that explains how to use thread pools in schedule task) CustomScheduler.java - Implementation of TaskSupport class that reads and passes the parameters configured on the schedule job to Thread Executor class. package com.oracle.oim.scheduler; import java.util.HashMap; import com.oracle.oim.bo.MultiThreadDataRecon; import oracle.iam.scheduler.vo.TaskSupport; public class CustomScheduler extends TaskSupport {      public void execute(HashMap options) throws Exception {             /*  Read Schedule Job Parameters */             String param1 = (String) options.get(“Parameter1”);             .             int noOfThread = (int) options.get(“No of Threads”);             .             String paramn = (int) options.get(“ParamterN”); /* Provide all the required input configured on schedule job to Thread Pool Executor implementation class like 1) Name of the file, 2) Delimiter 3) Header Row Numer 4) Line Escape character 5) Config and resource map lookup 6) No the thread to create */ new MultiThreadDataRecon(all_required_parameters, noOfThreads).reconcile();       }       public HashMap getAttributes() { return null; }       public void setAttributes() {       } } MultiThreadDataRecon.java – Helper class that reads data from input file, initialize the thread executor and builds the task queue. package com.oracle.oim.bo; import <required file IO classes>; import  <required java.util classes>; import  <required OIM API classes>; import <csv reader api>; public class MultiThreadDataRecon {  private int noOfThreads;  private ExecutorService threadExecutor = null;  public MetaDataRecon(<required params>, int noOfThreads)  {       //Store parameters locally       .       .       this.noOfThread = noOfThread;  }        /**        *  Initialize         */  private void init() throws Exception {       try {             // Initialize CSV file reader API objects             // Initialize OIM API objects             /* Initialize Fixed Thread Pool Executor class if no of threads                 configured is more than 1 */             if (noOfThreads > 1) {                   threadExecutor = Executors.newFixedThreadPool(noOfThreads);             } else {                   threadExecutor = Executors.newSingleThreadExecutor();             }             /* Initialize TaskProcess clas s which will be executing task                 from the Queue */                TaskProcessor.initializeConfig(params);       } catch (***Exception e) {                   // TO DO       }  }       /**        *  Method to reconcile data from CSV to OIM        */ public void reconcile() throws Exception {        try {             init();             while(<csv file has line>){                   processRow(line);             }             /* Initiate thread shutdown */             threadExecutor.shutdown();             while (!threadExecutor.isTerminated()) {                 // Wait for all task to complete.             }            } catch (Exception e) {                   // TO DO            } finally {                   try {                         //Close all the file handles                   } catch (IOException e) {                         //TO DO                   }             }       }       /**        * Method to process         */       private void processRow(String row) {             // Create task processor instance with the row data              // Following code push the task to work queue and wait for next                available thread to execute             threadExecutor.execute(new TaskProcessor(rowData));       } } TaskProcessor.java – Implementation of “Runnable” interface that executes the required business logic to update data in OIM. package com.oracle.oim.bo; import <required APIs> class TaskProcessor implements Runnable {       //Initialize required member variables       /**        * Constructor        */       public TaskProcessor(<row data>) {             // Initialize and parse csv row       }       /*       *  Method to initialize required object for task execution       */       public static void initializeConfig(<params>) {             // Process param and initialize the required configs and object       }           /*        * (non-Javadoc)        *         * @see java.lang.Runnable#run()        */            public void run() {             if (<is csv data valid>){                   processData();             }       }  /**   * Process the the received CSV input   */  private void processData() {     try{       //Find the user in OIM using the identity matching key value from CSV       // Find the account to be update from user’s account based on account identifying key on CSV       // Update the account with data from CSV       }catch(***Exception e){           //TO DO       }   } }

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• How do I get spring to inject my EntityManager?

  - by Trampas Kirk

  I'm following the guide here, but when the DAO executes, the EntityManager is null. I've tried a number of fixes I found in the comments on the guide, on various forums, and here (including this), to no avail. No matter what I seem to do the EntityManager remains null. Here are the relevant files, with packages etc changed to protect the innocent. spring-context.xml <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd" xmlns:p="http://www.springframework.org/schema/p"> <context:component-scan base-package="com.group.server"/> <context:annotation-config/> <tx:annotation-driven/> <bean id="propertyPlaceholderConfigurer" class="com.group.DecryptingPropertyPlaceholderConfigurer" p:systemPropertiesModeName="SYSTEM_PROPERTIES_MODE_OVERRIDE"> <property name="locations"> <list> <value>classpath*:spring-*.properties</value> <value>classpath*:${application.environment}.properties</value> </list> </property> </bean> <bean id="orderDao" class="com.package.service.OrderDaoImpl"/> <bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor"/> <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="persistenceUnitName" value="MyServer"/> <property name="loadTimeWeaver"> <bean class="org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver"/> </property> <property name="dataSource" ref="dataSource"/> <property name="jpaVendorAdapter"> <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"> <property name="showSql" value="${com.group.server.vendoradapter.showsql}"/> <property name="generateDdl" value="${com.group.server.vendoradapter.generateDdl}"/> <property name="database" value="${com.group.server.vendoradapter.database}"/> </bean> </property> </bean> <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"> <property name="entityManagerFactory" ref="entityManagerFactory"/> <property name="dataSource" ref="dataSource"/> </bean> <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="driverClassName" value="${com.group.server.datasource.driverClassName}"/> <property name="url" value="${com.group.server.datasource.url}"/> <property name="username" value="${com.group.server.datasource.username}"/> <property name="password" value="${com.group.server.datasource.password}"/> </bean> <bean id="executorService" class="java.util.concurrent.Executors" factory-method="newCachedThreadPool"/> </beans> persistence.xml <persistence xmlns="http://java.sun.com/xml/ns/persistence" version="1.0"> <persistence-unit name="MyServer" transaction-type="RESOURCE_LOCAL"/> </persistence> OrderDaoImpl package com.group.service; import com.group.model.Order; import org.springframework.stereotype.Repository; import org.springframework.transaction.annotation.Transactional; import javax.persistence.EntityManager; import javax.persistence.PersistenceContext; import javax.persistence.Query; import java.util.List; @Repository @Transactional public class OrderDaoImpl implements OrderDao { private EntityManager entityManager; @PersistenceContext public void setEntityManager(EntityManager entityManager) { this.entityManager = entityManager; } @Override public Order find(Integer id) { Order order = entityManager.find(Order.class, id); return order; } @Override public List<Order> findAll() { Query query = entityManager.createQuery("select o from Order o"); return query.getResultList(); } @Override public List<Order> findBySymbol(String symbol) { Query query = entityManager.createQuery("select o from Order o where o.symbol = :symbol"); return query.setParameter("symbol", symbol).getResultList(); } }

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