thread safe - Page 336 - Developer IT

How to implement blocking request-reply using Java concurrency primitives?

- by Uri

My system consists of a "proxy" class that receives "request" packets, marshals them and sends them over the network to a server, which unmarshals them, processes, and returns some "response packet". My "submit" method on the proxy side should block until a reply is received to the request (packets have ids for identification and referencing purposes) or until a timeout is reached. If I was building this in early versions of Java, I would likely implement in my proxy a collection of "pending messages ids", where I would submit a message, and wait() on the corresponding id (with a timeout). When a reply was received, the handling thread would notify() on the corresponding id. Is there a better way to achieve this using an existing library class, perhaps in java.util.concurrency? If I went with the solution described above, what is the correct way to deal with the potential race condition where a reply arrives before wait() is invoked?

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Perl throws an error message about syntax

- by Ben Dauphinee

So, building off a question about string matching (this thread), I am working on implementing that info in solution 3 into a working solution to the problem I am working on. However, I am getting errors, specifically about this line of the below function: next if @$args->{search_in} !~ /@$cur[1]/; syntax error at ./db_index.pl line 16, near "next " My question as a perl newbie is what am I doing wrong here? sub search_for_key { my ($args) = @_; foreach $row(@{$args->{search_ary}}){ print "@$row[0] : @$row[1]\n"; } my $thiskey = NULL; foreach $cur (@{$args->{search_ary}}){ print "\n" . @$cur[1] . "\n" next if @$args->{search_in} !~ /@$cur[1]/; $thiskey = @$cur[0]; last; } return $thiskey; }

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What mutex/locking/waiting mechanism to use when writing a Chat application with Tornado Web Framewo

- by user272973

We're implementing a Chat server using Tornado. The premise is simple, a user makes open an HTTP ajax connection to the Tornado server, and the Tornado server answers only when a new message appears in the chat-room. Whenever the connection closes, regardless if a new message came in or an error/timeout occurred, the client reopens the connection. Looking at Tornado, the question arises of what library can we use to allow us to have these calls wait on some central object that would signal them - A_NEW_MESSAGE_HAS_ARRIVED_ITS_TIME_TO_SEND_BACK_SOME_DATA. To describe this in Win32 terms, each async call would be represented as a thread that would be hanging on a WaitForSingleObject(...) on some central Mutex/Event/etc. We will be operating in a standard Python environment (Tornado), is there something built-in we can use, do we need an external library/server, is there something Tornado recommends? Thanks

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An algorithm Problem

- by Vignesh

For coverage, I've a set of run time variables of from my program execution. It happens that I get it from a series of executions(Automated testing). ie. its a vector<vector<var,value>> I've a limited set of variables with expected values and generate combination s, that is I have vector<vector<var,value>(smaller than the execution vector)>. Now I need to compare and tell which of the combination I generated were exactly executed in one of the tests. My algo is O(n^4). Is there any way to bring it down. Something like set intersection. I'm using java, and vectors because of thread safety.

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Copying a java text file into a String.

- by Deepak Konidena

Hi, I run into the following errors when i try to store a large file into a string. Exception in thread "main" java.lang.OutOfMemoryError: Java heap space at java.util.Arrays.copyOf(Arrays.java:2882) at java.lang.AbstractStringBuilder.expandCapacity(AbstractStringBuilder.java:100) at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:515) at java.lang.StringBuffer.append(StringBuffer.java:306) at rdr2str.ReaderToString.main(ReaderToString.java:52) As is evident, i am running out of heap space. Basically my pgm looks like something like this. FileReader fr = new FileReader(<filepath>); sb = new StringBuffer(); char[] b = new char[BLKSIZ]; while ((n = fr.read(b)) > 0) sb.append(b, 0, n); fileString = sb.toString(); Can someone suggest me why i am running into heap space error? Thanks.

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Best data-structure to use for two ended sorted list

- by fmark

I need a collection data-structure that can do the following: Be sorted Allow me to quickly pop values off the front and back of the list Remain sorted after I insert a new value Allow a user-specified comparison function, as I will be storing tuples and want to sort on a particular value Thread-safety is not required Optionally allow efficient haskey() lookups (I'm happy to maintain a separate hash-table for this though) My thoughts at this stage are that I need a priority queue and a hash table, although I don't know if I can quickly pop values off both ends of a priority queue. I'm interested in performance for a moderate number of items (I would estimate less than 200,000). Another possibility is simply maintaining an OrderedDictionary and doing an insertion sort it every-time I add more data to it. Furthermore, are there any particular implementations in Python. I would really like to avoid writing this code myself.

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Unknown error in Producer/Consumer program, believe it to be an infinite loop.

- by ray2k

Hello, I am writing a program that is solving the producer/consumer problem, specifically the bounded-buffer version(i believe they mean the same thing). The producer will be generating x number of random numbers, where x is a command line parameter to my program. At the current moment, I believe my program is entering an infinite loop, but I'm not sure why it is occurring. I believe I am executing the semaphores correctly. You compile it like this: gcc -o prodcon prodcon.cpp -lpthread -lrt Then to run, ./prodcon 100(the number of randum nums to produce) This is my code. typedef int buffer_item; #include <stdlib.h> #include <stdio.h> #include <pthread.h> #include <semaphore.h> #include <unistd.h> #define BUFF_SIZE 10 #define RAND_DIVISOR 100000000 #define TRUE 1 //two threads void *Producer(void *param); void *Consumer(void *param); int insert_item(buffer_item item); int remove_item(buffer_item *item); int returnRandom(); //the global semaphores sem_t empty, full, mutex; //the buffer buffer_item buf[BUFF_SIZE]; //buffer counter int counter; //number of random numbers to produce int numRand; int main(int argc, char** argv) { /* thread ids and attributes */ pthread_t pid, cid; pthread_attr_t attr; pthread_attr_init(&attr); pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM); numRand = atoi(argv[1]); sem_init(&empty,0,BUFF_SIZE); sem_init(&full,0,0); sem_init(&mutex,0,0); printf("main started\n"); pthread_create(&pid, &attr, Producer, NULL); pthread_create(&cid, &attr, Consumer, NULL); printf("main gets here"); pthread_join(pid, NULL); pthread_join(cid, NULL); printf("main done\n"); return 0; } //generates a randum number between 1 and 100 int returnRandom() { int num; srand(time(NULL)); num = rand() % 100 + 1; return num; } //begin producing items void *Producer(void *param) { buffer_item item; int i; for(i = 0; i < numRand; i++) { //sleep for a random period of time int rNum = rand() / RAND_DIVISOR; sleep(rNum); //generate a random number item = returnRandom(); //acquire the empty lock sem_wait(&empty); //acquire the mutex lock sem_wait(&mutex); if(insert_item(item)) { fprintf(stderr, " Producer report error condition\n"); } else { printf("producer produced %d\n", item); } /* release the mutex lock */ sem_post(&mutex); /* signal full */ sem_post(&full); } return NULL; } /* Consumer Thread */ void *Consumer(void *param) { buffer_item item; int i; for(i = 0; i < numRand; i++) { /* sleep for a random period of time */ int rNum = rand() / RAND_DIVISOR; sleep(rNum); /* aquire the full lock */ sem_wait(&full); /* aquire the mutex lock */ sem_wait(&mutex); if(remove_item(&item)) { fprintf(stderr, "Consumer report error condition\n"); } else { printf("consumer consumed %d\n", item); } /* release the mutex lock */ sem_post(&mutex); /* signal empty */ sem_post(&empty); } return NULL; } /* Add an item to the buffer */ int insert_item(buffer_item item) { /* When the buffer is not full add the item and increment the counter*/ if(counter < BUFF_SIZE) { buf[counter] = item; counter++; return 0; } else { /* Error the buffer is full */ return -1; } } /* Remove an item from the buffer */ int remove_item(buffer_item *item) { /* When the buffer is not empty remove the item and decrement the counter */ if(counter > 0) { *item = buf[(counter-1)]; counter--; return 0; } else { /* Error buffer empty */ return -1; } }

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Refresh layout while filling it

- by neutrino

Hi guys, I have an activity with a HorizontalScrollView. When it opens, I start filling this view (or rather, a container layout inside it) with another views. This is done from another thread by using handler.post. The views are added in bunches of 15, and when there are no more views to add, I start updating them with new data (this is a kind of streaming data from a server). The problem is that the scrollview is empty until all of the views are added. As soon as they are all added and start updating, the scrollview gets drawn. How do I refresh it in the process of adding views? I don't want the screen to be empty for 3 seconds while all of the views are added. Thanks a lot. UPDATE: turned out this problem is not specific for HorizontalScrollView, this is the case for any generic layout.

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In WPF using a ListView is there an elegant way to auto resize items?

- by Justin

I recently wrote, my first, WPF application that has a list of items that are polled from a web-serivce. The items are displayed/data-bound in a ListView via a GridView. A background thread periodically polls the web-serivce and updates the list. If, say, I had three items initially bound to the ListView that simply display a description and the three descriptions where something like: - ProjectA - ProjectB - ProjectC Later a new item is added with a description of 'AReallyReallyLongProjectName', I would end up with a list like: - ProjectA - ProjectB - ProjectC - AReallyR The GridViewColumn would not update it's width and would subsequently cut off any new items that extended the original width. I added this bit of code which forces the column to resize, but it just seems a little hacky. (Just seems weird to set a width just to set it back to nothing to force the resize) if(gridView != null) { foreach(var column in gridView.Columns) { if (double.IsNaN(column.Width) column.Width = column.ActualWidth; column.Width = double.NaN; } } Is there a better, more elegant solution, to accomplish this same thing?

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Can I mix compile time string comparison with MPL templates?

- by Negative Zero

I got this compile time string comparison from another thread using constexpr and C++11 (http://stackoverflow.com/questions/5721813/compile-time-assert-for-string-equality). It works with constant strings like "OK" constexpr bool isequal(char const *one, char const *two) { return (*one && *two) ? (*one == *two && isequal(one + 1, two + 1)) : (!*one && !*two); } I am trying to use it in the following context: static_assert(isequal(boost::mpl::c_str<boost::mpl::string<'ak'>>::value, "ak"), "should not fail"); But it gives me an compilation error of static_assert expression is not an constant integral expression. Can I do this?

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Service injection into Controller (Spring MVC)

- by ThaSaleni

Hi I have a Spring web application, I have built it up to the controller stage and I could inject my Daos, into my Services fine. Now when I want to inject my Service into my controller i get an error for dependency with the Dao and further down the sessionFactory. I don't want to inject these again cause this will ultimately lead me to eventually create a data source but I have my Daos for data access and they already know about sessionFactory. Am I missing something here? here's the sample code snippets My Service: @Service("productService") @Transactional public class ProductServiceImpl implements ProductService { private ProductDao productDao; @Autowired public void setDao(ProductDao productDao) { this.productDao = productDao; } My Controller @Controller @WebServlet(name="controllerServlet", loadOnStartup= urlPatterns=...}) public class ControllerServlet extends HttpServlet { boolean isUserLogedIn =false; @Autowired private ProductService productService; public void setProductService(ProductService productService){ this.productService = productService; } Servlet-context Stack trace javax.servlet.ServletException: Servlet.init() for servlet mvcServlet threw exception org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98) org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999) org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java: 565) org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1812) java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) java.lang.Thread.run(Thread.java:662) root cause org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'controllerServlet': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.phumzile.acme.services.ProductService com.phumzile.acme.client.web.controller.ControllerServlet.productService; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.phumzile.acme.services.ProductService] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)} org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.p ostProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:287) org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1106) org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517) org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456) org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294) org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225) SERVLET-CONTEXT <context:component-scan base-package="com.phumzile.acme.client" />  <mvc:annotation-driven /> </beans> APP-CONFIG <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> <property name="locations"> <list> <value>configuration.properties</value> </list> </property> </bean> <context:annotation-config/> <context:component-scan base-package="com.phumzile.acme" /> <import resource="db-config.xml" /> </beans> DB-CONFIG <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close"> <property name="idleConnectionTestPeriod" value="10800"/> <property name="maxIdleTime" value="21600"/> <property name="driverClass"> <value>${jdbc.driver.className}</value> </property> <property name="jdbcUrl"> <value>${jdbc.url}</value> </property> <property name="user"> <value>${jdbc.username}</value> </property> <property name="password"> <value>${jdbc.password}</value> </property> </bean> <bean id="sessionFactory" class="org.springframework.orm.hibernate3.a nnotation.AnnotationSessionFactoryBean"> <property name="dataSource"> <ref bean="dataSource" /> </property> <property name="annotatedClasses"> <list>  <value>com.phumzile.acme.model.User</value> <value>com.phumzile.acme.model.Person</value> <value>com.phumzile.acme.model.Company</value> <value>com.phumzile.acme.model.Product</value> <value>com.phumzile.acme.model.Game</value> <value>com.phumzile.acme.model.Book</value>  </list> </property> <property name="packagesToScan" value="com.phumzile.acme" /> <property name="hibernateProperties"> <props> <prop key="hibernate.dialect">${jdbc.hibernate.dialect </prop> <prop key="hibernate.hbm2ddl.auto">validate</prop> <prop key="hibernate.show_sql">true</prop> </props> </property> </bean> <bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager"> <property name="sessionFactory"> <ref bean="sessionFactory" /> </property> </bean> <tx:annotation-driven /> </beans> CONFIGURATION.PROPERTIES jdbc.driver.className=com.mysql.jdbc.Driver jdbc.url=jdbc:mysql://localhost:3306/mydb jdbc.username=root jdbc.password=root jdbc.hibernate.dialect=org.hibernate.dialect.MySQLDialect

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C# Socket Server

- by Snoopy

In .NET 3.5 a new socket classes was released: http://msdn.microsoft.com/en-us/library/bb968780.aspx i found a sample but some questions regarding best practicses are remaining: http://code.msdn.microsoft.com/nclsamples/Wiki/View.aspx?title=Socket%20Performance m_numConnections (the maximum number of connections the sample is designed to handle simultaneously) is probably equal to the amount of cpu cores i have. m_receiveBufferSize is the size for one packet? like 8kb? how should i handle a length byte? opsToPreAlloc i dont understand. is this if i code a transparent proxy? Regarding the multithreading, what should be used? The reactive extension seem to be a good choice. Has anyone tried this in a real world project? Are there better options? I had bad experiences with the .NET thread pool in the past.

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Killing COM object from C#

- by Pradeep

I have a COM object that we are calling from C#. This works great, and I have my own pool of objects that I can use whenever I want. Now I need to kill the object. I've tried releasing the COM object explicitly and then garbage collecting from another thread, but that does nothing. Does anyone have any other ideas to kill this object? Thanks for the help. I've tried System.Runtime.InteropServices.Marshal.ReleaseComObject(myApp); GC.Collect(); GC.WaitForPendingFinalizers (); myApp = null; and I create it by myApplication.ApplicationClass myApp = new myApplication.ApplicationClass(); Thanks, Pradeep

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memory usage in C# (.NET) app is very high, until I call System.GC.Collect()

- by Chris Gray

I've written an app that spins a few threads each of which read several MB of memory. Each thread then connects to the Internet and uploads the data. this occurs thousands of times and each upload takes some time I'm seeing a situation where (verified with windbg/sos and !dumpheap) that the Byte[] are not getting collected automatically, causing 100/150MB of memory to be reported in task manager if I call System.GC.Collect() i'm seeing a huge drop in memory, a drop of over 100MB I dont like calling System.GC.Collect() and my PC has tons of free memory. however if anyone looks at TaskManager they're going to be concerned, thinking my app is leaking horribly. tips?

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NSOpenGLView in NSSplitView

- by Remizorrr

When i put an NSOpenglView in NSSplitView, a problem occurs while dragging splitter. The openGLView and SplitView are resizing asynchronously. i found a solution in apple mail list thread http://developer.apple.com/mac/library/samplecode/GLChildWindowDemo/Introduction/Intro.html and i found a solution with some carbon calls. but now i get link error (only in release mode). so i'v got two questions - is there any cocoa way to fix the splitter - gl problem? if no - how can i fix carbon linker errors in release mode?

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What is the scope of require_once in PHP?

- by TMG

Simple question: Is the scope of require_once global? For example: <?PHP require_once('baz.php'); // do some stuff foo ($bar); function foo($bar) { require_once('baz.php'); // do different stuff } ?> When foo is called, does it re-parse baz.php? Or does it rely on the already required file from the main php file (analagous to calling require_once twice consecutively for the same include file)? I saw this thread before, but it didn't quite answer the question: http://stackoverflow.com/questions/1669707/should-require-once-some-file-php-appear-anywhere-but-the-top-of-the-file Thanks for your help!

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getting core file

- by ashwani66476

Hello All I am running a Core JAVA application on AIX machine, and it creates a file named "core". My concern are 1. I am not able to open this "core" file in "Heap Analyzer" or "Thread Analyzer". 2. Which tools do I need to use, So that I can analyze this "core" file. 3. Could any one elaborate more about this file? why this "core" file creates. Waiting for response..... Many Thanks

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null pointer exception at org.hibernate.tuple.AbstractEntityTuplizer.createProxy

- by saurabh

I am using hibernate 3.2 with struts 1.2 framework I got this exception when i m trying to load the object I am using this code to load the object public Currentprofile findById(java.lang.String id) { log.debug("getting Currentprofile instance with id: " + id); try { Currentprofile instance = (Currentprofile) getSession().get( "com.hibermappings.Currentprofile", id); return instance; } catch (RuntimeException re) { log.error("get failed", re); throw re; } } my hbm file is this <one-to-one name="referenceDb" lazy="proxy" class="com.hibermappings.ReferenceDb" cascade="all" constrained="false" /> <one-to-one name="registration" lazy="proxy" class="com.hibermappings.Registration" cascade="all" constrained="false" /> <one-to-one name="jobseekerpackagedetails" lazy="proxy" class="com.hibermappings.Jobseekerpackagedetails" cascade="all" constrained="false" /> <property name="keyWords" type="java.lang.String"> <column name="keyWords" length="5000" /> </property> <property name="totalExp" type="java.lang.String"> <column name="totalExp" length="100" /> </property> <property name="hqualification" type="java.lang.String"> <column name="hQualification" length="100" /> </property> <property name="preferedLocation" type="java.lang.String"> <column name="preferedLocation" length="100" /> </property> <property name="functionalArea" type="java.lang.String"> <column name="functionalArea" length="1000" /> </property> <property name="expSalary" type="java.lang.String"> <column name="expSalary" length="100" /> </property> <property name="designation" type="java.lang.String"> <column name="designation" length="100" /> </property> <property name="resumeTitle" type="java.lang.String"> <column name="resumeTitle" length="500" /> </property> <property name="profileDetails" type="java.lang.String"> <column name="profileDetails" length="65535" /> </property> <property name="requiredProfile" type="java.lang.String"> <column name="requiredProfile" length="65535" /> </property> <property name="activatedOn" type="java.util.Date"> <column name="activatedOn" length="0" /> </property> <set name="resumes" inverse="true" cascade="save-update"> <key> <column name="jobseekerId" length="50" /> </key> <one-to-many class="com.hibermappings.Resume" /> </set> </class> the same code runs well when I m using in a simple java class within main method .. full stack trace of exception is java.lang.NullPointerException at org.hibernate.tuple.AbstractEntityTuplizer.createProxy(AbstractEntityTuplizer.java:372) at org.hibernate.persister.entity.AbstractEntityPersister.createProxy(AbstractEntityPersister.java:3121) at org.hibernate.event.def.DefaultLoadEventListener.createProxyIfNecessary(DefaultLoadEventListener.java:232) at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:173) at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:87) at org.hibernate.impl.SessionImpl.fireLoad(SessionImpl.java:862) at org.hibernate.impl.SessionImpl.load(SessionImpl.java:781) at org.hibernate.impl.SessionImpl.load(SessionImpl.java:774) at com.DAOs.CurrentprofileDAO.getLoad(CurrentprofileDAO.java:71) at com.action.JobSekeerManage.viewProfile(JobSekeerManage.java:447) 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:585) at org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:270) at org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:187) at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431) at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236) at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196) at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414) at javax.servlet.http.HttpServlet.service(HttpServlet.java:689) at javax.servlet.http.HttpServlet.service(HttpServlet.java:802) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:237) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157) at com.filter.HibernateFilter.doFilter(HibernateFilter.java:24) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:186) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:214) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:825) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:731) at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:526) at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80) at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684) at java.lang.Thread.run(Thread.java:595) Error::null

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producing a typewriter-like effect

- by Tony Ennis

Android newb here. Please use small words :-) I'd like to simulate typewriter output on my Android. The output being displayed is generated by a game and is somewhat freeform. The effect I want to see individual characters appear at a rate of about 6 characters a second. When a 'carriage return' is seen, I'd like to insert a delay then resume typing on the left. What are some suggestions on views? Would the view of choice for this be a TextView? Even that seems like overkill for this read-only coarsely scrolling output. I saw something on this thread about an AsyncTask. That looks useful. Perhaps my game will write to some manner of buffer, and a subclass of AsyncTask will pull characters out every .15 seconds or so, add them to the TextView, then invalidate() the TextView? Sound like a plan?

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PHP fastest method of reading server response

- by Peter John

Hi there, im having some real problems with the lag produced by using fgets to grab the server's response to some batch database calls im making. Im sending through a batch of say, 10,000 calls and ive tracked the lag down to fgets causing the hold up in the speed of my application as the response for each call needs to be grabbed. I have found this thread http://bugs.php.net/bug.php?id=32806 which explains the problem quite well, but hes reading a file, not a server response so fread could be a bit tricky as i could get part of the next line, and extra stuff which i dont want. Any help much appreciated!

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Django Comments and Users integration

- by Patrick

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dynamically change bitmap in imageView, android

- by Junfei Wang

All, I have a problem related to imageView, android. I have array which contains of 10 bitmap objects, called bm. I have a imageView, called im. Now I wanna show the bitmaps in the array in im one by one, so I did the following: new Thread(new Runnable() { public void run() { for(int j=0;j<10;j++){ im.setImageBitmap(bm[j]); } } }).start(); But the result only shows the last bitmap in the array. Can someone tell me what to do with this issue? Millions of thanks!

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SetWindowHookEx and execution blocking

- by Kalaz

Hello, I just wonder... I mainly use .NET but now I started to investigate WINAPI calls. For example I am using this piece of code to hook to the API functions. It starts freezing, when I try to debug the application... using System; using System.Diagnostics; using System.Runtime.InteropServices; using System.Threading; using System.Windows.Forms; public class Keyboard { private const int WH_KEYBOARD_LL = 13; private const int WM_KEYDOWN = 0x0100; private static LowLevelKeyboardProc _proc = HookCallback; private static IntPtr _hookID = IntPtr.Zero; public static event Action<Keys,bool, bool> KeyDown; public static void Hook() { new Thread(new ThreadStart(()=> { _hookID = SetHook(_proc); Application.Run(); })).Start(); } public static void Unhook() { UnhookWindowsHookEx(_hookID); } private static IntPtr SetHook(LowLevelKeyboardProc proc) { using (Process curProcess = Process.GetCurrentProcess()) using (ProcessModule curModule = curProcess.MainModule) { return SetWindowsHookEx(WH_KEYBOARD_LL, proc, GetModuleHandle(curModule.ModuleName), 0); } } private delegate IntPtr LowLevelKeyboardProc( int nCode, IntPtr wParam, IntPtr lParam); private static IntPtr HookCallback( int nCode, IntPtr wParam, IntPtr lParam) { if (nCode >= 0 && wParam == (IntPtr)WM_KEYDOWN) { int vkCode = Marshal.ReadInt32(lParam); Keys k = (Keys) vkCode; if (KeyDown != null) { KeyDown.BeginInvoke(k, IsKeyPressed(VirtualKeyStates.VK_CONTROL), IsKeyPressed(VirtualKeyStates.VK_SHIFT),null,null); } } return CallNextHookEx(_hookID, nCode, wParam, lParam); } private static bool IsKeyPressed(VirtualKeyStates virtualKeyStates) { return (GetKeyState(virtualKeyStates) & (1 << 7))==128; } [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)] private static extern IntPtr SetWindowsHookEx(int idHook, LowLevelKeyboardProc lpfn, IntPtr hMod, uint dwThreadId); [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)] [return: MarshalAs(UnmanagedType.Bool)] private static extern bool UnhookWindowsHookEx(IntPtr hhk); [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)] private static extern IntPtr CallNextHookEx(IntPtr hhk, int nCode, IntPtr wParam, IntPtr lParam); [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)] private static extern IntPtr GetModuleHandle(string lpModuleName); [DllImport("user32.dll")] static extern short GetKeyState(VirtualKeyStates nVirtKey); } enum VirtualKeyStates : int { VK_LBUTTON = 0x01, VK_RBUTTON = 0x02, VK_CANCEL = 0x03, VK_MBUTTON = 0x04, // VK_XBUTTON1 = 0x05, VK_XBUTTON2 = 0x06, // VK_BACK = 0x08, VK_TAB = 0x09, // VK_CLEAR = 0x0C, VK_RETURN = 0x0D, // VK_SHIFT = 0x10, VK_CONTROL = 0x11, VK_MENU = 0x12, VK_PAUSE = 0x13, VK_CAPITAL = 0x14, // VK_KANA = 0x15, VK_HANGEUL = 0x15, /* old name - should be here for compatibility */ VK_HANGUL = 0x15, VK_JUNJA = 0x17, VK_FINAL = 0x18, VK_HANJA = 0x19, VK_KANJI = 0x19, // VK_ESCAPE = 0x1B, // VK_CONVERT = 0x1C, VK_NONCONVERT = 0x1D, VK_ACCEPT = 0x1E, VK_MODECHANGE = 0x1F, // VK_SPACE = 0x20, VK_PRIOR = 0x21, VK_NEXT = 0x22, VK_END = 0x23, VK_HOME = 0x24, VK_LEFT = 0x25, VK_UP = 0x26, VK_RIGHT = 0x27, VK_DOWN = 0x28, VK_SELECT = 0x29, VK_PRINT = 0x2A, VK_EXECUTE = 0x2B, VK_SNAPSHOT = 0x2C, VK_INSERT = 0x2D, VK_DELETE = 0x2E, VK_HELP = 0x2F, // VK_LWIN = 0x5B, VK_RWIN = 0x5C, VK_APPS = 0x5D, // VK_SLEEP = 0x5F, // VK_NUMPAD0 = 0x60, VK_NUMPAD1 = 0x61, VK_NUMPAD2 = 0x62, VK_NUMPAD3 = 0x63, VK_NUMPAD4 = 0x64, VK_NUMPAD5 = 0x65, VK_NUMPAD6 = 0x66, VK_NUMPAD7 = 0x67, VK_NUMPAD8 = 0x68, VK_NUMPAD9 = 0x69, VK_MULTIPLY = 0x6A, VK_ADD = 0x6B, VK_SEPARATOR = 0x6C, VK_SUBTRACT = 0x6D, VK_DECIMAL = 0x6E, VK_DIVIDE = 0x6F, VK_F1 = 0x70, VK_F2 = 0x71, VK_F3 = 0x72, VK_F4 = 0x73, VK_F5 = 0x74, VK_F6 = 0x75, VK_F7 = 0x76, VK_F8 = 0x77, VK_F9 = 0x78, VK_F10 = 0x79, VK_F11 = 0x7A, VK_F12 = 0x7B, VK_F13 = 0x7C, VK_F14 = 0x7D, VK_F15 = 0x7E, VK_F16 = 0x7F, VK_F17 = 0x80, VK_F18 = 0x81, VK_F19 = 0x82, VK_F20 = 0x83, VK_F21 = 0x84, VK_F22 = 0x85, VK_F23 = 0x86, VK_F24 = 0x87, // VK_NUMLOCK = 0x90, VK_SCROLL = 0x91, // VK_OEM_NEC_EQUAL = 0x92, // '=' key on numpad // VK_OEM_FJ_JISHO = 0x92, // 'Dictionary' key VK_OEM_FJ_MASSHOU = 0x93, // 'Unregister word' key VK_OEM_FJ_TOUROKU = 0x94, // 'Register word' key VK_OEM_FJ_LOYA = 0x95, // 'Left OYAYUBI' key VK_OEM_FJ_ROYA = 0x96, // 'Right OYAYUBI' key // VK_LSHIFT = 0xA0, VK_RSHIFT = 0xA1, VK_LCONTROL = 0xA2, VK_RCONTROL = 0xA3, VK_LMENU = 0xA4, VK_RMENU = 0xA5, // VK_BROWSER_BACK = 0xA6, VK_BROWSER_FORWARD = 0xA7, VK_BROWSER_REFRESH = 0xA8, VK_BROWSER_STOP = 0xA9, VK_BROWSER_SEARCH = 0xAA, VK_BROWSER_FAVORITES = 0xAB, VK_BROWSER_HOME = 0xAC, // VK_VOLUME_MUTE = 0xAD, VK_VOLUME_DOWN = 0xAE, VK_VOLUME_UP = 0xAF, VK_MEDIA_NEXT_TRACK = 0xB0, VK_MEDIA_PREV_TRACK = 0xB1, VK_MEDIA_STOP = 0xB2, VK_MEDIA_PLAY_PAUSE = 0xB3, VK_LAUNCH_MAIL = 0xB4, VK_LAUNCH_MEDIA_SELECT = 0xB5, VK_LAUNCH_APP1 = 0xB6, VK_LAUNCH_APP2 = 0xB7, // VK_OEM_1 = 0xBA, // ';:' for US VK_OEM_PLUS = 0xBB, // '+' any country VK_OEM_COMMA = 0xBC, // ',' any country VK_OEM_MINUS = 0xBD, // '-' any country VK_OEM_PERIOD = 0xBE, // '.' any country VK_OEM_2 = 0xBF, // '/?' for US VK_OEM_3 = 0xC0, // '`~' for US // VK_OEM_4 = 0xDB, // '[{' for US VK_OEM_5 = 0xDC, // '\|' for US VK_OEM_6 = 0xDD, // ']}' for US VK_OEM_7 = 0xDE, // ''"' for US VK_OEM_8 = 0xDF, // VK_OEM_AX = 0xE1, // 'AX' key on Japanese AX kbd VK_OEM_102 = 0xE2, // "<>" or "\|" on RT 102-key kbd. VK_ICO_HELP = 0xE3, // Help key on ICO VK_ICO_00 = 0xE4, // 00 key on ICO // VK_PROCESSKEY = 0xE5, // VK_ICO_CLEAR = 0xE6, // VK_PACKET = 0xE7, // VK_OEM_RESET = 0xE9, VK_OEM_JUMP = 0xEA, VK_OEM_PA1 = 0xEB, VK_OEM_PA2 = 0xEC, VK_OEM_PA3 = 0xED, VK_OEM_WSCTRL = 0xEE, VK_OEM_CUSEL = 0xEF, VK_OEM_ATTN = 0xF0, VK_OEM_FINISH = 0xF1, VK_OEM_COPY = 0xF2, VK_OEM_AUTO = 0xF3, VK_OEM_ENLW = 0xF4, VK_OEM_BACKTAB = 0xF5, // VK_ATTN = 0xF6, VK_CRSEL = 0xF7, VK_EXSEL = 0xF8, VK_EREOF = 0xF9, VK_PLAY = 0xFA, VK_ZOOM = 0xFB, VK_NONAME = 0xFC, VK_PA1 = 0xFD, VK_OEM_CLEAR = 0xFE } It works well even if you put messagebox into the event or something that blocks execution. But it gets bad if you try to put breakpoint into the event. Why? I mean event is not run in the same thread that the windows hook is. That means that It shouldn't block HookCallback. It does however... I would really like to know why is this happening. My theory is that Visual Studio when breaking execution temporarily stops all threads and that means that HookCallback is blocked... Is there any book or valuable resource that would explain concepts behind all of this threading?

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JavaScript on Android randomly stops working

- by AndersWid

Hi! I have an application that uses a WebView and a html-page with javascript functions. Randomly the JavaScript functions doesn't seem to be called. It works up to a random point (I have looked at this bug all day) can only be produced on hardware (HTC Legend) not on emulator. Basicly I'm using callback to javaScript whenever the user presses a button, these callbacks tell the html to redraw using javaScript functions. mHandler.post(new Runnable() { public void run() { mWebView.loadUrl("javascript:getDataLine()"); } }); The first line in this javaScript code is an alert that says that it has started, so that I can see that it's working. Settings alerts or console.log's everywhere won't help as it seems the problem is in the webview or in Android itself. I need a way to see what's going on in the background. Maybe see if a previous call failed and stalled the thread or something.

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Vista stuck at "Shutting down..." screen. Any way to get verbose logging?

- by CapBBeard

Hi all, My home machine has been running fine for about 3 years, no problems at all. Within the last couple of weeks it's had real trouble trying to shut down. It'll get so far and then just sit there at the "Shutting down..." screen for hours. I've left it overnight, I've tried in safe mode, all to no avail. These days, I just wait for the disk activity to finish up and then hold the power button to turn it off. Feels dirty as, especially because there's a RAID involved! The hardware itself is in pretty good shape and of decent spec; Core 2 Quad, 4GB RAM, 1TB RAID 1+0, so it's not quite like a 7 year old PC coming to end of life! In the last month, hardware hasn't changed except for a new monitor. Admittedly I haven't tried unplugging the monitor but I've never heard of that preventing a shutdown. I might give it a whirl later I guess, as a last resort. I've uninstalled old apps, done updates, checked the event log, looked in device manager, uninstalled all non-present devices, disabled various non-critical devices (imaging, audio etc), unplugged peripherals, stopped non-essential services, unplugged the network, disabled the network adapter entirely, ran chkdsk, verified my RAID, the list goes on. But not a single lead. I'm pretty stumped. It could be hardware, but I have no other evidence to suggest so; when the PC is running, it runs fine. Temperatures are good, gaming is smooth as always, disk performance is fine. Event log even makes it look like the shutdown was completed (gets to the point where the event log service stops). In fact, the PC doesn't appear to realise that I cut the power to it. So my question is, does anyone know if there is a way I can get some verbose output (or a log) from shutdown to give me some idea of what is causing the issue? I'm guessing it's stuck unloading some app/driver but it would be good to get some specifics! Unless anyone has any other ideas? I suspect a reinstall would resolve the issue, however I'm looking to get a new PC built in the next month or so, and the reinstall is going to be quite a big job so I'd rather just wait until then if it comes to that. Would still be nice to get this sorted in the mean time though. Cheers!

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