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  • java.lang.OutOfMemoryError: bitmap size exceeds VM budget

    - by Angel
    Hi, I am trying to change the layout of my application from portrait to landscape and vice-versa. But if i do it frequently or more than once then at times my application crashes.. Below is the error log. Please suggest what can be done? < 01-06 09:52:27.787: ERROR/dalvikvm-heap(17473): 1550532-byte external allocation too large for this process. 01-06 09:52:27.787: ERROR/dalvikvm(17473): Out of memory: Heap Size=6471KB, Allocated=4075KB, Bitmap Size=9564KB 01-06 09:52:27.787: ERROR/(17473): VM won't let us allocate 1550532 bytes 01-06 09:52:27.798: DEBUG/skia(17473): --- decoder-decode returned false 01-06 09:52:27.798: DEBUG/AndroidRuntime(17473): Shutting down VM 01-06 09:52:27.798: WARN/dalvikvm(17473): threadid=3: thread exiting with uncaught exception (group=0x4001e390) 01-06 09:52:27.807: ERROR/AndroidRuntime(17473): Uncaught handler: thread main exiting due to uncaught exception 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): java.lang.RuntimeException: Unable to start activity ComponentInfo{}: android.view.InflateException: Binary XML file line #2: Error inflating class 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2596) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2621) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3812) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.app.ActivityThread.access$2300(ActivityThread.java:126) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1936) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.os.Handler.dispatchMessage(Handler.java:99) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.os.Looper.loop(Looper.java:123) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.app.ActivityThread.main(ActivityThread.java:4595) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at java.lang.reflect.Method.invokeNative(Native Method) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at java.lang.reflect.Method.invoke(Method.java:521) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at dalvik.system.NativeStart.main(Native Method) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): Caused by: android.view.InflateException: Binary XML file line #2: Error inflating class 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.view.LayoutInflater.createView(LayoutInflater.java:513) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:56) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:563) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.view.LayoutInflater.inflate(LayoutInflater.java:385) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.view.LayoutInflater.inflate(LayoutInflater.java:320) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.view.LayoutInflater.inflate(LayoutInflater.java:276) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:207) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.app.Activity.setContentView(Activity.java:1629) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at onCreate(Game.java:98) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2544) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): ... 12 more 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): Caused by: java.lang.reflect.InvocationTargetException 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.widget.LinearLayout.(LinearLayout.java:92) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at java.lang.reflect.Constructor.constructNative(Native Method) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at java.lang.reflect.Constructor.newInstance(Constructor.java:446) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.view.LayoutInflater.createView(LayoutInflater.java:500) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): ... 22 more 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): Caused by: java.lang.OutOfMemoryError: bitmap size exceeds VM budget 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.graphics.BitmapFactory.nativeDecodeAsset(Native Method) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:464) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.graphics.BitmapFactory.decodeResourceStream(BitmapFactory.java:340) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.graphics.drawable.Drawable.createFromResourceStream(Drawable.java:697) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.content.res.Resources.loadDrawable(Resources.java:1705) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.content.res.TypedArray.getDrawable(TypedArray.java:548) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.view.View.(View.java:1850) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.view.View.(View.java:1799) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): at android.view.ViewGroup.(ViewGroup.java:296) 01-06 09:52:27.857: ERROR/AndroidRuntime(17473): ... 26 more

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  • Why aren't arrays expandable?

    - by Mustafa
    When we create an array, we cannot change its size; it's fixed. OK, seems nice, we can create a new bigger array and copy the values one by one and that's little slow. What's the technical background of it?

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  • Feedback on Optimizing C# NET Code Block

    - by Brett Powell
    I just spent quite a few hours reading up on TCP servers and my desired protocol I was trying to implement, and finally got everything working great. I noticed the code looks like absolute bollocks (is the the correct usage? Im not a brit) and would like some feedback on optimizing it, mostly for reuse and readability. The packet formats are always int, int, int, string, string. try { BinaryReader reader = new BinaryReader(clientStream); int packetsize = reader.ReadInt32(); int requestid = reader.ReadInt32(); int serverdata = reader.ReadInt32(); Console.WriteLine("Packet Size: {0} RequestID: {1} ServerData: {2}", packetsize, requestid, serverdata); List<byte> str = new List<byte>(); byte nextByte = reader.ReadByte(); while (nextByte != 0) { str.Add(nextByte); nextByte = reader.ReadByte(); } // Password Sent to be Authenticated string string1 = Encoding.UTF8.GetString(str.ToArray()); str.Clear(); nextByte = reader.ReadByte(); while (nextByte != 0) { str.Add(nextByte); nextByte = reader.ReadByte(); } // NULL string string string2 = Encoding.UTF8.GetString(str.ToArray()); Console.WriteLine("String1: {0} String2: {1}", string1, string2); // Reply to Authentication Request MemoryStream stream = new MemoryStream(); BinaryWriter writer = new BinaryWriter(stream); writer.Write((int)(1)); // Packet Size writer.Write((int)(requestid)); // Mirror RequestID if Authenticated, -1 if Failed byte[] buffer = stream.ToArray(); clientStream.Write(buffer, 0, buffer.Length); clientStream.Flush(); } I am going to be dealing with other packet types as well that are formatted the same (int/int/int/str/str), but different values. I could probably create a packet class, but this is a bit outside my scope of knowledge for how to apply it to this scenario. If it makes any difference, this is the Protocol I am implementing. http://developer.valvesoftware.com/wiki/Source_RCON_Protocol

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  • Windows XP GUI programming language

    - by bobir
    I need to write a Windows XP/Vista application, main requirements: Just one .exe file, without extra runtime, like Air, .Net; posstibly a couple of dlls. Very small file size. The application is for network centric usage, similar to ICQ or Gtalk clients. Thanks in advance.

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  • Initializing a C++ vector to random values... fast

    - by Flamewires
    Hey, id like to make this as fast as possible because it gets called A LOT in a program i'm writing, so is there any faster way to initialize a C++ vector to random values than: double range;//set to the range of a particular function i want to evaluate. std::vector<double> x(30, 0.0); for (int i=0;i<x.size();i++) { x.at(i) = (rand()/(double)RAND_MAX)*range; } EDIT:Fixed x's initializer.

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  • .NET GDI+ image size - file codec limitations

    - by roygbiv
    Is there a limit on the size of image that can be encoded using the image file codecs available from .NET? I'm trying to encode images 4GB in size, but it simply does not work (or does not work properly i.e. writes out an unreadable file) with .bmp, .jpg, .png or the .tif encoders. When I lower the image size to < 2GB it does work with the .jpg but not the .bmp, .tif or .png. My next attempt would be to try libtiff because I know tiff files are meant for large images. What is a good file format for large images? or am I just hitting the file format limitations? Random r = new Random((int)DateTime.Now.Ticks); int width = 64000; int height = 64000; int stride = (width % 4) > 0 ? width + (width % 4) : width; UIntPtr dataSize = new UIntPtr((ulong)stride * (ulong)height); IntPtr p = Program.VirtualAlloc(IntPtr.Zero, dataSize, Program.AllocationType.COMMIT | Program.AllocationType.RESERVE, Program.MemoryProtection.READWRITE); Bitmap bmp = new Bitmap(width, height, stride, PixelFormat.Format8bppIndexed, p); BitmapData bd = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.ReadWrite, bmp.PixelFormat); ColorPalette cp = bmp.Palette; for (int i = 0; i < cp.Entries.Length; i++) { cp.Entries[i] = Color.FromArgb(i, i, i); } bmp.Palette = cp; unsafe { for (int y = 0; y < bd.Height; y++) { byte* row = (byte*)bd.Scan0.ToPointer() + (y * bd.Stride); for (int x = 0; x < bd.Width; x++) { *(row + x) = (byte)r.Next(256); } } } bmp.UnlockBits(bd); bmp.Save(@"c:\test.jpg", ImageFormat.Jpeg); bmp.Dispose(); Program.VirtualFree(p, UIntPtr.Zero, 0x8000); I have also tried using a pinned GC memory region, but this is limited to < 2GB. Random r = new Random((int)DateTime.Now.Ticks); int bytesPerPixel = 4; int width = 4000; int height = 4000; int padding = 4 - ((width * bytesPerPixel) % 4); padding = (padding == 4 ? 0 : padding); int stride = (width * bytesPerPixel) + padding; UInt32[] pixels = new UInt32[width * height]; GCHandle gchPixels = GCHandle.Alloc(pixels, GCHandleType.Pinned); using (Bitmap bmp = new Bitmap(width, height, stride, PixelFormat.Format32bppPArgb, gchPixels.AddrOfPinnedObject())) { for (int y = 0; y < height; y++) { int row = (y * width); for (int x = 0; x < width; x++) { pixels[row + x] = (uint)r.Next(); } } bmp.Save(@"c:\test.jpg", ImageFormat.Jpeg); } gchPixels.Free();

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  • Flexible array members in C - bad?

    - by Lionel
    I recently read that using flexible array members in C was poor software engineering practice. However, that statement was not backed by any argument. Is this an accepted fact? (Flexible array members are a C feature introduced in C99 whereby one can declare the last element to be an array of unspecified size. For example: ) struct header { size_t len; unsigned char data[]; };

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  • faster implementation of sum ( for Codility test )

    - by Oscar Reyes
    How can the following simple implementation of sum be faster? private long sum( int [] a, int begin, int end ) { if( a == null ) { return 0; } long r = 0; for( int i = begin ; i < end ; i++ ) { r+= a[i]; } return r; } EDIT Background is in order. Reading latest entry on coding horror, I came to this site: http://codility.com which has this interesting programming test. Anyway, I got 60 out of 100 in my submission, and basically ( I think ) is because this implementation of sum, because those parts where I failed are the performance parts. I'm getting TIME_OUT_ERROR's So, I was wondering if an optimization in the algorithm is possible. So, no built in functions or assembly would be allowed. This my be done in C, C++, C#, Java or pretty much in any other. EDIT As usual, mmyers was right. I did profile the code and I saw most of the time was spent on that function, but I didn't understand why. So what I did was to throw away my implementation and start with a new one. This time I've got an optimal solution [ according to San Jacinto O(n) -see comments to MSN below - ] This time I've got 81% on Codility which I think is good enough. The problem is that I didn't take the 30 mins. but around 2 hrs. but I guess that leaves me still as a good programmer, for I could work on the problem until I found an optimal solution: Here's my result. I never understood what is those "combinations of..." nor how to test "extreme_first"

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  • How can i optimize this c# code?

    - by Pandiya Chendur
    I have converted my Datatable to json string use the following method... public string GetJSONString(DataTable Dt) { string[] StrDc = new string[Dt.Columns.Count]; string HeadStr = string.Empty; for (int i = 0; i < Dt.Columns.Count; i++) { StrDc[i] = Dt.Columns[i].Caption; HeadStr += "\"" + StrDc[i] + "\" : \"" + StrDc[i] + i.ToString() + "¾" + "\","; } HeadStr = HeadStr.Substring(0, HeadStr.Length - 1); StringBuilder Sb = new StringBuilder(); Sb.Append("{\"" + Dt.TableName + "\" : ["); for (int i = 0; i < Dt.Rows.Count; i++) { string TempStr = HeadStr; Sb.Append("{"); for (int j = 0; j < Dt.Columns.Count; j++) { if (Dt.Rows[i][j].ToString().Contains("'") == true) { Dt.Rows[i][j] = Dt.Rows[i][j].ToString().Replace("'", ""); } TempStr = TempStr.Replace(Dt.Columns[j] + j.ToString() + "¾", Dt.Rows[i][j].ToString()); } Sb.Append(TempStr + "},"); } Sb = new StringBuilder(Sb.ToString().Substring(0, Sb.ToString().Length - 1)); Sb.Append("]}"); return Sb.ToString(); } Is this fair enough or still there is margin for optimization to make it execute faster.... Any suggestion...

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  • How to implement Excel Solver functionality in C#?

    - by Vic
    Hi, I have an application in C#, I need to do some optimization calculations, like Excel Solver Add-in does, one option is certainly to write my own solver implementation, but I'm kind of short of time, so I'm looking into libraries that already exist that can help me with this. I've been trying the Microsoft Solver Foundation, which seems pretty neat and cool, the problem is that it doesn't seem to work with the kind of calculations that I need to do. At the end of this question I'm adding the information about the calculations I need to perform and optimize. So basically my question is if any of you know of any other library that I can use for this purpose, or any tutorial that can help to do my own solver, or any idea that gives me a lead to solve this issue. Thanks. Additional Info: This is the data I need to calculate: I have 7 variables, lets call them var1, var2,...,var7 The constraints for these variables are: All of them need to be 0 <= varn <= 0.5 (where n is the number of the variable) The sum of all the variables should be equal to 1 The objective is to maximize the target formula, which in Excel looks like this: (MMULT(TRANSPOSE(L26:L32),M14:M20)) / (SQRT(MMULT(MMULT(TRANSPOSE(L26:L32),M4:S10),L26:L32))) The range that you see in this formula, L26:L32, is actually the range with the variables from above, var1, var2,..., varn. M14:M20 and M4:S10 are ranges with data that I get from different sources, there are more likely decimal values. As I said before, I was using Microsoft Solver Foundation, I modeled pretty much everything with it, I created functions that handle the operations of the target formula, but when I tried to solve the model it always fail, I think it is because of the complexity of the operations. In any case, I just wanted to show these data so you can have an idea about the kind of calculations that I need to implement.

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  • Draw Rectangle with XNA

    - by mazzzzz
    Hey guys, I was working on game, and wanted to highlight a spot on the screen when something happens, I created a class to do this for me, and found a bit of code to draw the rectangle static private Texture2D CreateRectangle(int width, int height, Color colori) { Texture2D rectangleTexture = new Texture2D(game.GraphicsDevice, width, height, 1, TextureUsage.None, SurfaceFormat.Color);// create the rectangle texture, ,but it will have no color! lets fix that Color[] color = new Color[width * height];//set the color to the amount of pixels in the textures for (int i = 0; i < color.Length; i++)//loop through all the colors setting them to whatever values we want { color[i] = colori; } rectangleTexture.SetData(color);//set the color data on the texture return rectangleTexture;//return the texture } Problem is that the code above is called every update, (60 times a second), and it was not written with optimization in mind, I have no clue how else to write a code to do this though. It needs to be extremely fast (the code above freezes the game, which has only skeleton code right now).. Any suggestions. Note: Any new code would be great (WireFrame/Fill are both fine). I would like to be able to specify color. Something to point in the right direction would be great, Thanks, Max

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  • PHP Performance Metrics

    - by bigstylee
    I am currently developing a PHP MVC Framework for a personal project. While I am developing the framework I am interested to see any notable performance by implementing different techniques for optimization. I have implemented a crude BenchMark class that logs mircotime. The problem is I have no frame of reference for execution times. I am very near the beginnig of this project with a database connection and a few queries but no output (bar some debugging text and BenchMark log). I have a current execution time of 0.01917 seconds. I was expecting this to be lower but as I said before I have no frame of reference. I appreciate there are many variables to take into account when juding performance but I am hoping to find some sort of metric to a) techniques to measure performance for example requests per second and b) compare results for example; how a "moderately" sized PHP application on a "standard" webserver will perform. I appreciate "moderately" and "standard" are very subjective words so perhaps a table of known execution times for a particular application (eg StackOverFlow's executing time). What are other techniques of measuring performance are there other than execution time? When looking at MVC Framework Performance Comparisom it talks about Requests Per Second (RPS). How is this calculated? I am guessing with my current execution time of 0.01917 seconds can handle 52 RPS (= 1 / 0.01917 ). This seems to be significantly lower than that quoted on the graph especially when you consider my current limited funcitonality.

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  • Optimizing MySQL update query

    - by Jernej Jerin
    This is currently my MySQL UPDATE query, which is called from program written in Java: String query = "UPDATE maxday SET DatePressureREL = (SELECT Date FROM ws3600 WHERE PressureREL = (SELECT MAX" + "(PressureREL) FROM ws3600 WHERE Date >= '" + Date + "') AND Date >= '" + Date + "' ORDER BY Date DESC LIMIT 1), " + "PressureREL = (SELECT PressureREL FROM ws3600 WHERE PressureREL = (SELECT MAX(PressureREL) FROM ws3600 " + "WHERE Date >= '" + Date + "') AND Date >= '" + Date + "' ORDER BY Date DESC LIMIT 1), ..."; try { s.execute(query); } catch (SQLException e) { System.out.println("SQL error"); } catch(Exception e) { e.printStackTrace(); } Let me explain first, what does it do. I have two tables, first is ws3600, which holds columns (Date, PressureREL, TemperatureOUT, Dewpoint, ...). Then I have second table, called maxday, which holds columns like DatePressureREL, PressureREL, DateTemperatureOUT, TemperatureOUT,... Now as you can see from an example, I update each column, the question is, is there a faster way? I am asking this, because I am calling MAX twice, first to find the Date for that value and secondly to find the actual value. Now I know that I could write like that: SELECT Date, PressureREL FROM ws3600 WHERE PressureREL = (SELECT MAX(PressureREL) FROM ws3600 WHERE Date >= '" + Date + "') AND Date >= '" + Date + "' ORDER BY Date DESC LIMIT 1 That way I get the Date of the max and the max value at the same time and then update with those values the data in maxday table. But the problem of this solution is, that I have to execute many queries, which as I understand takes alot more time compared to executing one long mysql query because of overhead in sending each query to the server. If there is no better way, which solution beetwen this two should I choose. The first, which only takes one query but is very unoptimized or the second which is beter in terms of optimization, but needs alot more queries which probably means that the preformance gain is lost because of overhead in sending each query to the server?

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  • SQL: Speed Improvement - Cluttered union query

    - by vol7ron
    SELECT * FROM ( SELECT a.user_id, a.f_name, a.l_name, b.user_id, b.f_name, b.l_name FROM current_tbl a INNER JOIN import_tbl b ON ( a.user_id = b.user_id ) UNION SELECT a.user_id, a.f_name, a.l_name, b.user_id, b.f_name, b.l_name FROM current_tbl a INNER JOIN import_tbl b ON ( lower(a.f_name)=lower(b.f_name) AND lower(a.l_name)=lower(b.l_name) ) ) foo -- UNION -- SELECT a.user_id , a.f_name , a.l_name , '' , '' , '' FROM current_tbl a WHERE a.user_id NOT IN ( select user_id from( SELECT a.user_id, a.f_name, a.l_name, b.user_id, b.f_name, b.l_name FROM current_tbl a INNER JOIN import_tbl b ON ( a.user_id = b.user_id ) UNION SELECT a.user_id, a.f_name, a.l_name, b.user_id, b.f_name, b.l_name FROM current_tbl a INNER JOIN import_tbl b ON ( lower(a.f_name)=lower(b.f_name) AND lower(a.l_name)=lower(b.l_name) ) ) bar ) ORDER BY user_id Example of table population: current_tbl: ------------------------------- user_id | f_name | l_name ---------+----------+---------- A1 | Adam | Acorn A2 | Beth | Berry A3 | Calv | Chard | | import_tbl: ------------------------------- user_id | f_name | l_name ---------+----------+---------- A1 | Adam | Acorn A2 | Beth | Butcher <- last_name different | | Expected Output: ----------------------------------------------------------------------- user_id1 | f_name1 | l_name1 | user_id2 | f_name2 | l_name2 ----------+-----------+-----------+------------+-----------+----------- A1 | Adam | Acorn | A1 | Adam | Acorn A2 | Beth | Berry | A2 | Beth | Butcher A3 | Calv | Chard | | | Doing this method gets rid of conditions where the row would be: A2 | Beth | Berry | A2 | Beth | Butcher But it keeps the A3 row I hope this makes sense and I haven't overly simplified it. This is a continuation question from my other question. The succession of these improvements has dropped the query down from ~32000ms to where it's at now ~1200ms - quite an improvement. I supect I can optimize by using UNION ALL in the subquery and of course the usual index optimizations, but I'm looking for the best SQL optimization. FYI this particular case is for PostgreSQL.

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  • Compile and optimize for different target architectures

    - by Peter Smit
    Summary: I want to take advantage of compiler optimizations and processor instruction sets, but still have a portable application (running on different processors). Normally I could indeed compile 5 times and let the user choose the right one to run. My question is: how can I can automate this, so that the processor is detected at runtime and the right executable is executed without the user having to chose it? I have an application with a lot of low level math calculations. These calculations will typically run for a long time. I would like to take advantage of as much optimization as possible, preferably also of (not always supported) instruction sets. On the other hand I would like my application to be portable and easy to use (so I would not like to compile 5 different versions and let the user choose). Is there a possibility to compile 5 different versions of my code and run dynamically the most optimized version that's possible at execution time? With 5 different versions I mean with different instruction sets and different optimizations for processors. I don't care about the size of the application. At this moment I'm using gcc on Linux (my code is in C++), but I'm also interested in this for the Intel compiler and for the MinGW compiler for compilation to Windows. The executable doesn't have to be able to run on different OS'es, but ideally there would be something possible with automatically selecting 32 bit and 64 bit as well. Edit: Please give clear pointers how to do it, preferably with small code examples or links to explanations. From my point of view I need a super generic solution, which is applicable on any random C++ project I have later. Edit I assigned the bounty to ShuggyCoUk, he had a great number of pointers to look out for. I would have liked to split it between multiple answers but that is not possible. I'm not having this implemented yet, so the question is still 'open'! Please, still add and/or improve answers, even though there is no bounty to be given anymore. Thanks everybody!

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  • Algorithm for finding the best routes for food distribution in game

    - by Tautrimas
    Hello, I'm designing a city building game and got into a problem. Imagine Sierra's Caesar III game mechanics: you have many city districts with one market each. There are several granaries over the distance connected with a directed weighted graph. The difference: people (here cars) are units that form traffic jams (here goes the graph weights). Note: in Ceasar game series, people harvested food and stockpiled it in several big granaries, whereas many markets (small shops) took food from the granaries and delivered it to the citizens. The task: tell each district where they should be getting their food from while taking least time and minimizing congestions on the city's roads. Map example Sample diagram Suppose that yellow districts need 7, 7 and 4 apples accordingly. Bluish granaries have 7 and 11 apples accordingly. Suppose edges weights to be proportional to their length. Then, the solution should be something like the gray numbers indicated on the edges. Eg, first district gets 4 apples from the 1st and 3 apples from the 2nd granary, while the last district gets 4 apples from only the 2nd granary. Here, vertical roads are first occupied to the max, and then the remaining workers are sent to the diagonal paths. Question What practical and very fast algorithm should I use? I was looking at some papers (Congestion Games: Optimization in Competition etc.) describing congestion games, but could not get the big picture. Any help is very appreciated! P. S. I can post very little links and no images because of new user restriction.

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  • Coding Practices which enable the compiler/optimizer to make a faster program.

    - by EvilTeach
    Many years ago, C compilers were not particularly smart. As a workaround K&R invented the register keyword, to hint to the compiler, that maybe it would be a good idea to keep this variable in an internal register. They also made the tertiary operator to help generate better code. As time passed, the compilers matured. They became very smart in that their flow analysis allowing them to make better decisions about what values to hold in registers than you could possibly do. The register keyword became unimportant. FORTRAN can be faster than C for some sorts of operations, due to alias issues. In theory with careful coding, one can get around this restriction to enable the optimizer to generate faster code. What coding practices are available that may enable the compiler/optimizer to generate faster code? Identifying the platform and compiler you use, would be appreciated. Why does the technique seem to work? Sample code is encouraged. Here is a related question [Edit] This question is not about the overall process to profile, and optimize. Assume that the program has been written correctly, compiled with full optimization, tested and put into production. There may be constructs in your code that prohibit the optimizer from doing the best job that it can. What can you do to refactor that will remove these prohibitions, and allow the optimizer to generate even faster code? [Edit] Offset related link

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  • Improving File Read Performance (single file, C++, Windows)

    - by david
    I have large (hundreds of MB or more) files that I need to read blocks from using C++ on Windows. Currently the relevant functions are: errorType LargeFile::read( void* data_out, __int64 start_position, __int64 size_bytes ) const { if( !m_open ) { // return error } else { seekPosition( start_position ); DWORD bytes_read; BOOL result = ReadFile( m_file, data_out, DWORD( size_bytes ), &bytes_read, NULL ); if( size_bytes != bytes_read || result != TRUE ) { // return error } } // return no error } void LargeFile::seekPosition( __int64 position ) const { LARGE_INTEGER target; target.QuadPart = LONGLONG( position ); SetFilePointerEx( m_file, target, NULL, FILE_BEGIN ); } The performance of the above does not seem to be very good. Reads are on 4K blocks of the file. Some reads are coherent, most are not. A couple questions: Is there a good way to profile the reads? What things might improve the performance? For example, would sector-aligning the data be useful? I'm relatively new to file i/o optimization, so suggestions or pointers to articles/tutorials would be helpful.

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  • Efficient way to maintain a sorted list of access counts in Python

    - by David
    Let's say I have a list of objects. (All together now: "I have a list of objects.") In the web application I'm writing, each time a request comes in, I pick out up to one of these objects according to unspecified criteria and use it to handle the request. Basically like this: def handle_request(req): for h in handlers: if h.handles(req): return h return None Assuming the order of the objects in the list is unimportant, I can cut down on unnecessary iterations by keeping the list sorted such that the most frequently used (or perhaps most recently used) objects are at the front. I know this isn't something to be concerned about - it'll make only a miniscule, undetectable difference in the app's execution time - but debugging the rest of the code is driving me crazy and I need a distraction :) so I'm asking out of curiosity: what is the most efficient way to maintain the list in sorted order, descending, by the number of times each handler is chosen? The obvious solution is to make handlers a list of (count, handler) pairs, and each time a handler is chosen, increment the count and resort the list. def handle_request(req): for h in handlers[:]: if h[1].handles(req): h[0] += 1 handlers.sort(reverse=True) return h[1] return None But since there's only ever going to be at most one element out of order, and I know which one it is, it seems like some sort of optimization should be possible. Is there something in the standard library, perhaps, that is especially well-suited to this task? Or some other data structure? (Even if it's not implemented in Python) Or should/could I be doing something completely different?

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  • optimize output value using a class and public member

    - by wiso
    Suppose you have a function, and you call it a lot of times, every time the function return a big object. I've optimized the problem using a functor that return void, and store the returning value in a public member: #include <vector> const int N = 100; std::vector<double> fun(const std::vector<double> & v, const int n) { std::vector<double> output = v; output[n] *= output[n]; return output; } class F { public: F() : output(N) {}; std::vector<double> output; void operator()(const std::vector<double> & v, const int n) { output = v; output[n] *= n; } }; int main() { std::vector<double> start(N,10.); std::vector<double> end(N); double a; // first solution for (unsigned long int i = 0; i != 10000000; ++i) a = fun(start, 2)[3]; // second solution F f; for (unsigned long int i = 0; i != 10000000; ++i) { f(start, 2); a = f.output[3]; } } Yes, I can use inline or optimize in an other way this problem, but here I want to stress on this problem: with the functor I declare and construct the output variable output only one time, using the function I do that every time it is called. The second solution is two time faster than the first with g++ -O1 or g++ -O2. What do you think about it, is it an ugly optimization?

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