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• WPF User Control is causing Out of Memory Exception

  - by Chairman Meow

  Looking for a free spell checking solution, I thought I was so smart in doing this but I guess not. I have created a windows form based application and I want the form to add a user specified amount of user controls (with textboxes) on to a panel. The user can then click some button and the controls on this panel are cleared and new ones are added. The user does something and the process is repeated. Now, I wanted these textboxes to support spell checking and looked all over for a free solution. WPF textboxes support spell checking where the ones in regular win forms do not. I thought I would be able to use these WPF textboxes by adding them to an ElementHost object which is, in turn, within a panel. This panel would be a user control. So, in my application, I would be able to add instances of these user controls onto the form and make use of .NET's spell checking goodness. This actually worked but after using the application for a while, found that the application would eventually freeze on me due to out of memory errors. I have pinpointed the memory errors to these WPF controls since this problem does not happen with normal textboxes. When the window is opened and the number of controls is specified, this is pretty much how the controls are added: Dim xOffset As Integer = 0 For i As Integer = 0 To theNumber Dim myUserControl As New SpecialUserControl() myPanel.Controls.Add(myUserControl) myUserControl.Location = New Point(7, 7) myUserControl.Location = New Point(xOffset, 7) xOffset = xOffset + 207 Next Note that: myPanel is a panel on a form SpecialUserControl is the user control with WPF textbox (within an ElementHost object) When the user pressed a button, the panel is cleared: myUserControl.Controls.Clear() The user can then repeat the process. There are a lot of results on the internet when I tried to find a solution and I'm thinking that the problem I am having is due to the fact that the WPF control is not going away even after clearing the panel. Following this conclusion, I have tried different solutions regarding disposing these controls or setting them to nothing but the memory problem keeps occurring. If someone could give me some advice or ideas here, I'd really appreciate it.

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• Memory leak for NSDictionary loaded by plist file

  - by Pask

  I have a memory leak problem that just can not understand! Watch this initialization method: - (id)initWithNomeCompositore:(NSString *)nomeCompositore nomeOpera:(NSString *)nomeOpera { if (self = [super init]) { NSString *pathOpere = [[NSBundle mainBundle] pathForResource:kNomeFilePlistOpere ofType:kTipoFilePlist]; NSDictionary *dicOpera = [NSDictionary dictionaryWithDictionary: [[[NSDictionary dictionaryWithContentsOfFile:pathOpere] objectForKey:nomeCompositore] objectForKey:nomeOpera]]; self.nomeCompleto = [[NSString alloc] initWithString:nomeOpera]; self.compositore = [[NSString alloc] initWithString:nomeCompositore]; self.tipologia = [[NSString alloc] initWithString:[dicOpera objectForKey:kKeyTipologia]]; } return self;} Then this little variation (note self.tipologia): - (id)initWithNomeCompositore:(NSString *)nomeCompositore nomeOpera:(NSString *)nomeOpera { if (self = [super init]) { NSString *pathOpere = [[NSBundle mainBundle] pathForResource:kNomeFilePlistOpere ofType:kTipoFilePlist]; NSDictionary *dicOpera = [NSDictionary dictionaryWithDictionary: [[[NSDictionary dictionaryWithContentsOfFile:pathOpere] objectForKey:nomeCompositore] objectForKey:nomeOpera]]; self.nomeCompleto = [[NSString alloc] initWithString:nomeOpera]; self.compositore = [[NSString alloc] initWithString:nomeCompositore]; self.tipologia = [[NSString alloc] initWithString:@"Test"]; } return self;} In the first variant is generated a memory leak, the second is not! And I just can not understand why! The memory leak is evidenced by Instruments, highlighted the line: [NSDictionary dictionaryWithContentsOfFile:pathOpere] This is the dealloc method: - (void)dealloc { [tipologia release]; [compositore release]; [nomeCompleto release]; [super dealloc];}

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• WPF Spellcheck Engine takes up too much memory.

  - by Matt H.

  Each datatemplate in my WPF ItemsControl contains FIVE custom bindable richtextbox controls. It is a data-driven app that for authoring multiple-choice questions -- The question and four answer choices must all support: 1) Spell check 2) Rich formatting (otherwise I'd use regular textboxes) The spell check object in .NET 4 has a Friend constructor that takes a single argument of owner As TextBoxBase This means every richtextbox in the ItemsControl has 5 Spellcheck objects! This is the problem -- every spell check engine is consuming about 500k memory. So after you favor in the spellcheck, bindings, additional controls in the DataTemplate, etc.. a single multi choice question consumes more than 3MB memory. Users with 100--200 questions will quickly see the App raise it's memory consumption to 500+ MB. Management is definitely not OK with this. Is there a way to minimimze this problem? The best suggestion I've heard is to enable/disable spellcheck if the richtextbox is in the ItemsControl's scrollviewer: I haven't gotten an answer to how to go about it: (http://stackoverflow.com/questions/2869012/possible-to-implement-an-isviewportvisible-dependencyproperty-for-an-item-in-an-i) Any good ideas?

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• IPhone SDK - Leaking Memory with performSelectorInBackground

  - by Steblo

  Hi. Maybe someone can help me with this strange thing: If a user clicks on a button, a new UITableView is pushed to the navigation controller. This new view is doing some database querying which takes some time. Therefore I wanted to do the loading in background. What works WITHOUT leaking memory (but freezes the screen until everything is done): WorkController *tmp=[[WorkController alloc] initWithStyle:UITableViewStyleGrouped]; self.workController=tmp; [tmp release]; [self.workController loadList]; // Does the DB Query [self.workController pushViewController:self.workController animated:YES]; Now I tried to do this: // Show Wait indicator .... WorkController *tmp=[[WorkController alloc] initWithStyle:UITableViewStyleGrouped]; self.workController=tmp; [tmp release]; [self performSelectorInBackground:@selector(getController) withObject:nil]; } -(void) getController { [self.workController loadList]; // Does the DB Query [self.navigationController pushViewController:self.workController animated:YES]; } This also works but is leaking memory and I don't know why ! Can you help ? By the way - is it possible for an App to get into AppStore with a small memory leak ? Or will this be checked first of all ? Thanks in advance !

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• C#: Accessing PerformanceCounters for the ".NET CLR Memory category"

  - by Mads Ravn

  I'm trying to access the performance counters located in ".NET CLR Memory category" through C# using the PerformanceCounter class. However a cannot instantiate the categories with what I would expect was the correct category/counter name new PerformanceCounter(".NET CLR Memory", "# bytes in all heaps", Process.GetCurrentProcess().ProcessName); I tried looping through categories and counters using the following code string[] categories = PerformanceCounterCategory.GetCategories().Select(c => c.CategoryName).OrderBy(s => s).ToArray(); string toInspect = string.Join(",\r\n", categories); System.Text.StringBuilder interestingToInspect = new System.Text.StringBuilder(); string[] interestingCategories = categories.Where(s => s.StartsWith(".NET") || s.Contains("Memory")).ToArray(); foreach (string interestingCategory in interestingCategories) { PerformanceCounterCategory cat = new PerformanceCounterCategory(interestingCategory); foreach (PerformanceCounter counter in cat.GetCounters()) { interestingToInspect.AppendLine(interestingCategory + ":" + counter.CounterName); } } toInspect = interestingToInspect.ToString(); But could not find anything that seems to match. Is it not possible to observe these values from within the CLR or am I doing something wrong. The environment, should it matter, is .NET 4.0 running on a 64-bit windows 7 box.

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• Free Memory Occupied by Std List, Vector, Map etc

  - by Graviton

  Coming from a C# background, I have only vaguest idea on memory management on C++-- all I know is that I would have to free the memory manually. As a result my C++ code is written in such a way that objects of the type std::vector, std::list, std::map are freely instantiated, used, but not freed. I didn't realize this point until I am almost done with my programs, now my code is consisted of the following kinds of patterns: struct Point_2 { double x; double y; }; struct Point_3 { double x; double y; double z; }; list<list<Point_2>> Computation::ComputationJob(list<Point_3> pts3D, vector<Point_2> vectors) { map<Point_2, double> pt2DMap=ConstructPointMap(pts3D); vector<Point_2> vectorList = ConstructVectors(vectors); list<list<Point_2>> faceList2D=ConstructPoints(vectorList , pt2DMap); return faceList2D; } My question is, must I free every.single.one of the list usage ( in the above example, this means that I would have to free pt2DMap, vectorList and faceList2D)? That would be very tedious! I might just as well rewrite my Computation class so that it is less prone to memory leak. Any idea how to fix this?

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• Boost Unit testing memory reuse causing tests that should fail to pass

  - by Knyphe

  We have started using the boost unit testing library for a large existing code base, and I have run into some trouble with unit tests incorrectly passing, seemingly due to the reuse of memory on the stack. Here is my situation: BOOST_AUTO_TEST_CASE(test_select_base_instantiation_default) { SelectBase selectBase(); BOOST_CHECK_EQUAL( selectBase.getSelectType(), false); BOOST_CHECK_EQUAL( selectBase.getTypeName(_T("")); BOOST_CHECK_EQUAL( selectBase.getEntityType(), -1); BOOST_CHECK_EQUAL( selectBase.getDataPos(), -1); } BOOST_AUTO_TEST_CASE(test_select_base_instantiation_default) { SelectBase selectBase(true, _T("abc")); BOOST_CHECK_EQUAL( selectBase.getSelectType(), false); BOOST_CHECK_EQUAL( selectBase.getTypeName(_T("abc")); BOOST_CHECK_EQUAL( selectBase.getEntityType(), -1); BOOST_CHECK_EQUAL( selectBase.getDataPos(), -1); } The first test passed correctly, initializing all the variables. The constructor in the second unit test did not correctly set EntityType or DataPosition, but the unit test passed. I was able to get it to fail by placing some variables on the stack in the second test, like so: BOOST_AUTO_TEST_CASE(test_select_base_instantiation_default) { int a, b; SelectBase selectBase(true, _T("abc")); BOOST_CHECK_EQUAL( selectBase.getSelectType(), false); BOOST_CHECK_EQUAL( selectBase.getTypeName(_T("abc")); BOOST_CHECK_EQUAL( selectBase.getEntityType(), -1); BOOST_CHECK_EQUAL( selectBase.getDataPos(), -1); } If there is only one int, only the dataPos CHECK_EQUAL fails, but if there are two, both EntityType and DataPos fail, so it seems pretty clear that this is an issue with the variables being created on the same stack memory or some such. Is there a good way to clear the memory between each unit test, or am I potentially using the library incorrectly or writing bad tests? Any help would be appreciated.

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• Linux C debugging library to detect memory corruptions

  - by calandoa

  When working sometimes ago on an embedded system with a simple MMU, I used to program dynamically this MMU to detect memory corruptions. For instance, at some moment at runtime, the foo variable was overwritten with some unexpected data (probably by a dangling pointer or whatever). So I added the additional debugging code : at init, the memory used by foo was indicated as a forbidden region to the MMU; each time foo was accessed on purpose, access to the region was allowed just before then forbidden just after; a MMU irq handler was added to dump the master and the address responsible of the violation. This was actually some kind of watchpoint, but directly self-handled by the code itself. Now, I would like to reuse the same trick, but on a x86 platform. The problem is that I am very far from understanding how is working the MMU on this platform, and how it is used by Linux, but I wonder if any library/tool/system call already exist to deal with this problem. Note that I am aware that various tools exist like Valgrind or GDB to manage memory problems, but as far as I know, none of these tools car be dynamically reconfigured by the debugged code. I am mainly interested for user space under Linux, but any info on kernel mode or under Windows is also welcome!

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• Memory leaks while using array of double

  - by Gacek

  I have a part of code that operates on large arrays of double (containing about 6000 elements at least) and executes several hundred times (usually 800) . When I use standard loop, like that: double[] singleRow = new double[6000]; int maxI = 800; for(int i=0; i<maxI; i++) { singleRow = someObject.producesOutput(); //... // do something with singleRow // ... } The memory usage rises for about 40MB (from 40MB at the beggining of the loop, to the 80MB at the end). When I force to use the garbage collector to execute at every iteration, the memory usage stays at the level of 40MB (the rise is unsignificant). double[] singleRow = new double[6000]; int maxI = 800; for(int i=0; i<maxI; i++) { singleRow = someObject.producesOutput(); //... // do something with singleRow // ... GC.Collect() } But the execution time is 3 times longer! (it is crucial) How can I force the C# to use the same area of memory instead of allocating new ones? Note: I have the access to the code of someObject class, so if it would be needed, I can change it.

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• Usage of VIsual Memory Leak Detector

  - by Yan Cheng CHEOK

  I found a very interesting memory leak detector by using Visual C++. http://www.codeproject.com/KB/applications/visualleakdetector.aspx I try it out, but cannot make it works to detect a memory leak code. I am using MS Visual Studio 2008. Any step I had missed out? #include "stdafx.h" #include "vld.h" #include <iostream> void fun() { new int[1000]; } int _tmain(int argc, _TCHAR* argv[]) { fun(); std::cout << "lead?" << std::endl; getchar(); return 0; } The output when I run in debug mode is : ... ... 'Test.exe': Loaded 'C:\WINDOWS\WinSxS\x86_Microsoft.VC80.CRT_1fc8b3b9a1e18e3b_8.0.50727.4053_x-ww_e6967989\msvcr80.dll', Symbols loaded. 'Test.exe': Loaded 'C:\WINDOWS\system32\msvcrt.dll', Symbols loaded (source information stripped). 'Test.exe': Loaded 'C:\WINDOWS\WinSxS\x86_Microsoft.VC90.DebugCRT_1fc8b3b9a1e18e3b_9.0.30729.1_x-ww_f863c71f\msvcp90d.dll', Symbols loaded. 'Test.exe': Loaded 'C:\Program Files\Visual Leak Detector\bin\dbghelp.dll', Symbols loaded (source information stripped). Visual Leak Detector Version 1.9d installed. No memory leaks detected. Visual Leak Detector is now exiting. The program '[5468] Test.exe: Native' has exited with code 0 (0x0).

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• iPhone: Low memory crash...

  - by MacTouch

  Once again I'm hunting memory leaks and other crazy mistakes in my code. :) I have a cache with frequently used files (images, data records etc. with a TTL of about one week and a size limited cache (100MB)). There are sometimes more then 15000 files in a directory. On application exit the cache writes an control file with the current cache size along with other useful information. If the applications crashes for some reason (sh.. happens sometimes) I have in such case to calculate the size of all files on application start to make sure I know the cache size. My app crashes at this point because of low memory and I have no clue why. Memory leak detector does not show any leaks at all. I do not see any too. What's wrong with the code below? Is there any other fast way to calculate the total size of all files within a directory on iPhone? Maybe without to enumerate the whole contents of the directory? The code is executed on the main thread. NSUInteger result = 0; NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; NSDirectoryEnumerator *dirEnum = [[[NSFileManager defaultManager] enumeratorAtPath:path] retain]; int i = 0; while ([dirEnum nextObject]) { NSDictionary *attributes = [dirEnum fileAttributes]; NSNumber* fileSize = [attributes objectForKey:NSFileSize]; result += [fileSize unsignedIntValue]; if (++i % 500 == 0) { // I tried lower values too [pool drain]; } } [dirEnum release]; dirEnum = nil; [pool release]; pool = nil; Thanks, MacTouch

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• FileConnection Blackberry memory usage

  - by Dean

  Hello, I'm writing a blackberry application that reads ints and strings out of a database. This is my first time dealing with reading/writing on the blackberry, so forgive me if this is a dumb question. The database file I'm reading is only about 4kB I open the file with the following code fconn = (FileConnection) Connector.open("file_path_here", Connector.READ); if(fconn.exists()==false){fconn.close();return;} is = fconn.openDataInputStream(); while(!eof){ //etc... } is.close(); fconn.close(); The problem is, this code appears to be eating a LOT of memory. Using breakpoints and the "Memory Statistics" view, I determined the following: calling "Connector.open" creates 71 objects and changes "RAM Bytes in use" by 5376 calling "fconn.openDataInputStream();" increases RAM usage by a whopping 75920 Is this normal? Or am I doing something wrong? And how can I fix this? 75MB of RAM is a LOT of memory to waste on a handheld device, especially when the file I'm reading is only 4kB and I haven't even begun reading any data! How is this even possible?

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• Activator.CreateInstance uses a huge amount of memory

  - by Marco

  I have been playing a bit with Silverlight and try to port my Silverlight 3.0 application to Silverlight 4.0. My application loads different XAP files and upon a user request create an instance of a Xaml user control and adds it to the main container, in a sort of MEF approach in order I can have an extensible and pluggable application. The application is pretty huge and to keep acceptable the performances and the initial loading I have built up some helper classes to load in the background all pages and user controls that might be used later on. On Silverlight 3.0 everything was running smoothly without any problem so far. Switching to SL 4.0 I have noticed that when the process approaches to create the instances of the user controls using Activator.CreateInstance, the layout freezes unexpectedly for a minute and sometimes for more. Looking at the task manager the memory usage of IE jumps from 50MB to 400MB and sometimes to 1.5 GB. If the process won't take that much the layout is rendered properly and the memory falls back to 50 MB. Otherwise everything crashes due to out of memory exeption. Does anybody encountered the same problem? Or has anybody a solution about this tricky issue?

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• Proper Memory Management for Objective-C Method

  - by Justin

  Hi, I'm programming an iPhone app and I had a question about memory management in one of my methods. I'm still a little new to managing memory manually, so I'm sorry if this question seems elementary. Below is a method designed to allow a number pad to place buttons in a label based on their tag, this way I don't need to make a method for each button. The method works fine, I'm just wondering if I'm responsible for releasing any of the variables I make in the function. The application crashes if I try to release any of the variables, so I'm a little confused about my responsibility regarding memory. Here's the method: FYI the variable firstValue is my label, it's the only variable not declared in the method. -(IBAction)inputNumbersFromButtons:(id)sender { UIButton *placeHolderButton = [[UIButton alloc] init]; placeHolderButton = sender; NSString *placeHolderString = [[NSString alloc] init]; placeHolderString = [placeHolderString stringByAppendingString:firstValue.text]; NSString *addThisNumber = [[NSString alloc] init]; int i = placeHolderButton.tag; addThisNumber = [NSString stringWithFormat:@"%i", i]; NSString *newLabelText = [[NSString alloc] init]; newLabelText = [placeHolderString stringByAppendingString:addThisNumber]; [firstValue setText:newLabelText]; //[placeHolderButton release]; //[placeHolderString release]; //[addThisNumber release]; //[newLabelText release]; } The application works fine with those last four lines commented out, but it seems to me like I should be releasing these variables here. If I'm wrong about that I'd welcome a quick explanation about when it's necessary to release variables declared in functions and when it's not. Thanks.

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• Memory Management with returning char* function

  - by RageD

  Hello all, Today, without much thought, I wrote a simple function return to a char* based on a switch statement of given enum values. This, however, made me wonder how I could release that memory. What I did was something like this: char* func() { char* retval = new char; // Switch blah blah - will always return some value other than NULL since default: return retval; } I apologize if this is a naive question, but what is the best way to release the memory seeing as I cannot delete the memory after the return and, obviously, if I delete it before, I won't have a returned value. What I was thinking as a viable solution was something like this void func(char*& in) { // blah blah switch make it do something } int main() { char* val = new char; func(val); // Do whatever with func (normally func within a data structure with specific enum set so could run multiple times to change output) val = NULL; delete val; val = NULL; return 0; } Would anyone have anymore insight on this and/or explanation on which to use? Regards, Dennis M.

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• PHP memory exhausted when running through thousands of records

  - by James Skidmore

  I'm running the following code over a set of 5,000 results. It's failing due to the memory being exhausted. foreach ($data as $key => $report) { $data[$key]['data'] = unserialize($report['serialized_values']); } I know I can up the memory limit, but I'd like to run this without a problem instead. I'm not going to be able to keep upping the memory forever. EDIT The $data is in this format: [1] => Array ( [0] => 127654619178790249 [report_id] => 127654619178790249 [1] => 1 [user_id] => 1 [2] => 2010-12-31 19:43:24 [sent_on] => 2010-12-31 19:43:24 [3] => [fax_trans_id] => [4] => 1234567890 [fax_to_nums] => 1234567890 [5] => ' long html string here', [html_content] => 'long html string here', [6] => 'serialization_string_here', [serialized_values] => 'serialization_string_here', [7] => 70 [id] => 70 )

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• Does ReleaseStringUTF do more than free memory?

  - by Bayou Bob

  Consider the following C code segments. Segment 1: char * getSomeString(JNIEnv *env, jstring jstr) { char * retString; retString = (*env)->GetStringUTFChars(env, jstr, NULL); return retString; } void useSomeString(JNIEnv *env, jobject jobj, char *mName) { jclass cl = (*env)->GetObjectClass(env, jobj); jmethodId mId = (*env)->GetMethodID(env, cl, mName, "()Ljava/lang/String;"); jstring jstr = (*env)->CallObjectMethod(env, obj, id, NULL); char * myString = getSomeString(env, jstr); /* ... use myString without modifing it */ free(myString); } Because myString is freed in useSomeString, I do not think I am creating a memory leak; however, I am not sure. The JNI spec specifically requires the use of ReleaseStringUTFChars. Since I am getting a C style 'char *' pointer from GetStringUTFChars, I believe the memory reference exists on the C stack and not in the JAVA heap so it is not in danger of being Garbage Collected; however, I am not sure. I know that changing getSomeString as follows would be safer (and probably preferable). Segment 2: char * getSomeString(JNIEnv *env, jstring jstr) { char * retString; char * intermedString; intermedString = (*env)->GetStringUTFChars(env, jstr, NULL); retString = strdup(intermedString); (*env)->ReleaseStringUTFChars(env, jstr, intermedString); return retString; } Because of our 'process' I need to build an argument on why getSomeString in Segment 2 is preferable to Segment 1. Is anyone aware of any documentation or references which detail the behavior of GetStringUTFChars and ReleaseStringUTFChars in relation to where memory is allocated or what (if any) additional bookkeeping is done (i.e. local Reference Pointer to the Java Heap being created, etc). What are the specific consequences of ignoring that bookkeeping. Thanks in advance.

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• php memory how much is too much

  - by Rob

  I'm currently re-writing my site using my own framework (it's very simple and does exactly what I need, i've no need for something like Zend or Cake PHP). I've done alot of work in making sure everything is cached properly, caching pages in files so avoid sql queries and generally limiting the number of sql queries. Overall it looks like it's very speedy. The average time taken for the front page (taken over 100 times) is 0.046152 microseconds. But one thing i'm not sure about is whether i've done enough to reduce php memory usage. The only time i've ever encountered problems with it is when uploading large files. Using memory_get_peak_usage(TRUE), which I THINK returns the highest amount of memory used whilst the script has been running, the average (taken over 100 times) is 1572864 bytes. Is that good? I realise you don't know what it is i'm doing (it's rather simple, get the 10 latest articles, the comment count for each, get the user controls, popular tags in the sidebar etc). But would you be at all worried with a script using that sort of memory getting hit 50,000 times a day? Or once every second at peak times? I realise that this is a very open ended question. Hopefully you can understand that it's a bit of a stab in the dark and i'm really just looking for some re-assurance that it's not going to die horribly come re-launch day.

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• Error -12 hibernation image. Not enough free memory (sometimes)

  - by user99306

  I am having a problem with hibernation in Ubuntu 12.10, it had worked fine in 12.04. When I try and hibernate it sometimes appears to hibernate throws up an error and returns me to the desktop. The error I get is this: PM: Creating hibernation image: PM: Need to copy 375021 pages PM: Normal pages needed: 117957 + 1024, available pages: 110205 PM: Not enough free memory PM: Error -12 creating hibernation image Now I understand what the error means, but it doesn't make sense. My swap file is 5GB and is seldom ever used as I have 4GB of RAM. I know it is recommended to have 1.5 times more swap than RAM etc, but space doesn't seem to be the problem, despite the error. For example, I rarely use more than about 25%-30% of my RAM, yet still have the problem above. Moreover on a fresh boot and login, with no programs open and using only about 12% of RAM, I can get the above error - yet at other times I can hibernate whilst using 25% of my RAM. Also if I keep trying to hibernate, it eventually does after throwing up the above error four or five times. A successful hibernation looks like this: PM: Creating hibernation image: PM: Need to copy 295511 pages PM: Normal pages needed: 95534 + 1024, available pages: 132627 Is there some setting that I need to tweak or something I need to do before hibernating to avoid this problem? I guess the question could be better interpreted as: Is there some way of safely flushing the buffers and the cache before hibernation? Other than attempting to hibernate several times until it is successful! Thanks in advance.

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• Static vs. dynamic memory allocation - lots of constant objects, only small part of them used at runtime

  - by k29

  Here are two options: Option 1: enum QuizCategory { CATEGORY_1(new MyCollection<Question>() .add(Question.QUESTION_A) .add(Question.QUESTION_B) .add...), CATEGORY_2(new MyCollection<Question>() .add(Question.QUESTION_B) .add(Question.QUESTION_C) .add...), ... ; public MyCollection<Question> collection; private QuizCategory(MyCollection<Question> collection) { this.collection = collection; } public Question getRandom() { return collection.getRandomQuestion(); } } Option 2: enum QuizCategory2 { CATEGORY_1 { @Override protected MyCollection<Question> populateWithQuestions() { return new MyCollection<Question>() .add(Question.QUESTION_A) .add(Question.QUESTION_B) .add...; } }, CATEGORY_2 { @Override protected MyCollection<Question> populateWithQuestions() { return new MyCollection<Question>() .add(Question.QUESTION_B) .add(Question.QUESTION_C) .add...; } }; public Question getRandom() { MyCollection<Question> collection = populateWithQuestions(); return collection.getRandomQuestion(); } protected abstract MyCollection<Question> populateWithQuestions(); } There will be around 1000 categories, each containing 10 - 300 questions (100 on average). At runtime typically only 10 categories and 30 questions will be used. Each question is itself an enum constant (with its fields and methods). I'm trying to decide between those two options in the mobile application context. I haven't done any measurements since I have yet to write the questions and would like to gather more information before committing to one or another option. As far as I understand: (a) Option 1 will perform better since there will be no need to populate the collection and then garbage-collect the questions; (b) Option 1 will require extra memory: 1000 categories x 100 questions x 4 bytes for each reference = 400 Kb, which is not significant. So I'm leaning to Option 1, but just wondered if I'm correct in my assumptions and not missing something important? Perhaps someone has faced a similar dilemma? Or perhaps it doesn't actually matter that much?

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• Shadow volume shader optimization (GLSL)

  - by Soubok

  I wondering if there is a way to optimize this vertex shader. This vertex shader projects (in the light direction) a vertex to the far plane if it is in the shadow. void main(void) { vec3 lightDir = (gl_ModelViewMatrix * gl_Vertex - gl_LightSource[0].position).xyz; // if the vertex is lit if ( dot(lightDir, gl_NormalMatrix * gl_Normal) < 0.01 ) { // don't move it gl_Position = ftransform(); } else { // move it far, is the light direction vec4 fin = gl_ProjectionMatrix * ( gl_ModelViewMatrix * gl_Vertex + vec4(normalize(lightDir) * 100000.0, 0.0) ); if ( fin.z > fin.w ) // if fin is behind the far plane fin.z = fin.w; // move to the far plane (needed for z-fail algo.) gl_Position = fin; } }

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• MySql query optimization help

  - by rohitgu

  I have few queries and am not able to figure out how to optimize them, QUERY 1 select * from t_twitter_tracking where classified is null and tweetType='ENGLISH' order by id limit 500; QUERY 2 Select count(*) as cnt, DATE_FORMAT(CONVERT_TZ(wrdTrk.createdOnGMTDate,'+00:00','+05:30'),'%Y-%m-%d') as dat from t_twitter_tracking wrdTrk where wrdTrk.word like ('dell') and CONVERT_TZ(wrdTrk.createdOnGMTDate,'+00:00','+05:30') between '2010-12-12 00:00:00' and '2010-12-26 00:00:00' group by dat; Both these queries run on the same table, CREATE TABLE `t_twitter_tracking` ( `id` BIGINT(20) NOT NULL AUTO_INCREMENT, `word` VARCHAR(200) NOT NULL, `tweetId` BIGINT(100) NOT NULL, `twtText` VARCHAR(800) NULL DEFAULT NULL, `language` TEXT NULL, `links` TEXT NULL, `tweetType` VARCHAR(20) NULL DEFAULT NULL, `source` TEXT NULL, `sourceStripped` TEXT NULL, `isTruncated` VARCHAR(40) NULL DEFAULT NULL, `inReplyToStatusId` BIGINT(30) NULL DEFAULT NULL, `inReplyToUserId` INT(11) NULL DEFAULT NULL, `rtUsrProfilePicUrl` TEXT NULL, `isFavorited` VARCHAR(40) NULL DEFAULT NULL, `inReplyToScreenName` VARCHAR(40) NULL DEFAULT NULL, `latitude` BIGINT(100) NOT NULL, `longitude` BIGINT(100) NOT NULL, `retweetedStatus` VARCHAR(40) NULL DEFAULT NULL, `statusInReplyToStatusId` BIGINT(100) NOT NULL, `statusInReplyToUserId` BIGINT(100) NOT NULL, `statusFavorited` VARCHAR(40) NULL DEFAULT NULL, `statusInReplyToScreenName` TEXT NULL, `screenName` TEXT NULL, `profilePicUrl` TEXT NULL, `twitterId` BIGINT(100) NOT NULL, `name` TEXT NULL, `location` VARCHAR(100) NULL DEFAULT NULL, `bio` TEXT NULL, `url` TEXT NULL COLLATE 'latin1_swedish_ci', `utcOffset` INT(11) NULL DEFAULT NULL, `timeZone` VARCHAR(100) NULL DEFAULT NULL, `frenCnt` BIGINT(20) NULL DEFAULT '0', `createdAt` DATETIME NULL DEFAULT NULL, `createdOnGMT` VARCHAR(40) NULL DEFAULT NULL, `createdOnServerTime` DATETIME NULL DEFAULT NULL, `follCnt` BIGINT(20) NULL DEFAULT '0', `favCnt` BIGINT(20) NULL DEFAULT '0', `totStatusCnt` BIGINT(20) NULL DEFAULT NULL, `usrCrtDate` VARCHAR(200) NULL DEFAULT NULL, `humanSentiment` VARCHAR(30) NULL DEFAULT NULL, `replied` BIT(1) NULL DEFAULT NULL, `replyMsg` TEXT NULL, `classified` INT(32) NULL DEFAULT NULL, `createdOnGMTDate` DATETIME NULL DEFAULT NULL, `locationDetail` TEXT NULL, `geonameid` INT(11) NULL DEFAULT NULL, `country` VARCHAR(255) NULL DEFAULT NULL, `continent` CHAR(2) NULL DEFAULT NULL, `placeLongitude` FLOAT NULL DEFAULT NULL, `placeLatitude` FLOAT NULL DEFAULT NULL, PRIMARY KEY (`id`), INDEX `id` (`id`, `word`), INDEX `createdOnGMT_index` (`createdOnGMT`) USING BTREE, INDEX `word_index` (`word`) USING BTREE, INDEX `location_index` (`location`) USING BTREE, INDEX `classified_index` (`classified`) USING BTREE, INDEX `tweetType_index` (`tweetType`) USING BTREE, INDEX `getunclassified_index` (`classified`, `tweetType`) USING BTREE, INDEX `timeline_index` (`word`, `createdOnGMTDate`, `classified`) USING BTREE, INDEX `createdOnGMTDate_index` (`createdOnGMTDate`) USING BTREE, INDEX `locdetail_index` (`country`, `id`) USING BTREE, FULLTEXT INDEX `twtText_index` (`twtText`) ) COLLATE='utf8_general_ci' ENGINE=MyISAM ROW_FORMAT=DEFAULT AUTO_INCREMENT=12608048; The table has more than 10 million records. How can I optimize it?

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• Mysql Sub Select Query Optimization

  - by Matt

  I'm running a query daily to compile stats - but it seems really inefficient. This is the Query: SELECT a.id, tstamp, label_id, (SELECT author_id FROM b WHERE b.tid = a.id ORDER BY b.tstamp DESC LIMIT 1) AS author_id FROM a, b WHERE (status = '2' OR status = '3') AND category != 6 AND a.id = b.tid AND (b.type = 'C' OR b.type = 'R') AND a.tstamp1 BETWEEN {$timestamp_start} AND {$timestamp_end} ORDER BY b.tstamp DESC LIMIT 500 This query seems to run really slow. Apologies for the crap naming - I've been asked to not reveal the actual table names. The reason there is a sub select is because the outer select gets one row from the table a and it gets a row from table b. But also need to know the latest author_id from table b as well, so I run a subselect to return that one. I don't want to run another select inside a php loop - as that is also inefficient. It works correctly - I just need to find a much faster way of getting this data set.

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• Java code optimization on matrix windowing computes in more time

  - by rano

  I have a matrix which represents an image and I need to cycle over each pixel and for each one of those I have to compute the sum of all its neighbors, ie the pixels that belong to a window of radius rad centered on the pixel. I came up with three alternatives: The simplest way, the one that recomputes the window for each pixel The more optimized way that uses a queue to store the sums of the window columns and cycling through the columns of the matrix updates this queue by adding a new element and removing the oldes The even more optimized way that does not need to recompute the queue for each row but incrementally adjusts a previously saved one I implemented them in c++ using a queue for the second method and a combination of deques for the third (I need to iterate through their elements without destructing them) and scored their times to see if there was an actual improvement. it appears that the third method is indeed faster. Then I tried to port the code to Java (and I must admit that I'm not very comfortable with it). I used ArrayDeque for the second method and LinkedLists for the third resulting in the third being inefficient in time. Here is the simplest method in C++ (I'm not posting the java version since it is almost identical): void normalWindowing(int mat[][MAX], int cols, int rows, int rad){ int i, j; int h = 0; for (i = 0; i < rows; ++i) { for (j = 0; j < cols; j++) { h = 0; for (int ry =- rad; ry <= rad; ry++) { int y = i + ry; if (y >= 0 && y < rows) { for (int rx =- rad; rx <= rad; rx++) { int x = j + rx; if (x >= 0 && x < cols) { h += mat[y][x]; } } } } } } } Here is the second method (the one optimized through columns) in C++: void opt1Windowing(int mat[][MAX], int cols, int rows, int rad){ int i, j, h, y, col; queue<int>* q = NULL; for (i = 0; i < rows; ++i) { if (q != NULL) delete(q); q = new queue<int>(); h = 0; for (int rx = 0; rx <= rad; rx++) { if (rx < cols) { int mem = 0; for (int ry =- rad; ry <= rad; ry++) { y = i + ry; if (y >= 0 && y < rows) { mem += mat[y][rx]; } } q->push(mem); h += mem; } } for (j = 1; j < cols; j++) { col = j + rad; if (j - rad > 0) { h -= q->front(); q->pop(); } if (j + rad < cols) { int mem = 0; for (int ry =- rad; ry <= rad; ry++) { y = i + ry; if (y >= 0 && y < rows) { mem += mat[y][col]; } } q->push(mem); h += mem; } } } } And here is the Java version: public static void opt1Windowing(int [][] mat, int rad){ int i, j = 0, h, y, col; int cols = mat[0].length; int rows = mat.length; ArrayDeque<Integer> q = null; for (i = 0; i < rows; ++i) { q = new ArrayDeque<Integer>(); h = 0; for (int rx = 0; rx <= rad; rx++) { if (rx < cols) { int mem = 0; for (int ry =- rad; ry <= rad; ry++) { y = i + ry; if (y >= 0 && y < rows) { mem += mat[y][rx]; } } q.addLast(mem); h += mem; } } j = 0; for (j = 1; j < cols; j++) { col = j + rad; if (j - rad > 0) { h -= q.peekFirst(); q.pop(); } if (j + rad < cols) { int mem = 0; for (int ry =- rad; ry <= rad; ry++) { y = i + ry; if (y >= 0 && y < rows) { mem += mat[y][col]; } } q.addLast(mem); h += mem; } } } } I recognize this post will be a wall of text. Here is the third method in C++: void opt2Windowing(int mat[][MAX], int cols, int rows, int rad){ int i = 0; int j = 0; int h = 0; int hh = 0; deque< deque<int> *> * M = new deque< deque<int> *>(); for (int ry = 0; ry <= rad; ry++) { if (ry < rows) { deque<int> * q = new deque<int>(); M->push_back(q); for (int rx = 0; rx <= rad; rx++) { if (rx < cols) { int val = mat[ry][rx]; q->push_back(val); h += val; } } } } deque<int> * C = new deque<int>(M->front()->size()); deque<int> * Q = new deque<int>(M->front()->size()); deque<int> * R = new deque<int>(M->size()); deque< deque<int> *>::iterator mit; deque< deque<int> *>::iterator mstart = M->begin(); deque< deque<int> *>::iterator mend = M->end(); deque<int>::iterator rit; deque<int>::iterator rstart = R->begin(); deque<int>::iterator rend = R->end(); deque<int>::iterator cit; deque<int>::iterator cstart = C->begin(); deque<int>::iterator cend = C->end(); for (mit = mstart, rit = rstart; mit != mend, rit != rend; ++mit, ++rit) { deque<int>::iterator pit; deque<int>::iterator pstart = (* mit)->begin(); deque<int>::iterator pend = (* mit)->end(); for(cit = cstart, pit = pstart; cit != cend && pit != pend; ++cit, ++pit) { (* cit) += (* pit); (* rit) += (* pit); } } for (i = 0; i < rows; ++i) { j = 0; if (i - rad > 0) { deque<int>::iterator cit; deque<int>::iterator cstart = C->begin(); deque<int>::iterator cend = C->end(); deque<int>::iterator pit; deque<int>::iterator pstart = (M->front())->begin(); deque<int>::iterator pend = (M->front())->end(); for(cit = cstart, pit = pstart; cit != cend; ++cit, ++pit) { (* cit) -= (* pit); } deque<int> * k = M->front(); M->pop_front(); delete k; h -= R->front(); R->pop_front(); } int row = i + rad; if (row < rows && i > 0) { deque<int> * newQ = new deque<int>(); M->push_back(newQ); deque<int>::iterator cit; deque<int>::iterator cstart = C->begin(); deque<int>::iterator cend = C->end(); int rx; int tot = 0; for (rx = 0, cit = cstart; rx <= rad; rx++, ++cit) { if (rx < cols) { int val = mat[row][rx]; newQ->push_back(val); (* cit) += val; tot += val; } } R->push_back(tot); h += tot; } hh = h; copy(C->begin(), C->end(), Q->begin()); for (j = 1; j < cols; j++) { int col = j + rad; if (j - rad > 0) { hh -= Q->front(); Q->pop_front(); } if (j + rad < cols) { int val = 0; for (int ry =- rad; ry <= rad; ry++) { int y = i + ry; if (y >= 0 && y < rows) { val += mat[y][col]; } } hh += val; Q->push_back(val); } } } } And finally its Java version: public static void opt2Windowing(int [][] mat, int rad){ int cols = mat[0].length; int rows = mat.length; int i = 0; int j = 0; int h = 0; int hh = 0; LinkedList<LinkedList<Integer>> M = new LinkedList<LinkedList<Integer>>(); for (int ry = 0; ry <= rad; ry++) { if (ry < rows) { LinkedList<Integer> q = new LinkedList<Integer>(); M.addLast(q); for (int rx = 0; rx <= rad; rx++) { if (rx < cols) { int val = mat[ry][rx]; q.addLast(val); h += val; } } } } int firstSize = M.getFirst().size(); int mSize = M.size(); LinkedList<Integer> C = new LinkedList<Integer>(); LinkedList<Integer> Q = null; LinkedList<Integer> R = new LinkedList<Integer>(); for (int k = 0; k < firstSize; k++) { C.add(0); } for (int k = 0; k < mSize; k++) { R.add(0); } ListIterator<LinkedList<Integer>> mit; ListIterator<Integer> rit; ListIterator<Integer> cit; ListIterator<Integer> pit; for (mit = M.listIterator(), rit = R.listIterator(); mit.hasNext();) { Integer r = rit.next(); int rsum = 0; for (cit = C.listIterator(), pit = (mit.next()).listIterator(); cit.hasNext();) { Integer c = cit.next(); Integer p = pit.next(); rsum += p; cit.set(c + p); } rit.set(r + rsum); } for (i = 0; i < rows; ++i) { j = 0; if (i - rad > 0) { for(cit = C.listIterator(), pit = M.getFirst().listIterator(); cit.hasNext();) { Integer c = cit.next(); Integer p = pit.next(); cit.set(c - p); } M.removeFirst(); h -= R.getFirst(); R.removeFirst(); } int row = i + rad; if (row < rows && i > 0) { LinkedList<Integer> newQ = new LinkedList<Integer>(); M.addLast(newQ); int rx; int tot = 0; for (rx = 0, cit = C.listIterator(); rx <= rad; rx++) { if (rx < cols) { Integer c = cit.next(); int val = mat[row][rx]; newQ.addLast(val); cit.set(c + val); tot += val; } } R.addLast(tot); h += tot; } hh = h; Q = new LinkedList<Integer>(); Q.addAll(C); for (j = 1; j < cols; j++) { int col = j + rad; if (j - rad > 0) { hh -= Q.getFirst(); Q.pop(); } if (j + rad < cols) { int val = 0; for (int ry =- rad; ry <= rad; ry++) { int y = i + ry; if (y >= 0 && y < rows) { val += mat[y][col]; } } hh += val; Q.addLast(val); } } } } I guess that most is due to the poor choice of the LinkedList in Java and to the lack of an efficient (not shallow) copy method between two LinkedList. How can I improve the third Java method? Am I doing some conceptual error? As always, any criticisms is welcome. UPDATE Even if it does not solve the issue, using ArrayLists, as being suggested, instead of LinkedList improves the third method. The second one performs still better (but when the number of rows and columns of the matrix is lower than 300 and the window radius is small the first unoptimized method is the fastest in Java)

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• Matlab: Optimization by perturbing variable

  - by S_H

  My main script contains following code: %# Grid and model parameters nModel=50; nModel_want=1; nI_grid1=5; Nth=1; nRow.Scale1=5; nCol.Scale1=5; nRow.Scale2=5^2; nCol.Scale2=5^2; theta = 90; % degrees a_minor = 2; % range along minor direction a_major = 5; % range along major direction sill = var(reshape(Deff_matrix_NthModel,nCell.Scale1,1)); % variance of the coarse data matrix of size nRow.Scale1 X nCol.Scale1 %# Covariance computation % Scale 1 for ihRow = 1:nRow.Scale1 for ihCol = 1:nCol.Scale1 [cov.Scale1(ihRow,ihCol),heff.Scale1(ihRow,ihCol)] = general_CovModel(theta, ihCol, ihRow, a_minor, a_major, sill, 'Exp'); end end % Scale 2 for ihRow = 1:nRow.Scale2 for ihCol = 1:nCol.Scale2 [cov.Scale2(ihRow,ihCol),heff.Scale2(ihRow,ihCol)] = general_CovModel(theta, ihCol/(nCol.Scale2/nCol.Scale1), ihRow/(nRow.Scale2/nRow.Scale1), a_minor, a_major, sill/(nRow.Scale2*nCol.Scale2), 'Exp'); end end %# Scale-up of fine scale values by averaging [covAvg.Scale2,var_covAvg.Scale2,varNorm_covAvg.Scale2] = general_AverageProperty(nRow.Scale2/nRow.Scale1,nCol.Scale2/nCol.Scale1,1,nRow.Scale1,nCol.Scale1,1,cov.Scale2,1); I am using two functions, general_CovModel() and general_AverageProperty(), in my main script which are given as following: function [cov,h_eff] = general_CovModel(theta, hx, hy, a_minor, a_major, sill, mod_type) % mod_type should be in strings angle_rad = theta*(pi/180); % theta in degrees, angle_rad in radians R_theta = [sin(angle_rad) cos(angle_rad); -cos(angle_rad) sin(angle_rad)]; h = [hx; hy]; lambda = a_minor/a_major; D_lambda = [lambda 0; 0 1]; h_2prime = D_lambda*R_theta*h; h_eff = sqrt((h_2prime(1)^2)+(h_2prime(2)^2)); if strcmp(mod_type,'Sph')==1 || strcmp(mod_type,'sph') ==1 if h_eff<=a cov = sill - sill.*(1.5*(h_eff/a_minor)-0.5*((h_eff/a_minor)^3)); else cov = sill; end elseif strcmp(mod_type,'Exp')==1 || strcmp(mod_type,'exp') ==1 cov = sill-(sill.*(1-exp(-(3*h_eff)/a_minor))); elseif strcmp(mod_type,'Gauss')==1 || strcmp(mod_type,'gauss') ==1 cov = sill-(sill.*(1-exp(-((3*h_eff)^2/(a_minor^2))))); end and function [PropertyAvg,variance_PropertyAvg,NormVariance_PropertyAvg]=... general_AverageProperty(blocksize_row,blocksize_col,blocksize_t,... nUpscaledRow,nUpscaledCol,nUpscaledT,PropertyArray,omega) % This function computes average of a property and variance of that averaged % property using power averaging PropertyAvg=zeros(nUpscaledRow,nUpscaledCol,nUpscaledT); %# Average of property for k=1:nUpscaledT, for j=1:nUpscaledCol, for i=1:nUpscaledRow, sum=0; for a=1:blocksize_row, for b=1:blocksize_col, for c=1:blocksize_t, sum=sum+(PropertyArray((i-1)*blocksize_row+a,(j-1)*blocksize_col+b,(k-1)*blocksize_t+c).^omega); % add all the property values in 'blocksize_x','blocksize_y','blocksize_t' to one variable end end end PropertyAvg(i,j,k)=(sum/(blocksize_row*blocksize_col*blocksize_t)).^(1/omega); % take average of the summed property end end end %# Variance of averageed property variance_PropertyAvg=var(reshape(PropertyAvg,... nUpscaledRow*nUpscaledCol*nUpscaledT,1),1,1); %# Normalized variance of averageed property NormVariance_PropertyAvg=variance_PropertyAvg./(var(reshape(... PropertyArray,numel(PropertyArray),1),1,1)); Question: Using Matlab, I would like to optimize covAvg.Scale2 such that it matches closely with cov.Scale1 by perturbing/varying any (or all) of the following variables 1) a_minor 2) a_major 3) theta Thanks.

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