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  • ExecutorSerrvice memory leak on exception

    - by TofuBeer
    I am having a hard time tracking this down since the profiler keeps crashing (hotspot error). Before I go too deep into figuring it out I'd like to know if I really have a problem or not :-) I have a few thread pools created via: Executors.newFixedThreadPool(10); The threads connect to different web sites and, on occasion, I get connection refused and wind up throwing an exception. When I later on call Future.get() to get the result it will then catch the ExecutionException that wraps the exception that was thrown when the connection could not be made. The program uses a fairly constant amount of memory up until the point in time that the exceptions get thrown (they tend to happen in batches when a particular site is overloaded). After that point the memory again remains constant but at a higher level. So my question is along the lines of is the memory behaviour (reported by "top" on Unix) expected because the exceptions just triggered something or do I probably have an actual leak that I'll need to track down? Additionally when Future.get() throws an exception is there anything else I need to do besides catch the exception (such as call Future.cancel() on it)?

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  • TransactionRequiredException on OptimisticLockException

    - by João Madureira Pires
    Hi there. I have the following class that generates sequencial Card Numbers. I'm trying to recover from OptimisticLockException, by calling recursively the same method. however, i'm getting TransactionRequiredException. Dows anyone knows how to recover from OptimisticLockException in my case? Thanks a lot in advance @Name("simpleAutoIncrementGenerator") public class SimpleAutoIncrementGenerator extends CardNumberGenerator{ private static final long serialVersionUID = 2869548248468809665L; private int numberOfRetries = 0; @Override public String generateNextNumber(CardInstance cardInstance, EntityManager entityManager) { try{ EntityCard card = (EntityCard)entityManager.find(EntityCard.class, cardInstance.getId()); if(card != null){ String nextNumber = ""; String currentNumber = card.getCurrentCardNumber(); if(currentNumber != null && !currentNumber.isEmpty()){ Long numberToInc = Long.parseLong(currentNumber); numberToInc ++; nextNumber = String.valueOf(numberToInc); card.setCurrentCardNumber(nextNumber); // this is just to cause a OptimisticLock Exception try { Thread.sleep(4000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } entityManager.persist(card); entityManager.flush(); return nextNumber; } } }catch (OptimisticLockException oLE) { System.out.println("\n\n\n\n OptimisticLockException \n\n\n\n"); if(numberOfRetries < CentralizedConfig.CARD_NUMBER_GENERATOR_MAX_TRIES){ numberOfRetries ++; return generateNextNumber(cardInstance,entityManager); } }catch (TransactionRequiredException trE) { System.out.println("\n\n\n\n TransactionRequiredException \n\n\n\n"); if(numberOfRetries < CentralizedConfig.CARD_NUMBER_GENERATOR_MAX_TRIES){ numberOfRetries ++; return generateNextNumber(cardInstance,entityManager); } }catch (StaleObjectStateException e) { System.out.println("\n\n\n\n StaleObjectStateException \n\n\n\n"); if(numberOfRetries < CentralizedConfig.CARD_NUMBER_GENERATOR_MAX_TRIES){ numberOfRetries ++; return generateNextNumber(cardInstance,entityManager); } } return null; } }

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  • Long running method causing race condition

    - by keeleyt83
    Hi, I'm relatively new with hibernate so please be gentle. I'm having an issue with a long running method (~2 min long) and changing the value of a status field on an object stored in the DB. The pseudo-code below should help explain my issue. public foo(thing) { if (thing.getStatus() == "ready") { thing.setStatus("finished"); doSomethingAndTakeALongTime(); } else { // Thing already has a status of finished. Send the user back a message. } } The pseudo-code shouldn't take much explanation. I want doSomethingAndTakeALongTime() to run, but only if it has a status of "ready". My issue arises whenever it takes 2 minutes for doSomethingAndTakeALongTime() to finish and the change to thing's status field doesn't get persisted to the database until it leaves foo(). So another user can put in a request during those 2 minutes and the if statement will evaluate to true. I've already tried updating the field and flushing the session manually, but it didn't seem to work. I'm not sure what to do from here and would appreciate any help. PS: My hibernate session is managed by spring.

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  • Strategies for dealing with Circular references caused by JPA relationships?

    - by ams
    I am trying to partition my application into modules by features packaged into separate jars such as feature-a.jar, feature-b.jar, ... etc. Individual feature jars such as feature-a.jar should contain all the code for a feature a including jpa entities, business logic, rest apis, unit tests, integration test ... etc. The problem I am running into is that bi-directional relationships between JPA entities cause circular references between the jar files. For example Customer entity should be in customer.jar and the Order should be in order.jar but Customer references order and order references customer making it hard to split them into separate jars / eclipse projects. Options I see for dealing with the circular dependencies in JPA entities: Option 1: Put all the entities into one jar / one project Option 2: Don't map certain bi-directianl relationships to avoid circular dependencies across projects. Questions: What rules / principles have you used to decide when to do bi-directional mapping vs. not? Have you been able to break jpa entities into their own projects / jar by features if so how did you avoid the circular dependencies issues?

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  • Messaging strategies to connect different systems

    - by n002213f
    I have a system to handle Applications online and a different system to send SMS/Email notifications to applicants on completion using web services. I can't guarantee the availability of the SMS/Email gateway. Option 1 After an application is complete, place a message on a JMS queue. A Message Driven bean receives the message and make a call for the web service, if it fails leave the message on the queue. I suspect (please correct if incorrect) that if the gate way is offline the continuosly try to send the message which might use up valuable resources. Can the above option be refined are are there any other messaging strategies that can be used?

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  • How to create updateable panel using AjaxLink of Wicket?

    - by Arne
    I try to realize a link (in fact many links) that update a table in an website using an AjaxLink of Wicket. But I fail, the table is never updated (I have "setOutputMarkupId(true)" and call "addComponent", but there must be something other thats wrong). How can I realize a panel with a number of links and a table that displays dynamic data, dependent on the link clicked? Can someone give an example (Maybe two links, when the first one is clicked the table displays two random numbers from 1-10, when the second is clicked the table displays random numbers from 1-100)? Without reloading the entire page, but only the html for the table?

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  • Best way to get a Web Service to return a database result as XML?

    - by John
    I am building a webservice using jax-rs and querying a DB2 z/OS database with SQLJ and getting the result set as an arraylist. I would like to return this list as XML, but not sure how to do it. Does anyone have an example of returning a result set as XML and is using an Arraylist the best way to do this? Should I use JAXB? if so how?

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  • Casting to specific class in HQL

    - by bungrudi
    My situation is like this.. (note: for those who work with JBPM might already familiar with following data structures and HB mapping) Class LongInstance extends from VariableInstance, with the mapping for field "value" overridden in LongInstance. The mapping for VariableInstance is here and for LongInstance here. VariableInstance is polymorphically mapped to a collection in TokenVariableMap, the mapping is here. The question: how can I query the polymorphic collection using specific/overridden property of the member class? I'm looking for something like this "... from TokenVariableMaps tvm left join fetch tvm.variableInstances tvi where cast(tvi as LongInstance).value in(:vars)"

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  • Spring Web application internal visual monitoring heap space and permgen.

    - by Veniamin
    If I have created web application used Spring framework(based on maven), can I include some module/dependency/plugin into my app to monitor Heap space, Permgen, etc. It whould be greate to get some charts output likes as in VisuaVM. For example: http://localhost:8080/monitoring = Including something likes VisualVM I have found next dependency without link to repo: <dependency> <groupId>com.sun.tools.visualvm</groupId> <artifactId>core</artifactId> <version>1.3.3</version> </dependency> How to use it?

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  • how to share a variable between two threads

    - by prmatta
    I just inherited some code, two threads within this code need to perform a system task. One thread should do the system task before the other thread. They should not be performing the system task together. The two threads do not have references to each other. Now, I know I can use some sort of a semaphore to achieve this. But my question is what is the right way to get both threads to access this semaphore. I could create a static variable/method a new class : public class SharedSemaphore { private static Semaphore s = new Semaphore (1, true); public static void performSystemTask () { s.acquire(); } public static void donePerformingSystemTask() { s.release(); } } This would work (right?) but this doesn't seem like the right thing to do. Because, the threads now have access to a semaphore, without ever having a reference to it. This sort of thing doesn't seem like a good programming practice. Am I wrong?

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  • vlcj not displaying the video

    - by Cássio Eudardo
    I'm using vlcj to play video, but the video doesn't display on some computers(i tested in 4 and worked on 2, all windows), on 1 it displays the button but not the video and on the other it just display a gray background without the button. I tested .wmv and .avi files. I'm using the following code: public class Video extends JFrame implements WindowListener{ private JPanel contentPane; private JButton btnClose; private Dimension size; private float aspectRatio; private EmbeddedMediaPlayer mediaPlayer; public Video() { try { size = Toolkit.getDefaultToolkit().getScreenSize(); aspectRatio = (float)size.width/size.height; String file = "..."; btnClose = new JButton("X"); btnClose.addActionListener(new ActionListener() {...}); btnClose.setBounds(640 - 50, 10, 40, 40); setBounds(size.width/2 - 320, (int)(size.height - 40*aspectRatio) - 250, 640, 200); contentPane = new JPanel(); contentPane.setLayout(null); setContentPane(contentPane); WindowsCanvas surface = new WindowsCanvas(); contentPane.setBounds(0, 0, 640, 200); surface.setBounds(0, 0, 640, 200); MediaPlayerFactory factory = new MediaPlayerFactory(new String("--no-video-title-show")); mediaPlayer = factory.newEmbeddedMediaPlayer(); surface.addMouseListener(new MouseListener() {...}); contentPane.add(btnClose); contentPane.add(surface); setVisible(true); mediaPlayer.setVideoSurface(factory.newVideoSurface(surface)); mediaPlayer.setRepeat(true); mediaPlayer.playMedia(file); } catch(Exception e) { } }}

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  • how to make components visible in a transparent JFrame

    - by Md. Mahmudul Hasan
    I have some JButtons in a JFrame (its layout is null). The background Color of the buttons are set Black. I have made the JFrame Transparent by using this code. AWTUtilities.setWindowOpacity(this, 0); But the problem is it also makes all the buttons transparent as well. I don't want that. I want to see the buttons remaining black but the other portions of the JFrame becoming transparent (so that I can see the desktop background). Please someone help me. Thanks in advance.

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  • Use ObjectOutputStream and FileOutputStream with FileWriter

    - by wishi
    Hi! Is there any way to use ObjectOutputStream like this: <tag>output of the ObjectOutputStream</tag> If I try: FileOutputStream fos = new FileOutputStream(filename); ObjectOutputStream oos = new ObjectOutputStream(fos); FileWriter fw = new FileWriter(fos); And for example: fw.write("<tag>"); oos.write(cool_object); fw.wrote("</tag>"); I don't get that result. It seems the ObjectOutputStream overwrites the file completly each and every time.

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  • h:graphicimage not working in c:foreach

    - by Muneeswaran Balasubramanian
    I have used c:forEach loop for display the list of images using h:graphicImage. But I can't display the images. I have the h:commandLink also in my page. The image have to be displayed at the time of form inititalization. But its not working. But after click the h:commandlink, the images are displayed properly. Before that it shows the image not found text (alt message). I have used h:graphicImage tag like below <c:forEach items="#{Sample.imageList}" var="images" varstatus="imageStatus"> <h:graphicimage id="image" url="#{images}" alt="Image Not Found"/> </c:forEach> What I do wrong in that and how can I achieve that?

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  • Identifying the GeoPoint that trigger an onTap call

    - by Akroy
    I'm developing a Google Maps app on Android. I have a number of GeoPoints that I'm displaying by adding them as OverlayItems to an ItemizedOverlay. This works well for displaying them and bringing up a nice box when I click them, however I'm trying to put info in the box it brings up. Thus, I've extended ItemizedOverlay with my own class, and I'm overriding onTap (final GeoPoint p, final MapView mapView). At first I thought that this would be very simple, as one of the parameters is the GeoPoint, so I would know exactly which GeoPoint was clicked. However, from what I can tell, the GeoPoint argument there is the GeoPoint for where the user actually touched. Given the range the user can touch and still trigger the onTap, that GeoPoint isn't very helpful for knowing precisely which GeoPoint was actually touched. I'm currently checking the parameter GeoPoint against all my existing GeoPoints and seeing which it's closest to. This seems like a super hacky abstraction inversion. Is there a better way to know what was actually tapped?

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  • final and private static

    - by xdevel2000
    I read that doing: public final void foo() {} is equals to: private static void foo() {} both meaning that the method is not overridable! But I don't see the equivalence if a method is private it's automatically not accessible...

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  • How to get icons for entities from eclipse?

    - by fastcodejava
    I am writing an eclipse plugin. How do I get the various images from eclipse library? So I don't have have keep a local set of images for the standard entities, e.g classes, interfaces, junits, etc. EDIT : I used PlatformUI.getWorkbench().getSharedImages().getImage(ISharedImages.IMG_OBJ_FILE) from the article : http://www.eclipse.org/articles/Article-Using%20Images%20In%20Eclipse/Using%20Images%20In%20Eclipse.html. That did not work.

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  • Android HTTP Connection

    - by Ubersoldat
    Can anybody tell my why this doesn't work in the Android emulator? From the browser I have access and the server is internal. All I can think of is that I'm missing some configuration on my app so it can access the network layer. try { InetAddress server = Inet4Address.getByName("thehost"); //Doesn't work either //or InetAddress server2 = Inet4Address.getByAddress(new String("192.168.1.30").getBytes()); if(server.isReachable(5000)){ Log.d(TAG, "Ping!"); } Socket clientsocket = new Socket(server, 8080); } catch (UnknownHostException e) { Log.e(TAG, "Server Not Found"); } catch (IOException e) { Log.e(TAG, "Couldn't open socket"); } Throws an UnknownHostException Thanks

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  • JTable data only shown after scrolling

    - by Christian 'fuzi' Orgler
    I wrote a method, that creates my DefaultTableModel and there I'm going to add my records. When I set the model to my JTable, the data rows are blank. After scrolling the data gets displayed correct. How can I avoid this and display the data from the first moment? EDIT: I imported the javax.swing.table.DefaultTableModel -- is this correct? private DefaultTableModel _dtm; private void loadTable(Vector<Member> members) { loadTableModel(); try { lbl_state.setText("Please wait"); for (Member actMember : members) { String gender = ""; if (actMember.getGender() == MemberView.MEMBER_MALE) { gender = "männlich"; } else { gender = "weiblich"; } _dtm.addRow(new Object[]{ actMember.getNname(), actMember.getVname(), actMember.getCity(), actMember.getStreet(), actMember.getPlz(), actMember.getMail(), actMember.getPhonenumber(), actMember.getBirthdayString(), actMember.getStartDateString(), gender, actMember.getBankname(), actMember.getAccountnumber(), actMember.getBanknumber(), actMember.getGroup().toString(), (actMember.hasAccess() ? "JA" : "NEIN"), actMember.getWriteDateString(), (actMember.hasDrinkAbo() ? "JA" : "NEIN") }); } } catch (Exception ex) { System.err.println(ex.getMessage()); } tbl_results.setModel(_dtm); } private void loadTableModel() { _dtm = new DefaultTableModel(new Object[]{"Nachname", "Vorname", "Ort", "Straße", "PLZ", "E-Mail", "Telefon", "Geburtsdatum", "Beitrittsdatum", "Geschlecht", "Bankname", "Kontonummer", "Bankleitzahl", "Gruppe", "hat Zugriff", "Einschreibdatum", "Getränkeabo"}, 0); tbl_results.setAutoResizeMode(JTable.AUTO_RESIZE_ALL_COLUMNS); }

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  • longest common subsequence

    - by davit-datuashvili
    i have following code public class LCS1 { public static String lcs(String a,String b) { String x; String y; int alen=a.length(); int blen=b.length(); if (alen==0 || blen==0) { return ""; } else if (a.charAt(alen-1)==b.charAt(blen-1)) { return lcs(a.substring(0,alen-1),b.substring(0,blen-1)); } else { x=lcs(a,b.substring(0,blen-1)); y=lcs(a.substring(0,alen-1),b); } return (x.length()>y.length()) ? x : y; } public static void main(String[]args){ String a="computer"; String b="houseboat"; System.out.println(lcs(a,b)); } } it should return "out" but returns nothing what is problem?

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