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  • DirectX 10 Instancing Problem (objects cannot be seen)

    - by Riffraff
    Right now I'm trying to implement an area that is filled with vegetation. I have tried mesh version and right now I'm trying to implement instancing version but I cannot manage to make it work. I can't see any object. I search for any problem of buffers with FAILED() and D3D10_CREATE_DEVICE_DEBUG but they didn't help me either. Right now I don't even know which part of my code to share to explain my problem.

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  • Development Approach: User Interface In or Domain Model Out?

    - by Berin Loritsch
    While I've never delivered anything using Smalltalk, my brief time playing with it has definitely left its mark. The only way to describe the experience is MVC the way it was meant to be. Essentially, all the heavy lifting for your application is done in the business objects (or domain model if you are so inclined). The standard controls are bound to the business objects in some way. For example, a text box is mapped to an object's field (the field itself is an object so it's easy to do). A button would mapped to a method. This is all done with a very simple and natural API. We don't have to think about binding objects, etc. It just works. Yet, in many newer languages and APIs you are forced to think from the outside in. First with C++ and MFC, and now with C# and WPF, Microsoft has gotten it's developer world hooked on GUI builders where you build your application by implementing event handlers. Java Swing development isn't so different, only you are writing the code to instantiate the controls on the form yourself. For some projects, there may never even be a domain model--just event handlers. I've been in and around this model for most of my carreer. Each way forces you to think differently. With the Smalltalk approach, your domain is smart while your GUI is dumb. With the default VisualStudio approach, your GUI is smart while your domain model (if it exists) is rather anemic. Many developers that I work with see value in the Smalltalk approach, and try to shoehorn that approach into the VisualStudio environment. WPF has some dynamic binding features that makes it possible; but there are limitations. Inevitably some code that belongs in the domain model ends up in the GUI classes. So, which way do you design/develop your code? Why? GUI first. User interaction is paramount. Domain first. I need to make sure the system is correct before we put a UI on it. There's pros and cons for either approach. Domain model fits in there with crystal cathedrals and pie in the sky. GUI fits in there with quick and dirty (sometimes really dirty). And for an added bonus: How do you make sure the code is maintainable?

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  • Why does std::map operator[] create an object if the key doesn't exist?

    - by n1ck
    Hi, I'm pretty sure I already saw this question somewhere (comp.lang.c++? Google doesn't seem to find it there either) but a quick search here doesn't seem to find it so here it is: Why does the std::map operator[] create an object if the key doesn't exist? I don't know but for me this seems counter-intuitive if you compare to most other operator[] (like std::vector) where if you use it you must be sure that the index exists. I'm wondering what's the rationale for implementing this behavior in std::map. Like I said wouldn't it be more intuitive to act more like an index in a vector and crash (well undefined behavior I guess) when accessed with an invalid key? Refining my question after seeing the answers: Ok so far I got a lot of answers saying basically it's cheap so why not or things similar. I totally agree with that but why not use a dedicated function for that (I think one of the comment said that in java there is no operator[] and the function is called put)? My point is why doesn't map operator[] work like a vector? If I use operator[] on an out of range index on a vector I wouldn't like it to insert an element even if it was cheap because that probably mean an error in my code. My point is why isn't it the same thing with map. I mean, for me, using operator[] on a map would mean: i know this key already exist (for whatever reason, i just inserted it, I have redundancy somewhere, whatever). I think it would be more intuitive that way. That said what are the advantage of doing the current behavior with operator[] (and only for that, I agree that a function with the current behavior should be there, just not operator[])? Maybe it give clearer code that way? I don't know. Another answer was that it already existed that way so why not keep it but then, probably when they (the ones before stl) choose to implement it that way they found it provided an advantage or something? So my question is basically: why choose to implement it that way, meaning a somewhat lack of consistency with other operator[]. What benefit do it give? Thanks

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  • Rotating object along bezier curve: not rotating enough?

    - by Paul
    I tried to follow the instructions from the threads on the forum (Cocos2d rotating sprite while moving with CCBezierBy) with Unity, in order to rotate my object as it moves along a bezier curve. But it does not rotate enough, the angle is too low, it goes up to 6 instead of 90 for example, as you can see on this image (the y eulerAngle is at 6, I would expect it to be around 90 with this curve) : Would you know why it does this? And how to make the rotation toward the next point? Here is the code (in c# with Unity) : (I am comparing x and z to get the angle, and adding the angle to eulerAngles.y so that it rotates around the y axis) void Update () { if ( Input.GetKey("d") ) start = true; if ( start ){ myTime = Time.time; start = false; } float theTime = (Time.time - myTime) *0.5f; if ( theTime < 1 ) { car.position = Spline.Interp( myArray, theTime );//creates the bezier curve counterBezier += Time.deltaTime; //compare 2 positions after 0.1f if ( counterBezier > 0.1f ){ counterBezier = 0; cbDone = false; newpos = car.position; float angle = Mathf.Atan2(newpos.z - oldpos.z, newpos.x - oldpos.x); angle += car.eulerAngles.y; car.eulerAngles = new Vector3(0,angle,0); } else if ( counterBezier > 0 && !cbDone ){ oldpos = car.position; cbDone = true; } Thanks

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  • Box Collider isn't rotating with Game Object

    - by pek
    I have a method that creates a room by instantiating a prefab, places it in a grid and the re-sizes the collider based on a room definition (location in grid, rotation, width and height). Here is the method: public void CreateRoom(RoomAction action) { GameObject roomGameObject = Instantiate(this.roomPrefab, Vector3.zero, action.RoomPrefab.transform.rotation) as GameObject; roomGameObject.transform.parent = this.transform; roomGameObject.transform.localPosition = new Vector3(action.MansionOffsetX, 0, -action.MansionOffsetY) * this.blockSize; roomGameObject.transform.localPosition += new Vector3((action.Room.Width * this.blockSize) / 2, 0, -((action.Room.Height * this.blockSize) / 2)); BoxCollider roomCollider = roomGameObject.GetComponent<BoxCollider>(); roomCollider.isTrigger = true; roomCollider.center = new Vector3(0, this.height / 2, 0); roomCollider.size = new Vector3(action.Room.Width * this.blockSize, this.height, action.Room.Height * this.blockSize); roomGameObject.transform.RotateAroundLocal(roomGameObject.transform.up, Mathf.Deg2Rad * -90 * action.Rotation); } The problem I'm having is that, while the room rotates correctly, but for some reason, the collider isn't rotating with the game object. Here is a screenshot: Any idea on what am I doing wrong?

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  • Scale a game object to Bounds

    - by Spikeh
    I'm trying to scale a lot of dynamically created game objects in Unity3D to the bounds of a sphere collider, based on the size of their current mesh. Each object has a different scale and mesh size. Some are bigger than the AABB of the collider, and some are smaller. Here's the script I've written so far: private void ScaleToCollider(GameObject objectToScale, SphereCollider sphere) { var currentScale = objectToScale.transform.localScale; var currentSize = objectToScale.GetMeshHierarchyBounds().size; var targetSize = (sphere.radius * 2); var newScale = new Vector3 { x = targetSize * currentScale.x / currentSize.x, y = targetSize * currentScale.y / currentSize.y, z = targetSize * currentScale.z / currentSize.z }; Debug.Log("{0} Current scale: {1}, targetSize: {2}, currentSize: {3}, newScale: {4}, currentScale.x: {5}, currentSize.x: {6}", objectToScale.name, currentScale, targetSize, currentSize, newScale, currentScale.x, currentSize.x); //DoorDevice_meshBase Current scale: (0.1, 4.0, 3.0), targetSize: 5, currentSize: (2.9, 4.0, 1.1), newScale: (0.2, 5.0, 13.4), currentScale.x: 0.125, currentSize.x: 2.869114 //RedControlPanelForAirlock_meshBase Current scale: (1.0, 1.0, 1.0), targetSize: 5, currentSize: (0.0, 0.3, 0.2), newScale: (147.1, 16.7, 25.0), currentScale.x: 1, currentSize.x: 0.03400017 objectToScale.transform.localScale = newScale; } And the supporting extension method: public static Bounds GetMeshHierarchyBounds(this GameObject go) { var bounds = new Bounds(); // Not used, but a struct needs to be instantiated if (go.renderer != null) { bounds = go.renderer.bounds; // Make sure the parent is included Debug.Log("Found parent bounds: " + bounds); //bounds.Encapsulate(go.renderer.bounds); } foreach (var c in go.GetComponentsInChildren<MeshRenderer>()) { Debug.Log("Found {0} bounds are {1}", c.name, c.bounds); if (bounds.size == Vector3.zero) { bounds = c.bounds; } else { bounds.Encapsulate(c.bounds); } } return bounds; } After the re-scale, there doesn't seem to be any consistency to the results - some objects with completely uniform scales (x,y,z) seem to resize correctly, but others don't :| Its one of those things I've been trying to fix for so long I've lost all grasp on any of the logic :| Any help would be appreciated!

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  • SQL SERVER – Get Schema Name from Object ID using OBJECT_SCHEMA_NAME

    - by pinaldave
    Sometime a simple solution have even simpler solutions but we often do not practice it as we do not see value in it or find it useful. Well, today’s blog post is also about something which I have seen not practiced much in codes. We are so much comfortable with alternative usage that we do not feel like switching how we query the data. I was going over forums and I noticed that at one place user has used following code to get Schema Name from ObjectID. USE AdventureWorks2012 GO SELECT s.name AS SchemaName, t.name AS TableName, s.schema_id, t.OBJECT_ID FROM sys.Tables t INNER JOIN sys.schemas s ON s.schema_id = t.schema_id WHERE t.name = OBJECT_NAME(46623209) GO Before I continue let me say I do not see anything wrong with this script. It is just fine and one of the way to get SchemaName from Object ID. However, I have been using function OBJECT_SCHEMA_NAME to get the schema name. If I have to write the same code from the beginning I would have written the same code as following. SELECT OBJECT_SCHEMA_NAME(46623209) AS SchemaName, t.name AS TableName, t.schema_id, t.OBJECT_ID FROM sys.tables t WHERE t.name = OBJECT_NAME(46623209) GO Now, both of the above code give you exact same result. If you remove the WHERE condition it will give you information of all the tables of the database. Now the question is which one is better – honestly – it is not about one is better than other. Use the one which you prefer to use. I prefer to use second one as it requires less typing. Let me ask you the same question to you – which method to get schema name do yo use? and Why? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL System Table, SQL Tips and Tricks, T SQL, Technology

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  • (LWJGL) Pixel Unpack Buffer Object is Disabled? (glTextImage2D)

    - by OstlerDev
    I am trying to create a render target for my game so that I can re-render at a different screen size. But I am receiving the following error: Exception in thread "main" org.lwjgl.opengl.OpenGLException: Cannot use offsets when Pixel Unpack Buffer Object is disabled Here is the source code for my Render method: // clear screen GL11.glClear(GL11.GL_COLOR_BUFFER_BIT | GL11.GL_DEPTH_BUFFER_BIT); // Start FBO Rendering Code // The framebuffer, which regroups 0, 1, or more textures, and 0 or 1 depth buffer. int FramebufferName = GL30.glGenFramebuffers(); GL30.glBindFramebuffer(GL30.GL_FRAMEBUFFER, FramebufferName); // The texture we're going to render to int renderedTexture = glGenTextures(); // "Bind" the newly created texture : all future texture functions will modify this texture glBindTexture(GL_TEXTURE_2D, renderedTexture); // Give an empty image to OpenGL ( the last "0" ) glTexImage2D(GL_TEXTURE_2D, 0,GL_RGB, 1024, 768, 0,GL_RGB, GL_UNSIGNED_BYTE, 0); // Poor filtering. Needed ! glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); // Set "renderedTexture" as our colour attachement #0 GL32.glFramebufferTexture(GL30.GL_FRAMEBUFFER, GL30.GL_COLOR_ATTACHMENT0, renderedTexture, 0); // Set the list of draw buffers. IntBuffer drawBuffer = BufferUtils.createIntBuffer(20 * 20); GL20.glDrawBuffers(drawBuffer); // Always check that our framebuffer is ok if(GL30.glCheckFramebufferStatus(GL30.GL_FRAMEBUFFER) != GL30.GL_FRAMEBUFFER_COMPLETE){ System.out.println("Framebuffer was not created successfully! Exiting!"); return; } // Resets the current viewport GL11.glViewport(0, 0, scaleWidth*scale, scaleHeight*scale); GL11.glMatrixMode(GL11.GL_MODELVIEW); GL11.glLoadIdentity(); // let subsystem paint if (callback != null) { callback.frameRendering(); } // update window contents Display.update(); It is crashing on this line: glTexImage2D(GL_TEXTURE_2D, 0,GL_RGB, 1024, 768, 0,GL_RGB, GL_UNSIGNED_BYTE, 0); I am not really sure why it is crashing and looking around I have not been able to find out why. Any help or insight would be greatly welcome.

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  • 3D rotation matrices deform object while rotating

    - by Kevin
    I'm writing a small 3D renderer (using an orthographic projection right now). I've run into some trouble with my 3D rotation matrices. They seem to squeeze my 3D object (a box primitive) at certain angles. Here's a live demo (only tested in Google Chrome): http://dl.dropbox.com/u/109400107/3D/index.html The box is viewed from the top along the Y axis and is rotating around the X and Z axis. These are my 3 rotation matrices (Only rX and rZ are being used): var rX = new Matrix([ [1, 0, 0], [0, Math.cos(radiants), -Math.sin(radiants)], [0, Math.sin(radiants), Math.cos(radiants)] ]); var rY = new Matrix([ [Math.cos(radiants), 0, Math.sin(radiants)], [0, 1, 0], [-Math.sin(radiants), 0, Math.cos(radiants)] ]); var rZ = new Matrix([ [Math.cos(radiants), -Math.sin(radiants), 0], [Math.sin(radiants), Math.cos(radiants), 0], [0, 0, 1] ]); Before projecting the verticies I multiply them by rZ and rX like so: vert1.multiply(rZ); vert1.multiply(rX); vert2.multiply(rZ); vert2.multiply(rX); vert3.multiply(rZ); vert3.multiply(rX); The projection itself looks like this: bX = (pos.x + (vert1.x*scale)); bY = (pos.y + (vert1.z*scale)); Where "pos.x" and "pos.y" is an offset for centering the box on the screen. I just can't seem to find a solution to this and I'm still relativly new to working with Matricies. You can view the source-code of the demo page if you want to see the whole thing.

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  • Java's Object.wait method with nanoseconds: Is this a joke or am I missing something

    - by Krumia
    I was checking out the Java API source code (Java 8) just out of curiosity. And I found this in java/lang/Object.java. There are three methods named wait: public final native void wait(long timeout): This is the core of all wait methods, which has a native implementation. public final void wait(): Just calls wait(0). And then there is public final void wait(long timeout, int nanos). The JavaDoc for the particular method tells me that, This method is similar to the wait method of one argument, but it allows finer control over the amount of time to wait for a notification before giving up. The amount of real time, measured in nanoseconds, is given by: 1000000*timeout+nanos But this is how the methods achieves "finer control over the amount of time to wait": if (nanos >= 500000 || (nanos != 0 && timeout == 0)) { timeout++; } wait(timeout); So this method basically does a crude rounding up of nanoseconds to milliseconds. Not to mention that anything below 500000ns/0.5ms will be ignored. Is this piece of code bad/unnecessary code, or am I missing some unseen virtue of declaring this method, and it's no argument cousin as the way they are?

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  • XNA - 2D Rotation of an object to a selected direction

    - by lobsterhat
    I'm trying to figure out the best way of rotating an object towards the directional input of the user. I'm attempting to mimic making turns on ice skates. For instance, if the player is moving right and the input is down and left, the player should start rotating to the right a set amount each tick. I'll calculate a new vector based on current velocity and rotation and apply that to the current velocity. That should give me nice arcing turns, correct? At the moment I've got eight if/else statements for each key combination which in turn check the current rotation: // Rotate to 225 if (keyboardState.IsKeyDown(Keys.Up) && keyboardState.IsKeyDown(Keys.Left)) { // Rotate right if (rotation >= 45 || rotation < 225) { rotation += ROTATION_PER_TICK; } // Rotate left else if (rotation < 45 || rotation > 225) { rotation -= ROTATION_PER_TICK; } } This seems like a sloppy way to do this and eventually, I'll need to do this check about 10 times a tick. Any help toward a more efficient solution is appreciated.

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  • CSOM (Client Side Object Model) - What's new with SharePoint 2013

    - by KunaalKapoor
    SharePoint CSOMThe Client-Side Object Model or CSOM came out with SharePoint 2010. CSOM is accessible through client.svc but all client.svc calls must go through supported WFC entry points (supported entry points are .NET, Silverlight and JavaScript). So a developer would need to use client side proxy objects exposed by either a .NET assembly or a JavaScript library. Changes with SharePoint 2013REST Capabilities - Direct access to client.svcNew APIs - App ModelREST CapabilitiesOne of the most important changes to the CSOM with SharePoint 2013 is that the web service entry point of client.svc has been extended to allow direct access  via REST-Based web service calls. This is a really critical change since its going to make the SharePoint platform accessible to any other platform, opening the horizons of integration and collaboration with other REST based platforms and devices. OData (a really popular standard data access API for HTTP-based clients) is supported similar to 2010 but will be a more important aspect of SharePoint 2013 development.New API'sCSOM for SharePoint 2013 has been buffed up with several new APIs for not only SharePoint server functionality but also an API for Windows Phone applications. For a SharePoint 2010 farm most of the new APIs mentioned below are available only via server side APIs:SearchTaxonomyPublishingWorkflowUser ProfilesE-DiscoveryAnalyticsBusiness DataIRMFeedsSharePoint 2013 remote APIs being accessible through both CSOM and REST is very important to the new app model where developers can no longer run code in a SharePoint environment nor can they access the server-side APIs. So CSOM plays the savior here.Also, you can now substitute the alias '_api' in order to reference '_vti_bin/client.svc'.

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  • Moving an object using its velocity on a closed curve

    - by Futaro
    I want that an object follows a path, in Peggle game there are some pegs that have movement in a closed path. How can i get the same result? I guess that I can use parametric curve but I need use the velocity and not the position (x, y). I use NAPE and I have this in my gameloop: //circunference angle = angle + 1*(Math.PI / 180); movableBall.position.x = radius * Math.cos(angle)+ h; movableBall.position.y = radius * Math.sin(angle)+ k; it's works but I can not control the velocity, each movableBall must have its own velocity. Besides, from docs of NAPE:"Setting the position of a body is equivalent to simply teleporting the body; for instance moving a kinematic body by position is not the way to go about things.." I want to use: movableBall.velocity.x =?? movableBall.velocity.y = ?? The final idea is to follow others paths like the Lemniscate of Bernoulli. Thanks!

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  • Translating an object along its heading

    - by Kuros
    I am working on a simulation that requires me to have several objects moving around in 3D space (text output of their current position on the grid and heading is fine, I do not need graphics), and I am having some trouble getting objects to move along their relative headings. I have a basic understanding of vectors and matrices. I am using a vector to represent their position, and I am also using Euler Angles. I can translate one of my entities with a matrix along whatever axis, and I can alter their heading. For example, if I have an entity at (order is XYZ) 1, 1, 1, with a heading of 0, I can apply a translation matrix to get them to talk to 1, 1, 2 fine. However, if I change their heading to 270, they still walk to 1, 1, 3, instead of 2, 1, 2 as I desire. I have a feeling that my problem lies in not translating my matrix from world space to object space, but I am not sure how to go about that. How can I do this? Addition: I am using 3D vectors to represent their current position and their heading (using the three euler angles). For now, all I want to do is have an entity walk in a square, reporting their current position at each step. So, assuming it starts at 10, 10, 10 I want it to walk as follows: 10,10,10 -> 10, 10, 15 10, 10, 15 -> 5, 10, 15 5, 10, 15 -> 5, 10, 10 5, 10, 10 -> 10, 10, 10 My 1 Z unit translation matrix is as follows: [1 0 0 0] [0 1 0 0] [0 0 1 1] [0 0 0 1] My rotation matrix is as follows: [0 0 1 0] [0 1 0 0] [-1 0 0 0] [0 0 0 1]

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  • Getting Center and Radius of Irregural Object

    - by Moaz ELdeen
    I have drawn an asteroid object manually , and would like to get its center/radius by a specific equation. I think I can get them by calculated and hard-coded values. The code to draw the asteroid: void Asteroid::Draw() { float ratio = app::getWindowWidth()/app::getWindowHeight(); gl::pushMatrices(); gl::translate(m_Pos*ratio); gl::scale(3.5*ratio,3.5*ratio,3.5*ratio); gl::color(ci::Color(1,1,1)); gl::drawLine(Vec2f(-15,0),Vec2f(-10,-5)); gl::drawLine(Vec2f(-10,-5),Vec2f(-5,-5)); gl::drawLine(Vec2f(-5,-5),Vec2f(-5,-8)); gl::drawLine(Vec2f(-5,-8),Vec2f(5,-8)); gl::drawLine(Vec2f(5,-8),Vec2f(5,-5)); gl::drawLine(Vec2f(5,-5),Vec2f(10,-5)); gl::drawLine(Vec2f(10,-5),Vec2f(15,0)); gl::drawLine(Vec2f(15,0),Vec2f(10,5)); gl::drawLine(Vec2f(10,5),Vec2f(-10,5)); gl::drawLine(Vec2f(-10,5),Vec2f(-10,5)); gl::drawLine(Vec2f(-15,0),Vec2f(-10,5)); gl::popMatrices(); } According to the answer I have written that code to calculate the radius, is it correct or not ? cinder::Vec2f Asteroid::getCenter() { return ci::Vec2f(m_Pos.x, m_Pos.y); } double Asteroid::getRadius() { ci::Vec2f _vec = (getCenter()- Vec2f(15,5)); return _vec.length()*0.3f; }

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  • Sys.WebForms.PageRequestManagerServerErrorException: An entity object cannot be referenced by multiple instances of IEntityChangeTracker [closed]

    - by Mingebag
    `Story: I have a strange error when I try to save something I got this error message An entity object cannot be referenced by multiple instances of IEntityChangeTracker. I really don’t know what that is and why is it appear, it appears only when I try to save something my insert and update is working, only when I try to save something in db from my Telerik grid if (this.annualVacationList != null) { List<AnnualVacation> vacationToSave = this.annualVacationList; IEnumerable<AnnualVacation> existing = paramUser.AnnualVacations; foreach (AnnualVacation toSave in vacationToSave) { AnnualVacation existingItem = existing.Where(x => x.AnnualVacationId == toSave.AnnualVacationId).SingleOrDefault(); if (existingItem == null) { ctx.AddToAnnualVacations(toSave); } else { existingItem.FromDate = toSave.FromDate; existingItem.ToDate = toSave.ToDate; existingItem.WorkingTime = toSave.WorkingTime; existingItem.VacationDays = toSave.VacationDays; } } } ctx.SaveChanges(); } After debugging I have seen that the code brake down in the Project.Name.Designer.cs ..... O.o public void AddToAnnualVacations(AnnualVacation annualVacation) { base.AddObject("AnnualVacations", annualVacation); }

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  • Dynamic object creation with HashMap

    - by Salor
    I want to use a HashMap to dynamically create objects based on the key. I have a Random Map Generator that stores the maps in 3D Arrays of Type Integer[][][]. Upon creation of the actual map I iterate through this array and based on the Integer I want to create the right block. Example: Integer[][][] map ... map[6][6][6] = 3; 3 is a Earth-Block and now I want to initialize a new Block of this type and give it the right coordinates. Currently I store my Bindings from Integer to Class in a HashMap(Integer, String) and create my objects like that: int id = array[x][y][z]; String block_name = Blocks.map.get(id); Block block = (Block) Class.forName(block_name).newInstance(); block.setPosition(x,y,z); But I want to avoid newInstance() if possible. I've never worked that dynamically with Java before and I couldn't find a solution like changing the HashMap to (Integer, Class) or something. I just need to create a new Object based upon the Integer. Any ideas/solutions? Thanks in advance and have a wonderful day!

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  • Large Object Heap Fragmentation

    - by Paul Ruane
    The C#/.NET application I am working on is suffering from a slow memory leak. I have used CDB with SOS to try to determine what is happening but the data does not seem to make any sense so I was hoping one of you may have experienced this before. The application is running on the 64 bit framework. It is continuously calculating and serialising data to a remote host and is hitting the Large Object Heap (LOH) a fair bit. However, most of the LOH objects I expect to be transient: once the calculation is complete and has been sent to the remote host, the memory should be freed. What I am seeing, however, is a large number of (live) object arrays interleaved with free blocks of memory, e.g., taking a random segment from the LOH: 0:000> !DumpHeap 000000005b5b1000 000000006351da10 Address MT Size ... 000000005d4f92e0 0000064280c7c970 16147872 000000005e45f880 00000000001661d0 1901752 Free 000000005e62fd38 00000642788d8ba8 1056 <-- 000000005e630158 00000000001661d0 5988848 Free 000000005ebe6348 00000642788d8ba8 1056 000000005ebe6768 00000000001661d0 6481336 Free 000000005f214d20 00000642788d8ba8 1056 000000005f215140 00000000001661d0 7346016 Free 000000005f9168a0 00000642788d8ba8 1056 000000005f916cc0 00000000001661d0 7611648 Free 00000000600591c0 00000642788d8ba8 1056 00000000600595e0 00000000001661d0 264808 Free ... Obviously I would expect this to be the case if my application were creating long-lived, large objects during each calculation. (It does do this and I accept there will be a degree of LOH fragmentation but that is not the problem here.) The problem is the very small (1056 byte) object arrays you can see in the above dump which I cannot see in code being created and which are remaining rooted somehow. Also note that CDB is not reporting the type when the heap segment is dumped: I am not sure if this is related or not. If I dump the marked (<--) object, CDB/SOS reports it fine: 0:015> !DumpObj 000000005e62fd38 Name: System.Object[] MethodTable: 00000642788d8ba8 EEClass: 00000642789d7660 Size: 1056(0x420) bytes Array: Rank 1, Number of elements 128, Type CLASS Element Type: System.Object Fields: None The elements of the object array are all strings and the strings are recognisable as from our application code. Also, I am unable to find their GC roots as the !GCRoot command hangs and never comes back (I have even tried leaving it overnight). So, I would very much appreciate it if anyone could shed any light as to why these small (<85k) object arrays are ending up on the LOH: what situations will .NET put a small object array in there? Also, does anyone happen to know of an alternative way of ascertaining the roots of these objects? Thanks in advance. Update 1 Another theory I came up with late yesterday is that these object arrays started out large but have been shrunk leaving the blocks of free memory that are evident in the memory dumps. What makes me suspicious is that the object arrays always appear to be 1056 bytes long (128 elements), 128 * 8 for the references and 32 bytes of overhead. The idea is that perhaps some unsafe code in a library or in the CLR is corrupting the number of elements field in the array header. Bit of a long shot I know... Update 2 Thanks to Brian Rasmussen (see accepted answer) the problem has been identified as fragmentation of the LOH caused by the string intern table! I wrote a quick test application to confirm this: static void Main() { const int ITERATIONS = 100000; for (int index = 0; index < ITERATIONS; ++index) { string str = "NonInterned" + index; Console.Out.WriteLine(str); } Console.Out.WriteLine("Continue."); Console.In.ReadLine(); for (int index = 0; index < ITERATIONS; ++index) { string str = string.Intern("Interned" + index); Console.Out.WriteLine(str); } Console.Out.WriteLine("Continue?"); Console.In.ReadLine(); } The application first creates and dereferences unique strings in a loop. This is just to prove that the memory does not leak in this scenario. Obviously it should not and it does not. In the second loop, unique strings are created and interned. This action roots them in the intern table. What I did not realise is how the intern table is represented. It appears it consists of a set of pages -- object arrays of 128 string elements -- that are created in the LOH. This is more evident in CDB/SOS: 0:000> .loadby sos mscorwks 0:000> !EEHeap -gc Number of GC Heaps: 1 generation 0 starts at 0x00f7a9b0 generation 1 starts at 0x00e79c3c generation 2 starts at 0x00b21000 ephemeral segment allocation context: none segment begin allocated size 00b20000 00b21000 010029bc 0x004e19bc(5118396) Large object heap starts at 0x01b21000 segment begin allocated size 01b20000 01b21000 01b8ade0 0x00069de0(433632) Total Size 0x54b79c(5552028) ------------------------------ GC Heap Size 0x54b79c(5552028) Taking a dump of the LOH segment reveals the pattern I saw in the leaking application: 0:000> !DumpHeap 01b21000 01b8ade0 ... 01b8a120 793040bc 528 01b8a330 00175e88 16 Free 01b8a340 793040bc 528 01b8a550 00175e88 16 Free 01b8a560 793040bc 528 01b8a770 00175e88 16 Free 01b8a780 793040bc 528 01b8a990 00175e88 16 Free 01b8a9a0 793040bc 528 01b8abb0 00175e88 16 Free 01b8abc0 793040bc 528 01b8add0 00175e88 16 Free total 1568 objects Statistics: MT Count TotalSize Class Name 00175e88 784 12544 Free 793040bc 784 421088 System.Object[] Total 1568 objects Note that the object array size is 528 (rather than 1056) because my workstation is 32 bit and the application server is 64 bit. The object arrays are still 128 elements long. So the moral to this story is to be very careful interning. If the string you are interning is not known to be a member of a finite set then your application will leak due to fragmentation of the LOH, at least in version 2 of the CLR. In our application's case, there is general code in the deserialisation code path that interns entity identifiers during unmarshalling: I now strongly suspect this is the culprit. However, the developer's intentions were obviously good as they wanted to make sure that if the same entity is deserialised multiple times then only one instance of the identifier string will be maintained in memory.

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  • Building big, immutable objects without constructors having long parameter lists

    - by Malax
    Hi StackOverflow! I have some big (more than 3 fields) Objects which can and should be immutable. Every time I run into that case i tend to create constructor abominations with long parameter lists. It doesn't feel right, is hard to use and readability suffers. It is even worse if the fields are some sort of collection type like lists. A simple addSibling(S s) would ease the object creation so much but renders the object mutable. What do you guys use in such cases? I'm on Scala and Java, but i think the problem is language agnostic as long as the language is object oriented. Solutions I can think of: "Constructor abominations with long parameter lists" The Builder Pattern Thanks for your input!

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  • Building big, immutable objects without using constructors having long parameter lists

    - by Malax
    Hi StackOverflow! I have some big (more than 3 fields) Objects which can and should be immutable. Every time I run into that case i tend to create constructor abominations with long parameter lists. It doesn't feel right, is hard to use and readability suffers. It is even worse if the fields are some sort of collection type like lists. A simple addSibling(S s) would ease the object creation so much but renders the object mutable. What do you guys use in such cases? I'm on Scala and Java, but i think the problem is language agnostic as long as the language is object oriented. Solutions I can think of: "Constructor abominations with long parameter lists" The Builder Pattern Thanks for your input!

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  • Locking on an object...

    - by Mystere Man
    I often see code like that which is shown here, ie where an object is allocated and then used as a "lock object". It seems to me that you could use any object for this, including the event itself as the lock object. Why allocate a new object that does nothing? My understanding is that calling lock() on an object doesn't actually alter the object itself, nor does it actually lock it from being used, it's simply used as a placeholder for multiple lock statements to anchor on. So my question is, is this really a good thing to do?

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  • Have you been stuck with the math in a Flash project?

    - by VideoDnd
    Have you been stuck with the math in a Flash project? It's a loose design pattern my director formulated. My goal is to keep the project object oriented, and get 'non Flash obstacles' off my plate. XML values going to AS3, updating a changing acceleration formula. I don't hate math, but it just doesn't seem OOP or good project planning to have the math stuck in Flash. Your comments are welcome.

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  • Learning to write organized and modular programs

    - by Peter
    I'm a computer science student, and I'm just starting to write relatively larger programs for my coursework (between 750 - 1500 lines). Up until now, it's been possible to get by with any reasonable level of modularization and object oriented design. However, now that I'm writing more complex code for my assignments I'd like to learn to write better code. Can anyone point me in the direction of some resources for learning about what sort of things to look for when designing your program's architecture so that you can make it as modularized as possible?

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  • Does Scheme work with Microsoft COM?

    - by Martin
    I'm new to Scheme -- the functional programming language and I like it a lot for its first-class/higher-order functions. However, my data comes from a COM source with an object-oriented API. I know Scheme and COM belong to different programming paradigms, but I'm wondering if there is any interface or a way for Scheme to connect to a COM source? Thanks.

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