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• App hosting Report Viewer crashes on exit after export

  - by Paul Sasik

  We have a .NET Winforms application that hosts the Crystal Reports Viewer control (Version XI). It works well for the most part but when an export of data from the viewer is performed the application will crash on exit and in unmanaged code. The error message is not very useful and just says that an incorrect memory location was accessed. No other info such a specific DLL etc. is provided. This only happens after the viewer is used to export a report to CSV, XML etc. My guess is that at some point in the export process Crystal creates a resource that attempts an action on shut down to a parent window (perhaps) that no longer exists. I've seen a number of memory leak and shut down issues with Crystal but this one's new. Has anyone seen it and come up with a workaround or has ideas for workarounds? So far we've tried explicitly disposing of all crystal-related objects, setting to null and even setting a Thread.Sleep cycle on shut down to "give Crystal time to clean up." Update: The crash happens only on shut down (so not immediate) All export formats work All export files are created properly CR is installed on the same machine as the hosting .NET app not sure about exporting from the IDE... is that even possible?

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• What are Code Smells? What is the best way to correct them?

  - by Rob Cooper

  OK, so I know what a code smell is, and the Wikipedia Article is pretty clear in its definition: In computer programming, code smell is any symptom in the source code of a computer program that indicates something may be wrong. It generally indicates that the code should be refactored or the overall design should be reexamined. The term appears to have been coined by Kent Beck on WardsWiki. Usage of the term increased after it was featured in Refactoring. Improving the Design of Existing Code. I know it also provides a list of common code smells. But I thought it would be great if we could get clear list of not only what code smells there are, but also how to correct them. Some Rules Now, this is going to be a little subjective in that there are differences to languages, programming style etc. So lets lay down some ground rules: ** ONE SMELL PER ANSWER PLEASE! & ADVISE ON HOW TO CORRECT! ** See this answer for a good display of what this thread should be! DO NOT downmod if a smell doesn't apply to your language or development methodology We are all different. DO NOT just quickly smash in as many as you can think of Think about the smells you want to list and get a good idea down on how to work around. DO downmod answers that just look rushed For example "dupe code - remove dupe code". Let's makes it useful (e.g. Duplicate Code - Refactor into separate methods or even classes, use these links for help on these common.. etc. etc.). DO upmod answers that you would add yourself If you wish to expand, then answer with your thoughts linking to the original answer (if it's detailed) or comment if its a minor point. DO format your answers! Help others to be able to read it, use code snippets, headings and markup to make key points stand out!

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• How can this code throw a NullReferenceException?

  - by Davy8

  I must be going out of my mind, because my unit tests are failing because the following code is throwing a null ref exception: int pid = 0; if (parentCategory != null) { Console.WriteLine(parentCategory.Id); pid = parentCategory.Id; } The line that's throwing it is: pid = parentCategory.Id; The console.writeline is just to debug in the NUnit GUI, but that outputs a valid int. Edit: It's single-threaded so it can't be assigned to null from some other thread, and the fact the the Console.WriteLine successfully prints out the value shows that it shouldn't throw. Edit: Relevant snippets of the Category class: public class Category { private readonly int id; public Category(Category parent, int id) { Parent = parent; parent.PerformIfNotNull(() => parent.subcategories.AddIfNew(this)); Name = string.Empty; this.id = id; } public int Id { get { return id; } } } Well if anyone wants to look at the full code, it's on Google Code at http://code.google.com/p/chefbook/source/checkout I think I'm going to try rebooting the computer... I've seen pretty weird things fixed by a reboot. Will update after reboot. Update: Mystery solved. Looks like NUnit shows the error line as the last successfully executed statement... Copy/pasted test into new console app and ran in VS showed that it was the line after the if statement block (not shown) that contained a null ref. Thanks for all the ideas everyone. +1 to everyone that answered.

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• Inject runtime exception to pthread sometime fails. How to fix that?

  - by lionbest

  I try to inject the exception to thread using signals, but some times the exception is not get caught. For example the following code: void _sigthrow(int sig) { throw runtime_error(strsignal(sig)); } struct sigaction sigthrow = {{&_sigthrow}}; void* thread1(void*) { sigaction(SIGINT,&sigthrow,NULL); try { while(1) usleep(1); } catch(exception &e) { cerr << "Thread1 catched " << e.what() << endl; } }; void* thread2(void*) { sigaction(SIGINT,&sigthrow,NULL); try { while(1); } catch(exception &e) { cerr << "Thread2 catched " << e.what() << endl; //never goes here } }; If I try to execute like: int main() { pthread_t p1,p2; pthread_create( &p1, NULL, &thread1, NULL ); pthread_create( &p2, NULL, &thread2, NULL ); sleep(1); pthread_kill( p1, SIGINT); pthread_kill( p2, SIGINT); sleep(1); return EXIT_SUCCESS; } I get the following output: Thread1 catched Interrupt terminate called after throwing an instance of 'std::runtime_error' what(): Interrupt Aborted How can I make second threat catch exception? Is there better idea about injecting exceptions?

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• How should developers cope with so many GUI configuration combinations?

  - by shawn-harrison

  These days, any decent Windows desktop application must perform well and look good under the following conditions: XP and Vista and Windows 7. 32 bit and 64 bit. With and without Themes. With and without Aero. At 96 and 120 and perhaps custom DPIs. One or more monitors (screens). Each OS has its own preferred font. Oh my! What is a lowly little Windows desktop application developer to do? :( I'm hoping to get a thread started with suggestions on how to deal with this GUI dilemma. First off, I'm on Delphi 7. a) Does Delphi 2010 bring anything new to the table to help with this situation? b) Should we pick an aftermarket component suite and rely on them to solve all these problems? c) Should we go with an aftermarket skinning engine? d) Perhaps a more HTML-type GUI is the way to go. Can we make a relatively complex GUI app with HTML that doesn't require using a browser? (prefer to keep it form based) e) Should we just knuckle down and code through each one of these scenarios and quit bitching about it? f) And finally, how in the world are we supposed to test all these conditions?

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• Question about how to implement a c# host application with a plugin-like architecture

  - by devoured elysium

  I want to have an application that works as a Host to many other small applications. Each one of those applications should work as kind of plugin to this main application. I call them plugins not in the sense they add something to the main application, but because they can only work with this Host application as they depend on some of its services. My idea was to have each of those plugins run in a different app domain. The problem seems to be that my host application should have a set of services that my plugins will want to use and from what is my understanding making data flow in and out from different app domains is not that great of a thing. On one hand I'd like them to behave as stand-alone applications(although, as I said, they need to use lots of times the host application services), but on the other hand I'd like that if any of them crashes, my main application wouldn't suffer from it. What is the best (.NET) approach to this kind of situation? Make them all run on the same AppDomain but each one in a different Thread? Use different AppDomains? One for each "plugin"? How would I make them communicate with the Host Application? Any other way of doing this? Although speed is not an issue here, I wouldn't like for function calls to be that much slower than they are when we're working with just a regular .NET application. Thanks

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• Time with and without OpenMP

  - by was

  I have a question.. I tried to improve a well known program algorithm in C, FOX algorithm for matrix multiplication.. relative link without openMP: (http://web.mst.edu/~ercal/387/MPI/ppmpi_c/chap07/fox.c). The initial program had only MPI and I tried to insert openMP in the matrix multiplication method, in order to improve the time of computation: (This program runs in a cluster and computers have 2 cores, thus I created 2 threads.) The problem is that there is no difference of time, with and without openMP. I observed that using openMP sometimes, time is equivalent or greater than the time without openMP. I tried to multiply two 600x600 matrices. void Local_matrix_multiply( LOCAL_MATRIX_T* local_A /* in */, LOCAL_MATRIX_T* local_B /* in */, LOCAL_MATRIX_T* local_C /* out */) { int i, j, k; chunk = CHUNKSIZE; // 100 #pragma omp parallel shared(local_A, local_B, local_C, chunk, nthreads) private(i,j,k,tid) num_threads(2) { /* tid = omp_get_thread_num(); if(tid == 0){ nthreads = omp_get_num_threads(); printf("O Pollaplasiamos pinakwn ksekina me %d threads\n", nthreads); } printf("Thread %d use the matrix: \n", tid); */ #pragma omp for schedule(static, chunk) for (i = 0; i < Order(local_A); i++) for (j = 0; j < Order(local_A); j++) for (k = 0; k < Order(local_B); k++) Entry(local_C,i,j) = Entry(local_C,i,j) + Entry(local_A,i,k)*Entry(local_B,k,j); } //end pragma omp parallel } /* Local_matrix_multiply */

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• how to return a list using SwingWorker

  - by Ender

  I have an assignment where i have to create an Image Gallery which uses a SwingWorker to load the images froma a file, once the image is load you can flip threw the image and have a slideshow play. I am having trouble getting the list of loaded images using SwingWorker. This is what happens in the background it just publishes the results to a TextArea // In a thread @Override public List<Image> doInBackground() { List<Image> images = new ArrayList<Image>(); for (File filename : filenames) { try { //File file = new File(filename); System.out.println("Attempting to add: " + filename.getAbsolutePath()); images.add(ImageIO.read(filename)); publish("Loaded " + filename); System.out.println("Added file" + filename.getAbsolutePath()); } catch (IOException ioe) { publish("Error loading " + filename); } } return images; } } when it is done I just insert the images in a List<Image> and that is all it does. // In the EDT @Override protected void done() { try { for (Image image : get()) { list.add(image); } } catch (Exception e) { } } Also I created an method that returns the list called getImages() what I need to get is the list from getImages() but doesn't seam to work when I call execute() for example MySwingWorkerClass swingworker = new MySwingWorkerClass(log,list,filenames); swingworker.execute(); imageList = swingworker.getImage() Once it reaches the imageList it doesn't return anything the only way I was able to get the list was when i used the run() instead of the execute() is there another way to get the list or is the run() method the only way?. or perhaps i am not understanding the Swing Worker Class.

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• Mamimum page fetch with maximum bandwith

  - by Ehsan

  Hi I want to create an application like a spider I've implement fetching page as the following code in multi-thread application but there is two problem 1) I want to use my maximum bandwidth to send/receive request, how should I config my request to do so (Like Download Accelerator application and the like) cause I heard the normal application will use 66% of the available bandwidth. 2) I don't know what exactly HttpWebRequest.KeepAlive do, but as its name implies I think i can create a connection to a website and without closing the connection sending another request to that web site using existing connection. does it boost performance or Im wrong public PageFetchResult Fetch() { PageFetchResult fetchResult = new PageFetchResult(); try { HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(URLAddress); HttpWebResponse resp = (HttpWebResponse)req.GetResponse(); Uri requestedURI = new Uri(URLAddress); Uri responseURI = resp.ResponseUri; if (Uri.Equals(requestedURI, responseURI)) { string resultHTML = ""; byte[] reqHTML = ResponseAsBytes(resp); if (!string.IsNullOrEmpty(FetchingEncoding)) resultHTML = Encoding.GetEncoding(FetchingEncoding).GetString(reqHTML); else if (!string.IsNullOrEmpty(resp.CharacterSet)) resultHTML = Encoding.GetEncoding(resp.CharacterSet).GetString(reqHTML); req.Abort(); resp.Close(); fetchResult.IsOK = true; fetchResult.ResultHTML = resultHTML; } else { URLAddress = responseURI.AbsoluteUri; relayPageCount++; if (relayPageCount > 5) { fetchResult.IsOK = false; fetchResult.ErrorMessage = "Maximum page redirection occured."; relayPageCount = 0; return fetchResult; } req.Abort(); resp.Close(); return Fetch(); } } catch (Exception ex) { fetchResult.IsOK = false; fetchResult.ErrorMessage = ex.Message; } return fetchResult; }

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• problm with MANIFEST.MF in jar

  - by Atul

  hi I have created jar in the following folder: /usr/local/bin/niidle.jar. And my MANIFEST.MF file is as follows: Manifest-Version: 1.0 Main-Class: com.ensarm.niidle.web.scraper.NiidleScrapeManager Class-Path: hector-0.6.0-17.jar And I verified that,this 'hector-0.6.0-17.jar' file is also present in the folder: /Projects/EnwelibDatedOct13/Niidle/lib/hector-0.6.0-17.jar I don't want to give full class-path name in MANIFEST.MF file,because I have to run this jar on other's machine,so I gave only jar file name 'Class-Path=hector-0.6.0-17.jar' in MANIFEST.MF file. Inspite of mentioning the Class-Path in MANIFEST.MF file, when I run this using command: java -jar /usr/local/bin/niidle.jar arguments... It is showing error massage: --Exception in thread "main" java.lang.NoClassDefFoundError: me/prettyprint/hector/api/Serializer at com.ensarm.niidle.web.scraper.NiidleScrapeManager.main(NiidleScrapeManager.java:21) Caused by: java.lang.ClassNotFoundException: me.prettyprint.hector.api.Serializer at java.net.URLClassLoader$1.run(URLClassLoader.java:200) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:188) at java.lang.ClassLoader.loadClass(ClassLoader.java:307) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:252) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320) ... 1 more Please give me solution for this error message..

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• Parallel Tasking Concurrency with Dependencies on Python like GNU Make

  - by Brian Bruggeman

  I'm looking for a method or possibly a philosophical approach for how to do something like GNU Make within python. Currently, we utilize makefiles to execute processing because the makefiles are extremely good at parallel runs with changing single option: -j x. In addition, gnu make already has the dependency stacks built into it, so adding a secondary processor or the ability to process more threads just means updating that single option. I want that same power and flexibility in python, but I don't see it. As an example: all: dependency_a dependency_b dependency_c dependency_a: dependency_d stuff dependency_b: dependency_d stuff dependency_c: dependency_e stuff dependency_d: dependency_f stuff dependency_e: stuff dependency_f: stuff If we do a standard single thread operation (-j 1), the order of operation might be: dependency_f -> dependency_d -> dependency_a -> dependency_b -> dependency_e \ -> dependency_c For two threads (-j 2), we might see: 1: dependency_f -> dependency_d -> dependency_a -> dependency_b 2: dependency_e -> dependency_c Does anyone have any suggestions on either a package already built or an approach? I'm totally open, provided it's a pythonic solution/approach. Please and Thanks in advance!

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• How to change internal buffer size of DataInputStream

  - by Gaks

  I'm using this kind of code for my TCP/IP connection: sock = new Socket(host, port); sock.setKeepAlive(true); din = new DataInputStream(sock.getInputStream()); dout = new DataOutputStream(sock.getOutputStream()); Then, in separate thread I'm checking din.available() bytes to see if there are some incoming packets to read. The problem is, that if a packet bigger than 2048 bytes arrives, the din.available() returns 2048 anyway. Just like there was a 2048 internal buffer. I can't read those 2048 bytes when I know it's not the full packet my application is waiting for. If I don't read it however - it'll all stuck at 2048 bytes and never receive more. Can I enlarge the buffer size of DataInputStream somehow? Socket receive buffer is 16384 as returned by sock.getReceiveBufferSize() so it's not the socket limiting me to 2048 bytes. If there is no way to increase the DataInputStream buffer size - I guess the only way is to declare my own buffer and read everything from DataInputStream to that buffer? Regards

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• The CLR has been unable to transition from COM context [...] for 60 seconds

  - by BlueRaja The Green Unicorn

  I am getting this error on code that used to work. I have not changed the code. Here is the full error: The CLR has been unable to transition from COM context 0x3322d98 to COM context 0x3322f08 for 60 seconds. The thread that owns the destination context/apartment is most likely either doing a non pumping wait or processing a very long running operation without pumping Windows messages. This situation generally has a negative performance impact and may even lead to the application becoming non responsive or memory usage accumulating continually over time. To avoid this problem, all single threaded apartment (STA) threads should use pumping wait primitives (such as CoWaitForMultipleHandles) and routinely pump messages during long running operations. And here is the code that caused it: var openFileDialog1 = new System.Windows.Forms.OpenFileDialog(); openFileDialog1.DefaultExt = "mdb"; openFileDialog1.Filter = "Management Database (manage.mdb)|manage.mdb"; //Stalls indefinitely on the following line, then gives the CLR error //one minute later. The dialog never opens. if(openFileDialog1.ShowDialog() == DialogResult.OK) { .... } Yes, I am sure the dialog is not open in the background, and no, I don't have any explicit COM code or unmanaged marshalling or multithreading. I have no idea why the OpenFileDialog won't open - any ideas?

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• Java Servlet: getInitParameter not work in Service()

  - by Gabriele

  I've added some parameters in my web.xml config file, as follow: <context-param> <param-name>service1</param-name> <param-value>http://www.example.com/example2.html</param-value> </context-param> <context-param> <param-name>service2</param-name> <param-value>http://www.example.com/example2.html</param-value> </context-param> ... I try to get the parameter in my servlet, in particular in my service method: protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { System.out.println(this.getServletContext().getInitParameter("service1")); ... but at runtime I have a NullPointerException... How can I get the parameter value included in web.xml? This is the stacktrace: GRAVE: Servlet.service() for servlet DispatcherServlet threw exception java.lang.NullPointerException at javax.servlet.GenericServlet.getServletContext(GenericServlet.java:160) at it.servlethope.DispatcherServlet.service(DispatcherServlet.java:66) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:176) at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:145) at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:92) at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:381) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) at java.lang.Thread.run(Unknown Source) DispatcherServlet.java:66 is the line where I try the getInitParameter()

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• Check if TIFF file is complete

  - by Davi

  I have a FileSystemWatcher monitoring a directory that receives TIF files from a scanning device. Its necessary to check if the scanning process is done and then read a multipage TIF file, otherwise, the FileSystemWatcher will raise the event before the file be fully scanned. I have something like: private void OnFileCreated(...) { while(IsFileLocked(path)) Thread.Sleep(time); // OK to read } This is what is happening: - Scanner creates the file - FileSystemWatcher detects the file, but its in use - Scanner reads the first page to the file - Scanner releases the file - My code leaves the while(FileInUse(path)) - My code reads the incomplete file (problem) - Scanner adds more pages to the file Let's say the scanner is scanning 100 pages, then, when "OK to read", the file will be incomplete (99 pages left). So, its necessary to know if the file is complete or not. Maybe waiting some time to see if the file is modified, but this time span can be up to hours, because the scanner can get idle scanning the same TIF. Other solution would be checking some flag in the TIF file that indicates that the file is not complete(I've looked for this but don't found anything).

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• Producer consumer with qualifications

  - by tgguy

  I am new to clojure and am trying to understand how to properly use its concurrency features, so any critique/suggestions is appreciated. So I am trying to write a small test program in clojure that works as follows: there 5 producers and 2 consumers a producer waits for a random time and then pushes a number onto a shared queue. a consumer should pull a number off the queue as soon as the queue is nonempty and then sleep for a short time to simulate doing work the consumers should block when the queue is empty producers should block when the queue has more than 4 items in it to prevent it from growing huge Here is my plan for each step above: the producers and consumers will be agents that don't really care for their state (just nil values or something); i just use the agents to send-off a "consumer" or "producer" function to do at some time. Then the shared queue will be (def queue (ref [])). Perhaps this should be an atom though? in the "producer" agent function, simply (Thread/sleep (rand-int 1000)) and then (dosync (alter queue conj (rand-int 100))) to push onto the queue. I am thinking to make the consumer agents watch the queue for changes with add-watcher. Not sure about this though..it will wake up the consumers on any change, even if the change came from a consumer pulling something off (possibly making it empty) . Perhaps checking for this in the watcher function is sufficient. Another problem I see is that if all consumers are busy, then what happens when a producer adds something new to the queue? Does the watched event get queued up on some consumer agent or does it disappear? see above I really don't know how to do this. I heard that clojure's seque may be useful, but I couldn't find enough doc on how to use it and my initial testing didn't seem to work (sorry don't have the code on me anymore)

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• C socket programming: client send() but server select() doesn't see it

  - by Fantastic Fourier

  Hey all, I have a server and a client running on two different machines where the client send()s but the server doesn't seem to receive the message. The server employs select() to monitor sockets for any incoming connections/messages. I can see that when the server accepts a new connection, it updates the fd_set array but always returns 0 despite the client send() messages. The connection is TCP and the machines are separated by like one router so dropping packets are highly unlikely. I have a feeling that it's not select() but perhaps send()/sendto() from client that may be the problem but I'm not sure how to go about localizing the problem area. while(1) { readset = info->read_set; ready = select(info->max_fd+1, &readset, NULL, NULL, &timeout); } above is the server side code where the server has a thread that runs select() indefinitely. rv = connect(sockfd, (struct sockaddr *) &server_address, sizeof(server_address)); printf("rv = %i\n", rv); if (rv < 0) { printf("MAIN: ERROR connect() %i: %s\n", errno, strerror(errno)); exit(1); } else printf("connected\n"); sleep(3); char * somemsg = "is this working yet?\0"; rv = send(sockfd, somemsg, sizeof(somemsg), NULL); if (rv < 0) printf("MAIN: ERROR send() %i: %s\n", errno, strerror(errno)); printf("MAIN: rv is %i\n", rv); rv = sendto(sockfd, somemsg, sizeof(somemsg), NULL, &server_address, sizeof(server_address)); if (rv < 0) printf("MAIN: ERROR sendto() %i: %s\n", errno, strerror(errno)); printf("MAIN: rv is %i\n", rv); and this is the client side where it connects and sends messages and returns connected MAIN: rv is 4 MAIN: rv is 4 any comments or insightful insights are appreciated.

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• Diffrernce between BackgroundWorker.ReportProgress() and Control.Invoke()

  - by ohadsc

  What is the difference between options 1 and 2 in the following? private void BGW_DoWork(object sender, DoWorkEventArgs e) { for (int i=1; i<=100; i++) { string txt = i.ToString(); if (Test_Check.Checked) //OPTION 1 Test_BackgroundWorker.ReportProgress(i, txt); else //OPTION 2 this.Invoke((Action<int, string>)UpdateGUI, new object[] {i, txt}); } } private void BGW_ProgressChanged(object sender, ProgressChangedEventArgs e) { UpdateGUI(e.ProgressPercentage, (string)e.UserState); } private void UpdateGUI(int percent, string txt) { Test_ProgressBar.Value = percent; Test_RichTextBox.AppendText(txt + Environment.NewLine); } Looking at reflector, the Control.Invoke() appears to use: this.FindMarshalingControl().MarshaledInvoke(this, method, args, 1); whereas BackgroundWorker.Invoke() appears to use: this.asyncOperation.Post(this.progressReporter, args); (I'm just guessing these are the relevant function calls.) If I understand correctly, BGW Posts to the WinForms window its progress report request, whereas Control.Invoke uses a CLR mechanism to invoke on the right thread. Am I close? And if so, what are the repercussions of using either ? Thanks

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• NSTimer as a timeout mechanism

  - by alexantd

  I'm pretty sure this is really simple, and I'm just missing something obvious. I have an app that needs to download data from a web service for display in a UITableView, and I want to display a UIAlertView if the operation takes more than X seconds to complete. So this is what I've got (simplified for brevity): MyViewController.h @interface MyViewController : UIViewController <UITableViewDelegate, UITableViewDataSource> { NSTimer *timer; } @property (nonatomic, retain) NSTimer *timer; MyViewController.m @implementation MyViewController @synthesize timer; - (void)viewDidLoad { timer = [NSTimer scheduledTimerWithTimeInterval:20 target:self selector:@selector(initializationTimedOut:) userInfo:nil repeats:NO]; [self doSomethingThatTakesALongTime]; [timer invalidate]; } - (void)doSomethingThatTakesALongTime { sleep(30); // for testing only // web service calls etc. go here } - (void)initializationTimedOut:(NSTimer *)theTimer { // show the alert view } My problem is that I'm expecting the [self doSomethingThatTakesALongTime] call to block while the timer keeps counting, and I'm thinking that if it finishes before the timer is done counting down, it will return control of the thread to viewDidLoad where [timer invalidate] will proceed to cancel the timer. Obviously my understanding of how timers/threads work is flawed here because the way the code is written, the timer never goes off. However, if I remove the [timer invalidate], it does.

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• Scala newbie vproducer/consumer attempt running out of memory

  - by Nick

  I am trying to create a producer/consumer type Scala app. The LoopControl just sends a message to the MessageReceiver continually. The MessageReceiver then delegates work to the MessageCreatorActor (whose work is to check a map for an object, and if not found create one and start it up). Each MessageActor created by this MessageCreatorActor is associated with an Id. Eventually this is where I want to do business logic. But I run out of memory after 15 minutes. Its finding the cached actors,but quickly runs out of memory. Any help is appreciated. Or any one has any good code on producers consumers doing real stuff (not just adding numbers), please post. import scala.actors.Actor import java.util.HashMap import scala.actors.Actor._ case object LoopControl case object MessageReceiver case object MessageActor case object MessageActorCreator class MessageReceiver(msg: String) extends Actor { var messageActorMap = new HashMap[String, MessageActor] val messageCreatorActor = new MessageActorCreator(null, null) def act() { messageCreatorActor.start loop { react { case MessageActor(messageId) => if (msg.length() > 0) { var messageActor = messageActorMap.get(messageId); if(messageActor == null) { messageCreatorActor ! MessageActorCreator(messageId, messageActorMap) }else { messageActor ! MessageActor } } } } } } case class MessageActorCreator(msg:String, messageActorMap: HashMap[String, MessageActor]) extends Actor { def act() { loop { react { case MessageActorCreator(messageId, messageActorMap) => if(messageId != null ) { var messageActor = new MessageActor(messageId); messageActorMap.put(messageId, messageActor) println(messageActorMap) messageActor.start messageActor ! MessageActor } } } } } class LoopControl(messageReceiver:MessageReceiver) extends Actor { var count : Int = 0; def act() { while (true) { messageReceiver ! MessageActor ("00-122-0X95-FEC0" + count) //Thread.sleep(100) count = count +1; if(count > 5) { count = 0; } } } } case class MessageActor(msg: String) extends Actor { def act() { loop { react { case MessageActor => println() println("MessageActor: Got something-> " + msg) } } } } object messages extends Application { val messageReceiver = new MessageReceiver("bootstrap") val loopControl = new LoopControl(messageReceiver) messageReceiver.start loopControl.start }

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• How to add deploy.jar to classpath?

  - by dma_k

  I am facing the problem: I need to add ${java.home}/lib/deploy.jar JAR file to classpath in the runtime (dynamically from java). The solution with Thread#setContextClassLoader(ClassLoader) (mentioned here) does not work because of this bug (if somebody can explain what is really a problem – you are welcome). The solution with -Xbootclasspath/a:"%JAVA_HOME%/jre/lib/deploy.jar" does not work well for me, because I want to have "pure executable jar" as a deliverable: no wrapping scripts please (more over %JAVA_HOME% may not be defined in user's environment in Windows for example, plus I need to write a script per platform) The solution with merging deploy.jar file into my deliverable works only if I make a build on Windows platform. Unfortunately, when the deliverable is produced on build server running on Linux, I got Linux-dependant JAR, which does not execute on Windows – it fails with the trace below. I have read How the Java Launcher Finds Classes and Java programming dynamics: Java classes and class loading articles but I've got no extra ideas, how to correctly handle this situation. Any advices or solutions are very welcomed. Trace: java.lang.NoClassDefFoundError: Could not initialize class com.sun.deploy.config.Config at com.sun.deploy.net.proxy.UserDefinedProxyConfig.getBrowserProxyInfo(UserDefinedProxyConfig.java:43) at com.sun.deploy.net.proxy.DynamicProxyManager.reset(DynamicProxyManager.java:235) at com.sun.deploy.net.proxy.DeployProxySelector.reset(DeployProxySelector.java:59) ... java.lang.NullPointerException at com.sun.deploy.net.proxy.DynamicProxyManager.getProxyList(DynamicProxyManager.java:63) at com.sun.deploy.net.proxy.DeployProxySelector.select(DeployProxySelector.java:166)

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• I am not able to kill a child process using TerminateProcess

  - by user1681210

  I have a problem to kill a child process using TerminateProcess. I call to this function and the process still there (in the Task Manager) This piece of code is called many times launching the same program.exe many times and these process are there in the task manager which i think is not good. sorry, I am quiet new in c++ I will really appreciate any help. thanks a lot!! the code is the following: STARTUPINFO childProcStartupInfo; memset( &childProcStartupInfo, 0, sizeof(childProcStartupInfo)); childProcStartupInfo.cb = sizeof(childProcStartupInfo); childProcStartupInfo.hStdInput = hFromParent; // stdin childProcStartupInfo.hStdOutput = hToParent; // stdout childProcStartupInfo.hStdError = hToParentDup; // stderr childProcStartupInfo.dwFlags = STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW; childProcStartupInfo.wShowWindow = SW_HIDE; PROCESS_INFORMATION childProcInfo; /* for CreateProcess call */ bOk = CreateProcess( NULL, // filename pCmdLine, // full command line for child NULL, // process security descriptor */ NULL, // thread security descriptor */ TRUE, // inherit handles? Also use if STARTF_USESTDHANDLES */ 0, // creation flags */ NULL, // inherited environment address */ NULL, // startup dir; NULL = start in current */ &childProcStartupInfo, // pointer to startup info (input) */ &childProcInfo); // pointer to process info (output) */ CloseHandle( hFromParent ); CloseHandle( hToParent ); CloseHandle( hToParentDup ); CloseHandle( childProcInfo.hThread); CloseHandle( childProcInfo.hProcess); TerminateProcess( childProcInfo.hProcess ,0); //this is not working, the process thanks

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• Checking if a console application is still running using the Process class

  - by Ced

  I'm making an application that will monitor the state of another process and restart it when it stops responding, exits, or throws an error. However, I'm having trouble to make it reliably check if the process (Being a C++ Console window) has stopped responding. My code looks like this: public void monitorserver() { while (true) { server.StartInfo = new ProcessStartInfo(textbox_srcdsexe.Text, startstring); server.Start(); log("server started"); log("Monitor started."); while (server.Responding) { if (server.HasExited) { log("server exitted, Restarting."); break; } log("server is running: " + server.Responding.ToString()); Thread.Sleep(1000); } log("Server stopped responding, terminating.."); try { server.Kill(); } catch (Exception) { } } } The application I'm monitoring is Valve's Source Dedicated Server, running Garry's Mod, and I'm over stressing the physics engine to simulate it stopping responding. However, this never triggers the process class recognizing it as 'stopped responding'. I know there are ways to directly query the source server using their own protocol, but i'd like to keep it simple and universal (So that i can maybe use it for different applications in the future). Any help appreciated

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• How do I keep from running out of memory on graphics for an Android app?

  - by user279112

  I've been working on an Android app in Eclipse, and so far, my program hasn't really grown past midget size. However I've already run into an issue with an Out of Memory error. You see, I've been using graphics comprised solely of bitmaps and PNGs in this program, and recently, when I tried to add a little bit more functionality to the program (mainly including a few more bitmaps and causing an extra sprite to be created), it started crashing in the graphics thread's constructor - sprite's constructor. When I tracked the problem down, it turned out to be an Out of Memory error that is seemingly caused by adding too many picture files to the program and creating Drawables out of them. This would be a problem, as I really don't have that many picture resources worked into that program...maybe 20 or so. I haven't even started to include sound yet. These images aren't all that fancy. My questions are this: 1) Are programs for the Android phone really that limited on how much memory they can employ, or is it probably something other than the 20-30 resource pictures causing that error? 2) If the memory for Android apps is so awful it can't even handle 20-30 picture resources being loaded into Drawables that exist at the same time, then how in the world are you supposed to make decent graphics and sound for that thing? Thanks.

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• Silverlight performance with many loaded controls

  - by gius

  I have a SL application with many DataGrids (from Silverlight Toolkit), each on its own view. If several DataGrids are opened, changing between views (TabItems, for example) takes a long time (few seconds) and it freezes the whole application (UI thread). The more DataGrids are loaded, the longer the change takes. These DataGrids that slow the UI chanage might be on other places in the app and not even visible at that moment. But once they are opened (and loaded with data), they slow showing other DataGrids. Note that DataGrids are NOT disposed and then recreated again, they still remain in memory, only their parent control is being hidden and visible again. I have profiled the application. It shows that agcore.dll's SetValue function is the bottleneck. Unfortunately, debug symbols are not available for this Silverlight native library responsible for drawing. The problem is not in the DataGrid control - I tried to replace it with XCeed's grid and the performance when changing views is even worse. Do you have any idea how to solve this problem? Why more opened controls slow down other controls? I have created a sample that shows this issue: http://cenud.cz/PerfTest.zip UPDATE: Using VS11 profiler on the sample provided suggests that the problem could be in MeasureOverride being called many times (for each DataGridCell, I guess). But still, why is it slower as more controls are loaded elsewhere? Is there a way to improve the performance?

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