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  • Lua API for TokyoTyrant

    - by jideel
    Hi SO folks, I didn't managed to find an Lua client/api for TokyoTyrant. Such Api exists for TokyoCabinet, but not for TT. And Perl and Ruby API exists for TT. TT provides a native binary protocol, a memcached-compatible protocol, and an HTTP-oriented protocol. So my questions are : 1/ Do you think using the memcached (using luamemcached) or the HTTP protocol (using luaSocket) is "enough" for most / simple usage, and so a native Lua api is not necessary ? (the app is a simple uuid storage/distributor) ? 2/ Does it make sense to not use TokyoTyrant, but only TokyoCabinet, and use Lua at the application level to provide network and concurrent access to TC, using, say, Copas (Copas is , from their website, "a dispatcher based on coroutines that can be used by TCP/IP servers." ? Thanks.

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  • SqlServer / MySql Connection pool: is it really important ?

    - by stighy
    Hy guys, after a lot of problem with my hoster, i decided to disable connection pooling of my application. The problem was related to the number of concurrent connections : only five. So i decided to disable connection pooling: the result is that my web app don't crash. So i'm asking you: are there some "collateral" effect disabling connection pooling ? Is it so important ? I didn't noticed bad performance after disabling it. Thank you for your (i'm sure) precious advice!

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  • Light-weight client/server DB?

    - by OverTheRainbow
    Hello, (This question falls between programming and finding a tool, so I guess I'll ask here in SO since it has more activity than SuperUser.) I like the simplicity of SQLite, but by design, it doesn't support concurrent access. The apps I write don't have heavy needs, so I'd like to avoid heavier solutions like MySQL that are more difficult to deploy (remote customers with usually no computer personnel). Does someone know of a good solution that would offer the following features? Client available for VB.Net applications The server itself doesn't have to be a .Net application. Actually, I'd rather a bare-metal server so that it can run even on embedded Linux hosts with less RAM/CPU than regular PC's Easy install: the client part should either be statically linked inside the client application or be available as a single DLL, and the server should just be a single EXE listening for queries, à la Fossil (http://www.fossil-scm.org) clients can locate the server on the LAN by broadcasting data picked up by the server, so users don't have to write down the IP address and paste it into each client open-source, or moderately priced closed-source Thank you.

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  • Haskell typeclass

    - by Geoff
    I have a Haskell typeclass question. I can't munge the syntax to get this (seemingly reasonable) program to compile under GHC. import Control.Concurrent.MVar blah1 :: [a] -> IO ([a]) blah1 = return blah2 :: [a] -> IO (MVar [a]) blah2 = newMVar class Blah b where blah :: [a] -> IO (b a) instance Blah [] where blah = blah1 -- BOOM instance Blah (MVar []) where blah = blah2 main :: IO () main = do putStrLn "Ok" I get the following error message, which kind of makes sense, but I don't know how to fix it: `[]' is not applied to enough type arguments Expected kind `*', but `[]' has kind `* -> *' In the type `MVar []' In the instance declaration for `Blah (MVar [])'

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  • Java - JPA - When we need more than one EntityManager?

    - by Yatendra Goel
    I am learning JPA and have one question: In which situations we need more than one EntityManager in our application? The two situations that I am aware of are as follows: When our application is a multi-threaded application and more than one thread needs JPA transaction because EntityManager is not thread-safe and we need one EntityManager per thread. When any of the thread needs multiple concurrent transactions, we need more than one EntityManager in that thread because there is one-to-one relationship between EntityManager and EntityTransaction. Q1. Are there any other situations when we need more than one EntityManager? ================================================================================= Q2. Upto my understanding, there should be only one EntityManagerFactory per Persitence Unit. Am I correct? If not, then what are those situations when we need multiple EntityManagerFactory per Persistence Unit?

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  • Node.js vs PHP processing speed

    - by Cody Craven
    I've been looking into node.js recently and wanted to see a true comparison of processing speed for PHP vs Node.js. In most of the comparisons I had seen, Node trounced Apache/PHP set ups handily. However all of the tests were small 'hello worlds' that would not accurately reflect any webpage's markup. So I decided to create a basic HTML page with 10,000 hello world paragraph elements. In these tests Node with Cluster was beaten to a pulp by PHP on Nginx utilizing PHP-FPM. So I'm curious if I am misusing Node somehow or if Node is really just this bad at processing power. Note that my results were equivalent outputting "Hello world\n" with text/plain as the HTML, but I only included the HTML as it's closer to the use case I was investigating. My testing box: Core i7-2600 Intel CPU (has 8 threads with 4 cores) 8GB DDR3 RAM Fedora 16 64bit Node.js v0.6.13 Nginx v1.0.13 PHP v5.3.10 (with PHP-FPM) My test scripts: Node.js script var cluster = require('cluster'); var http = require('http'); var numCPUs = require('os').cpus().length; if (cluster.isMaster) { // Fork workers. for (var i = 0; i < numCPUs; i++) { cluster.fork(); } cluster.on('death', function (worker) { console.log('worker ' + worker.pid + ' died'); }); } else { // Worker processes have an HTTP server. http.Server(function (req, res) { res.writeHead(200, {'Content-Type': 'text/html'}); res.write('<html>\n<head>\n<title>Speed test</title>\n</head>\n<body>\n'); for (var i = 0; i < 10000; i++) { res.write('<p>Hello world</p>\n'); } res.end('</body>\n</html>'); }).listen(80); } This script is adapted from Node.js' documentation at http://nodejs.org/docs/latest/api/cluster.html PHP script <?php echo "<html>\n<head>\n<title>Speed test</title>\n</head>\n<body>\n"; for ($i = 0; $i < 10000; $i++) { echo "<p>Hello world</p>\n"; } echo "</body>\n</html>"; My results Node.js $ ab -n 500 -c 20 http://speedtest.dev/ This is ApacheBench, Version 2.3 <$Revision: 655654 $> Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/ Licensed to The Apache Software Foundation, http://www.apache.org/ Benchmarking speedtest.dev (be patient) Completed 100 requests Completed 200 requests Completed 300 requests Completed 400 requests Completed 500 requests Finished 500 requests Server Software: Server Hostname: speedtest.dev Server Port: 80 Document Path: / Document Length: 190070 bytes Concurrency Level: 20 Time taken for tests: 14.603 seconds Complete requests: 500 Failed requests: 0 Write errors: 0 Total transferred: 95066500 bytes HTML transferred: 95035000 bytes Requests per second: 34.24 [#/sec] (mean) Time per request: 584.123 [ms] (mean) Time per request: 29.206 [ms] (mean, across all concurrent requests) Transfer rate: 6357.45 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 0 0 0.2 0 2 Processing: 94 547 405.4 424 2516 Waiting: 0 331 399.3 216 2284 Total: 95 547 405.4 424 2516 Percentage of the requests served within a certain time (ms) 50% 424 66% 607 75% 733 80% 813 90% 1084 95% 1325 98% 1843 99% 2062 100% 2516 (longest request) PHP/Nginx $ ab -n 500 -c 20 http://speedtest.dev/test.php This is ApacheBench, Version 2.3 <$Revision: 655654 $> Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/ Licensed to The Apache Software Foundation, http://www.apache.org/ Benchmarking speedtest.dev (be patient) Completed 100 requests Completed 200 requests Completed 300 requests Completed 400 requests Completed 500 requests Finished 500 requests Server Software: nginx/1.0.13 Server Hostname: speedtest.dev Server Port: 80 Document Path: /test.php Document Length: 190070 bytes Concurrency Level: 20 Time taken for tests: 0.130 seconds Complete requests: 500 Failed requests: 0 Write errors: 0 Total transferred: 95109000 bytes HTML transferred: 95035000 bytes Requests per second: 3849.11 [#/sec] (mean) Time per request: 5.196 [ms] (mean) Time per request: 0.260 [ms] (mean, across all concurrent requests) Transfer rate: 715010.65 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 0 0 0.2 0 1 Processing: 3 5 0.7 5 7 Waiting: 1 4 0.7 4 7 Total: 3 5 0.7 5 7 Percentage of the requests served within a certain time (ms) 50% 5 66% 5 75% 5 80% 6 90% 6 95% 6 98% 6 99% 6 100% 7 (longest request) Additional details Again what I'm looking for is to find out if I'm doing something wrong with Node.js or if it is really just that slow compared to PHP on Nginx with FPM. I certainly think Node has a real niche that it could fit well, however with these test results (which I really hope I made a mistake with - as I like the idea of Node) lead me to believe that it is a horrible choice for even a modest processing load when compared to PHP (let alone JVM or various other fast solutions). As a final note, I also tried running an Apache Bench test against node with $ ab -n 20 -c 20 http://speedtest.dev/ and consistently received a total test time of greater than 0.900 seconds.

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  • Spring App error: java.lang.NoClassDefFoundError: org/springframework/security/core/SpringSecurityCoreVersion

    - by Shades88
    I am writing a simple spring mvc login form example. I am getting below error in netbeans 05-Jun-2014 02:11:51.055 SEVERE [http-nio-8084-exec-1] org.apache.catalina.core.StandardContext.listenerStart Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener org.springframework.beans.factory.BeanDefinitionStoreException: Unexpected exception parsing XML document from ServletContext resource [/WEB-INF/SpringSecurity.xml]; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [org.springframework.security.config.SecurityNamespaceHandler]: Constructor threw exception; nested exception is java.lang.NoClassDefFoundError: org/springframework/security/core/SpringSecurityCoreVersion at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:413) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:335) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:303) at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:180) at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:216) at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:187) at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:125) at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:94) at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:129) at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:540) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:454) at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:403) at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:306) at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:106) at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4738) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5158) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:726) at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:702) at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:697) at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:579) at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:455) at org.apache.catalina.startup.HostConfig.check(HostConfig.java:1554) at sun.reflect.GeneratedMethodAccessor53.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:300) at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819) at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801) at org.apache.catalina.manager.ManagerServlet.check(ManagerServlet.java:1428) at org.apache.catalina.manager.ManagerServlet.deploy(ManagerServlet.java:885) at org.apache.catalina.manager.ManagerServlet.doGet(ManagerServlet.java:343) at javax.servlet.http.HttpServlet.service(HttpServlet.java:618) at javax.servlet.http.HttpServlet.service(HttpServlet.java:725) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:301) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.filters.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:108) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:615) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:136) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:74) at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:516) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1015) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:652) at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:222) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1575) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1533) 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:744) Caused by: org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [org.springframework.security.config.SecurityNamespaceHandler]: Constructor threw exception; nested exception is java.lang.NoClassDefFoundError: org/springframework/security/core/SpringSecurityCoreVersion at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:164) at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:105) at org.springframework.beans.factory.xml.DefaultNamespaceHandlerResolver.resolve(DefaultNamespaceHandlerResolver.java:130) at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1419) at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1414) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:187) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:141) at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:110) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:508) at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:391) ... 60 more Caused by: java.lang.NoClassDefFoundError: org/springframework/security/core/SpringSecurityCoreVersion at org.springframework.security.config.SecurityNamespaceHandler.<init>(SecurityNamespaceHandler.java:65) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:526) at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:148) ... 69 more Caused by: java.lang.ClassNotFoundException: org.springframework.security.core.SpringSecurityCoreVersion at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1284) at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1132) ... 75 more I am using spring 3.2.7. It was not having spring security jar. So I got it downloaded using maven. It's version is 3.2.4. What is this error? There's no error in code. What must have gone wrong? For last 3 hours I have been trying to run a simple example, but totally hammered by this error. Please help

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  • How is thread synchronization implemented, at the assembly language level?

    - by Martin
    While I'm familiar with concurrent programming concepts such as mutexes and semaphores, I have never understood how they are implemented at the assembly language level. I imagine there being a set of memory "flags" saying: lock A is held by thread 1 lock B is held by thread 3 lock C is not held by any thread etc But how is access to these flags synchronized between threads? Something like this naive example would only create a race condition: mov edx, [myThreadId] wait: cmp [lock], 0 jne wait mov [lock], edx ; I wanted an exclusive lock but the above ; three instructions are not an atomic operation :(

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  • Infinispan equivalent to ehcache's copyOnRead and copyOnWrite

    - by waxwing
    Hi, I am planning to implement a cache solution into an existing web app. Nothing complicated: basically a concurrent map that supports overflowing to disk and automatic eviction. Clustering the cache could be requirement in the future, but not now. I like ehcache's copyOnRead and copyOnWrite features, because it means that I don't have to manually clone things before modifying something I take out of the cache. Now I have started to look at Infinispan, but I have not found anything equivalent there. Does it exist? I.e., the following unit tests should pass: @Test public void testCopyOnWrite() { Date date = new Date(0); cache.put(0, date); date.setTime(1000); date = cache.get(0); assertEquals(0, date.getTime()); } @Test public void testCopyOnRead() { Date date = new Date(0); cache.put(0, date); assertNotSame(cache.get(0), cache.get(0)); }

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  • ZooKeeper and RabbitMQ/Qpid together - overkill or a good combination?

    - by Chris Sears
    Greetings, I'm evaluating some components for a multi-data center distributed system. We're going to be using message queues (via either RabbitMQ or Qpid) so agents can make asynchronous requests to other agents without worrying about addressing, routing, load balancing or retransmission. In many cases, the agents will be interacting with components that were not designed for highly concurrent access, so locking and cross-agent coordination will be needed to avoid race conditions. Also, we'd like the system to automatically respond to agent or data center failures. With the above use cases in mind, ZooKeeper seemed like it might be a good fit. But I'm wondering if trying to use both ZK and message queuing is overkill. It seems like what Zookeeper does could be accomplished by my own cluster manager using AMQP messaging, but that would be hard to get really right. On the other hand, I've seen some examples where ZooKeeper was used to implement message queuing, but I think RabbitMQ/Qpid are a more natural fit for that. Has anyone out there used a combination like this? Thanks in advance, -Chris

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  • Locking NFS files in PHP

    - by Oli
    Part of my latest webapp needs to write to file a fair amount as part of its logging. One problem I've noticed is that if there are a few concurrent users, the writes can overwrite each other (instead of appending to file). I assume this is because of the destination file can be open in a number of places at the same time. flock(...) is usually superb but it doesn't appear to work on NFS... Which is a huge problem for me as the production server uses a NFS array. The closest thing I've seen to an actual solution involves trying to create a lock dir and waiting until it can be created. To say this lacks elegance is understatement of the year, possibly decade. Any better ideas? Edit: I should add that I don't have root on the server and doing the storage in another way isn't really feasible any time soon, not least within my deadline.

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  • Run java thread at specific times

    - by rmarimon
    I have a web application that synchronizes with a central database four times per hour. The process usually takes 2 minutes. I would like to run this process as a thread at X:55, X:10, X:25, and X:40 so that the users knows that at X:00, X:15, X:30, and X:45 they have a clean copy of the database. It is just about managing expectations. I have gone through the executor in java.util.concurrent but the scheduling is done with the scheduleAtFixedRate which I believe provides no guarantee about when this is actually run in terms of the hours. I could use a first delay to launch the Runnable so that the first one is close to the launch time and schedule for every 15 minutes but it seems that this would probably diverge in time. Is there an easier way to schedule the thread to run 5 minutes before every quarter hour?

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  • Web service performance testing plan, Microsoft .NET WS, SQL

    - by zxed
    Trying to answer a question to come up with a testing plan. It has to do with using a website and/or webservice that queries a sql server to get data and display to user. * Solution must be able to handle an estimated 2000 users, approximately 700 concurrent users, 10,000 + website hits a month. Database calls should handle 100,000 queries via the website/webservice a month. The system is used at multiple times during a 24 hour period; however networking and bandwidth traffic decreases after 5 pm * two windows 2003 servers are used, one for web, another for sql. Both are located in the same room. User access is varied and users can be far/near (its a centralized system), users access via www

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  • Lazy loading of child throwing session error

    - by Thomas Buckley
    I'm the following error when calling purchaseService.updatePurchase(purchase) inside my TagController: SEVERE: Servlet.service() for servlet [PurchaseAPIServer] in context with path [/PurchaseAPIServer] threw exception [Request processing failed; nested exception is org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.app.model.Purchase.tags, no session or session was closed] with root cause org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.app.model.Purchase.tags, no session or session was closed at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:383) at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:375) at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:368) at org.hibernate.collection.PersistentSet.add(PersistentSet.java:212) at com.app.model.Purchase.addTags(Purchase.java:207) at com.app.controller.TagController.createAll(TagController.java:79) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:212) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:126) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:900) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:827) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882) at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789) at javax.servlet.http.HttpServlet.service(HttpServlet.java:641) at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:309) 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) TagController: @RequestMapping(value = "purchases/{purchaseId}/tags", method = RequestMethod.POST, params = "manyTags") @ResponseStatus(HttpStatus.CREATED) public void createAll(@PathVariable("purchaseId") final Long purchaseId, @RequestBody final Tag[] entities) { Purchase purchase = purchaseService.getById(purchaseId); Set<Tag> tags = new HashSet<Tag>(Arrays.asList(entities)); purchase.addTags(tags); purchaseService.updatePurchase(purchase); } Purchase: @Entity @XmlRootElement public class Purchase implements Serializable { /** * */ private static final long serialVersionUID = 6603477834338392140L; @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; @OneToMany(mappedBy = "purchase", fetch = FetchType.LAZY, cascade={CascadeType.ALL}) private Set<Tag> tags; @JsonIgnore public Set<Tag> getTags() { if (tags == null) { tags = new LinkedHashSet<Tag>(); } return tags; } public void setTags(Set<Tag> tags) { this.tags = tags; } ... } Tag: @Entity @XmlRootElement public class Tag implements Serializable { /** * */ private static final long serialVersionUID = 5165922776051697002L; @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; @ManyToOne(fetch = FetchType.LAZY) @JoinColumns({@JoinColumn(name = "PURCHASEID", referencedColumnName = "ID")}) private Purchase purchase; @JsonIgnore public Purchase getPurchase() { return purchase; } public void setPurchase(Purchase purchase) { this.purchase = purchase; } } PurchaseService: @Service public class PurchaseService implements IPurchaseService { @Autowired private IPurchaseDAO purchaseDAO; public PurchaseService() { } @Transactional public List<Purchase> getAll() { return purchaseDAO.findAll(); } @Transactional public Purchase getById(Long id) { return purchaseDAO.findOne(id); } @Transactional public void addPurchase(Purchase purchase) { purchaseDAO.save(purchase); } @Transactional public void updatePurchase(Purchase purchase) { purchaseDAO.update(purchase); } } TagService: @Service public class TagService implements ITagService { @Autowired private ITagDAO tagDAO; public TagService() { } @Transactional public List<Tag> getAll() { return tagDAO.findAll(); } @Transactional public Tag getById(Long id) { return tagDAO.findOne(id); } @Transactional public void addTag(Tag tag) { tagDAO.save(tag); } @Transactional public void updateTag(Tag tag) { tagDAO.update(tag); } } Any ideas on how I can fix this? (I want to avoid using EAGER loading). Do I need to setup some form of session management for transactions? Thanks

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  • What is a good motivating example for dataflow concurrency?

    - by Alex Miller
    I understand the basics of dataflow programming and have encountered it a bit in Clojure APIs, talks from Jonas Boner, GPars in Groovy, etc. I know it's prevalent in languages like Io (although I have not studied Io). What I am missing is a compelling reason to care about dataflow as a paradigm when building a concurrent program. Why would I use a dataflow model instead of a mutable state+threads+locks model (common in Java, C++, etc) or an actor model (common in Erlang or Scala) or something else? In particular, while I know of library support in the languages above (and Scala and Ruby), I don't know of a single program or library that is a poster child user of this model. Who is using it? Why do they find it better than the other models I mentioned?

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  • Issue with SOAPUI: running test for concurrency

    - by Kangkan
    I am trying to test my web service using SOAPUI (the free version). For testing concurrency, I wished to fire concurrent threads from SOAPUI onto the service. But with the options, the thread count increases gradually (even in the burst mode). The machine where SOAPUI is installed is a WinXP machine. Can I actually do the concurrency testing? If so how? Please guide me. I am waiting for your answers and help.

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  • Named semaphores in Python?

    - by Boaz
    Hi, I have a script in python which uses a resource which can not be used by more than a certain amount of concurrent scripts running. Classically, this would be solved by a named semaphores but I can not find those in the documentation of the multiprocessing module or threading . Am I missing something or are named semaphores not implemented / exposed by Python? and more importantly, if the answer is no, what is the best way to emulate one? Thanks, Boaz PS. For reasons which are not so relevant to this question, I can not aggregate the task to a continuously running process/daemon or work with spawned processed - both of which, it seems, would have worked with the python API.

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  • WinUSB application or User-Mode Driver as a filter driver for USB Analysis/Sniffer/Trending

    - by Robert
    A question to maybe some who have worked extensively with WinUSB APIs or use mode USB drivers - Does anyone know if the WinUSB API or a user mode driver can be used as a passive observer of USB connections, capturing notification of interrupts, control requests, data transfers...etc without interfering with other applications (such as iTunes) which would obviously require concurrent access to the device at the same time my application is monitoring the connection and displaying data on it? Or do you pretty much have to write a kernel-mode filter driver and inject yourself in the USB stack in order to make that happen? In the past, there have been a few credible options (libusb-win32 and usbsnoop to be specific) though both are built around the old DDK, not the Windows Driver Foundation, and are not really supported on a regular basis any more. I'm hesitant to build something significant around them, as a result.

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  • Disk-based caching of dynamic images in IIS 7

    - by Daniel Schierbeck
    I'm writing an image server which needs to handle a relatively large number of concurrent requests (~5,000). The images being served are dynamically scaled down and cropped based on per-image specifications, which are queried from a database. The number of images is rather large, so an in-memory cache isn't viable (thrashing would most definitely occur). I'm using native caching in IIS 7 to avoid hitting the ASP.NET app which generates the images on-the-fly. I've looked around, but I couldn't find a simple way to configure IIS to store the cache on-disk -- is there such an option, or would I need to roll my own? I'd rather avoid placing the generated images in a public folder, so they can be served statically, since I would prefer to invalidate the cache entries using a query parameter (last-edit time from the database,) which doesn't seem possible to reconcile with static caching. I would love to get some feedback on this!

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  • Which web Tier Framework for a public commercial website with heavy load ?

    - by Maxime ARNSTAMM
    Hello everyone, As a part of an enterprise architecture exercise, i need to find a java-based framework filling these constraints : heavy (i think) load : 5000 concurrent connections widely known : can't be too exotic, the contractors would be too high priced. relatively easy to use : developpement time must be reasonnable must be as compliant as possible with the css/html layout produced by a designer Must look like "web 2.0" from the marketing point of view. What i learned from my limited experience is : jsf : 1, don't know. 2, 3 ok. 4 not ok (at least not without huge effort) wicket : 1, not really. 2, 3 and 4 ok. gwt : 1, don't know. 2, 3 ok. 4 not ok (but more ok than jsf) others : not really "web 2.0" or not really known I'm really junior, so my ideas about those frameworks are probably wrong, that's why i come to you, stackoverflowees. Thanks for helping :)

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  • dynamics CRM performance question

    - by tomo
    Hello Dynamics CRM gurus :) My boss asked me to do a research on available CMSes on market because cms we are using currently is rather a mess. For me as a .NET developer it would be great to choose and implement Dynamics CRM because of extensibility and perfect integration with .NET environment and well-known tools. All marketing blahbla sounds great but I'd like to know about common DISADVANTAGES, ISSUES concerning this system. The most important is how it is performing in a company with about 150 concurrent and very active users. I heard that is't really slow comparing to competitors system. Thanks in advance Best regards, Tomasz.

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  • In MS SQL Server, is there a way to "atomically" increment a column being used as a counter?

    - by Dan P
    Assuming a Read Committed Snapshot transaction isolation setting, is the following statement "atomic" in the sense that you won't ever "lose" a concurrent increment? update mytable set counter = counter + 1 I would assume that in the general case, where this update statement is part of a larger transaction, that it wouldn't be. For example, I think this scenario is possible: update the counter within transaction #1 do some other stuff in transaction #1 update the counter with transaction #2 commit transaction #2 commit transaction #1 In this situation, wouldn't the counter end up only being incremented by 1? Does it make a difference if that is the only statement in a transaction? How does a site like stackoverflow handle this for its question view counter? Or is the possibility of "losing" some increments just considered acceptable?

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  • C#: How to remove items from the collection of a IDictionary<E, ICollection<T>> with LINQ?

    - by Rosarch
    Here is what I am trying to do: private readonly IDictionary<float, ICollection<IGameObjectController>> layers; foreach (ICollection<IGameObjectController> layerSet in layers.Values) { foreach (IGameObjectController controller in layerSet) { if (controller.Model.DefinedInVariant) { layerSet.Remove(controller); } } } Of course, this doesn't work, because it will cause a concurrent modification exception. (Is there an equivalent of Java's safe removal operation on some iterators?) How can I do this correctly, or with LINQ?

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  • Socket server stops accepting connections after a period of time

    - by Rob
    We have an async socket server written in C#. (running on Windows Web Server 2008) It works flawlessly up until it stop accepting new connections for an unknown reason. We have about 200 concurrent connections on average, however we keep a count of both connections created and connections dropped. These figures can reach as high as 10,000 or as low as only 1000 before it just stops! It can run for up to around 8 hours sometimes before it stops or it can run for about half hour, at the moment it's running for about an hour before we have another application bring it back up automatically when that can't connect (not exactly ideal). It doesn't appear like we're running out of sockets as we're closing them properly, we're also logging all errors and nothing is happening immediately before it stops. We can figure this out. Does anyone have any ideas what might be going on? I can paste code, but it generally just the same old async beginaccept/send code you see everywhere.

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  • handling Concurrency in SQL SERVER 2005

    - by sameer
    Hi, I have one question for you, if you can answer and refer resource it will be great help. I have a scenario where i need to create a appointment slot and a serial no for each slot memberwise. ex: Member Id |App Slot # 1|1 1|2 2|1 2|2 1|3 what im doing is take the Max slot number,increamenting it and insert it memberwise. but the problem is concurrent user can create a slot when i take the max slot after that if any other user insert the slot the value that im working with is no more valid, how to over come this problem Thanks & Regards, Sameer

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